Heat-shock proteins: immunity and autoimmunity Douglas B. Young MRC Tuberculosis and Related Infections Unit, London, UK Antigens from a wide variety of pathogens have been identified as members of conserved heat-shock protein families, sharing upwards of 50% amino acid identity with corresponding host-cell proteins. Analysis of the responses to these conserved antigens may provide insights into regulation of the immune system during infection and autoimmunity. Current Opinion in Immunology 1992, 4:396-400 Introduction The heat-shock proteins (hsp) achieved immunological prominence on the basis of their identification as antigens in a wide range of pathogens and the recognition of the mycobacterial 65 kD hsp by arthritogenic T-cell clones in a rat adjuvant arthritis model (reviewed in [1,2] ). Extensive sequence conservation between microbial and mammalian hsp, coupled with variations in their, expression and subcellular location in response to environmental stress stimuli, fueled expectations that study of the immune response to hsp would contribute to an understanding of fundamental aspects of infection and autoimmunity. How far have these expectations been realized? The most prominent feature of the literature on hsp and immunity published over the last year is the preponderance of review articles in several periodicals, with
Seminars in Immunology 3, Current Topics in Microbiology and Immunology 167 and Immunological Reviews 121 providing entire issues on this topic. The present review focuses on recent primary publications, but the wide range of excellent in-depth reviews have provided a comprehensive analysis of the subject.
Hsp and the immune response to infection A large amount of work on the design of novel diagnostic probes and 'subunit' vaccines for infectious diseases has involved the identification of the individual components of pathogens that trigger immune responses. With a vast array of potential antigens from a protozoan parasite or pathogenic bacterium, it is attractive to speculate that the immune system might follow some discemable pattern in selecting particular targets for recognition. However, review of recent studies on individual pathogens does not provide much support for this proposal; for example, the list of antigens identified from blood-stage malaria parasites or mycobacterial pathogens seems bewildering in extent and diversity. Nevertheless, an overview of a vari-
ety of diseases has emphasized the antigenicity of members of conserved hsp families [1]. The identification of hsp as 'generic antigens' has prompted the suggestion that a study of their immune recognition may provide a useful comparison between different diseases. Differences in the immune response to hsp, in terms of the recognition of different epitopes or the involvement of functionally distinct lymphocyte subsets, might indicate differences in the way that particular pathogens interact with the immune system and may be useful in diagnosis. Similarities might suggest immune mechanisms common to different infections. Several studies over the last year have involved further characterization of the immune responses to bacterial hsp. The bacterial m e m b e r of the 60 kD hsp family, often referred to as GroEL, has been implicated in harmful T-cell responses during chlamydial infection [3]. Initial studies involved characterization of the antigen from Chlam3* alia psittaci and two further studies extended this to sequencing of groEL genes from the human pathogens C trachomatis and C. pneumonia [4,5]. By analogy with chlamydia, it is possible that immune responses to hsp60 may also play a role in the pathogenicity of Borrelia burgdorferi, the spirochete responsible for Lyme arthritis. A limited immunological characterization demonstrated the presence of antibodies in sera from Lyme disease patients and a T-cell clone identified a speciesspecific determinant on the B. burgdorferi GroEL [6*]. Burns et al. [7"] purified GroEL from Bordetellapertussis and found that standard diptheria-pertussis-tetanus vaccination induced an antibody response to hsp60 which included an element of crossreactivity to the mammalian homologue. Vaccination with purified GroEL provided only slight protection against a challenge with B. pertussis in animal models, and the authors speculate that its inclusion in vaccine preparations may be more likely to contribute to harmful side effects than to protective immunity [7~ Studies of GroEL from Legionella sp. [8] and from Pseudomonas aeruginosa [9] focused on the identification of genus-specific and species-specific epitopes recognized by monoclonal antibodies, while an
Abbreviations hsp~heat-shock protein; NOD--non-obese diabetic; PPD~purified protein derivative. 396
(g) Current Biology Ltd ISSN 0952-7915
Heat-shock proteins:immunityand autoimmunityYoung 397 extensive synthetic peptide analysis was used to examine genetic effects on the antibody responses to Mycobacterium leprae GroEL in mice [10]. An unexpected aspect of the bacterial GroEL studies was the finding of a second GroEL protein in some organisms. This was reported initially in Streptomyces [11] but has also been found in M. tuberculosis [ARM Coates, personal communication] and in M. leprae [12..]. GroEL is a molecular chaperone involved in folding, assembly and intracellular transport of proteins and has a functional interaction with a 10 kD hsp called GroES. An analysis of proliferative T-cell responses in leprosy patients led to the identification of M. leprae GroES as a major antigen, which was recognized by as many as one in three of the M. leprae-reactive T cells in peripheral blood of some patients [13o.]. In contrast to GroEL [10], attempts to map antibody responses to the mycobacterial GroES, using synthetic peptides, were rather unsuccessful [14]. Escherichia coli GroES is also much less effective than GroEL in the induction of antibodies (A Mehlert and DB Young, unpublished data), suggesting that there may be some qualitative difference in the immunogenicity of the two classes of protein. It is not yet known whether 'GroES' in eukaryotic cells is structurally as well as func tionally homologous with bacterial GroES [15] and the possibility of autoreactive responses to GroES has not been assessed. It will certainly be interesting, however, to look for T-cell responses to GroES in association with other bacterial infections. Another major antigenic hsp with a chaperone function is DnaK, the bacterial member of the hsp70 family. DnaK from M. leprae has been studied in detail over the past year by molecular and immunological analysis [16,17]. Previous findings of antibody and T-cell reactivity in leprosy patients were confirmed using recombinant antigen, with antibody responses being preferentially directed towards the variable carboxyl-terminal region of the protein [17]. Antibody responses to the corresponding recombinant M. tuberculosisDnaK were also analyzed using sera from tuberculosis patients [18]. Anti-DnaK antibodies were detected even in patients with a low bacterial load, suggesting that these may have some diagnostic use, in spite of a high level of autoantibodies detected using recombinant human hsp70 as antigen [18]. In contrast to GroEL, immune responses to chlamydial DnaK are associated with protection against disease. A synthetic peptide-mapping approach was used to localize two epitopes from chlamydial DnaK exposed on the surface of elementary bodies and recognized by neutralizing antibodies [19]. One of the epitopes was mapped in a conserved region of the protein (seven out of 10 residues identical to human hsp70) and future work may determine whether or not the protective antibodies also recognize corresponding regions from other hsp70 proteins. Finally, an intriguing study of antibody responses during systemic candidosis implicated hsp90 of Candida albicans as an important immune target capable of eliciting protective antibodies. Peptide mapping in this case again demonstrated that a neutralizing monoclonal antibody, as
well as patient antisera, recognized a highly conserved autoreactive, determinant of the protein [20~ The mechanism of the protective effect of these antibodies remains to be elucidated.
Hsp and animal models of autoimmunity The importance of hsp in animal models of autoimmunity was first recognized by the observation that autoreactive T-cell clones capable of transferring pathogenic symptoms of adjuvant arthritis in the rat model were directed to mycobacterial GroEL, the '65kD antigen'. Subsequently, it was found that vaccination with the purified mycobacterial antigen prevented the development of arthritis in rodent models following challenge not only with mycobacteria, but also with streptococcal cell walls, collagen or pristane. Interest focused on one particular epitope on the protein, amino acid residues 180-188, that was recognized by both protective and arthritogenic T cells and that could itself induce protection against adjuvant arthritis when administered as a synthetic peptide vaccine. This epitope was not conserved in the corresponding rodent hsp60 protein, and the mechanism of the protective effect was unclear (reviewed in [2] ). Several studies over the past year have lent further support to the proposed importance of the 65 kD antigen in adjuvant athritis. Hogervorst et aL [21 ~ demonstrated that T-cell proliferation in response to the 180-188 peptide was correlated with susceptibility to disease. T cells from resistant (Fischer) rats immunized with M. tuberculosis failed to proliferate to peptide 180-188, while the positive response by susceptible (Lewis) rats was inhibited by prior vaccination with the purified antigen, or peptide [21.]. The authors speculate that this may represent a difference in T-cell receptor repertoire between the two strains [21.]. Presentation of the 65kD antigen by vaccinia virus resembled vaccination with the purified antigen in generating a protective, rather than pathological, response [22]. Immune responses to the 65 kD antigen have also been implicated in regulation of the development of insulindependent diabetes in the non-obese diabetic (NOD) strain of mice [2]. Elias et al. [23**] went on to demonstrate that here, too, a single peptide determinant was recognized by diabetogenic clones and could confer protection in vaccination experiments. In this case the epitope (residues 437-460) was identical in all but one of its amino acids between bacterial and mammalian hsp60, suggesting that a model of 'antigenic mimicry' between corresponding hsp could account for the observations.
Hsp and human autoimmune disease Results from animal models prompted many investigators to look for an association with immune responses to hsp in human autoimmune diseases (reviewed in [1,2]). In
398
Immunityto infection particular, several reports described an enhanced proliferative response to the mycobacterial 65 kD antigen in experiments using T cells from synovial fluid of patients with rheumatoid or reactive arthritis and, in a similar vein, anti-hsp60 autoreactive T-cell responses were demonstrated (although their association with autoimmune disease was not established). Several publications over the last year have extended our knowledge in this area. The original conclusion that T-cell responses to mycobacterial 65 kD are elevated in rheumatoid synovia has been questioned in two ways. First, it has been suggested that this is not specific for the hsp and that, in fact, the same phenomenon can be demonstrated for other my cobacterial antigens [24]. Second, a careful study ofT-cell precursor frequency, comparing T cells from synovia and from peripheral blood, but using the same population of antigen-presenting cells in each case, led to the conclusion that the elevated response reported for synovial cells can be attributed to differences in antigen-presenting cell populations in the two compartments rather than to an altered distribution of T cells [25"]. This report deserves a special commendation in providing quantitative data on the 'immunodominance' of the mycobacterial 65 kD antigen. Most analyses of 65 kD responses in humans have been based on T-call clones or lines and, as a criterion for immunodominance, have relied on the oft-quoted result of mouse experiments showing that 65 kD reactivity accounts for one in five of all mycobacteria-reactive T cells [26]. Excluding one very low responder among the 10 patients in the present study, the frequency of 65kD-reactive T cells ranged from 1/2490 to 1/9600, with a mean of around 1/5 000 [25"]. By comparison, purified protein derivative (PPD)-reactivity in the same patients ranged from 1/300 to 1/8 030, with a mean of approximately 1/2 000. If PPD is considered to comprise a cross-section of mycobacterial antigens, these results suggest that the relative ratio of 65 kD-reactive to mycobacteria-reactive T cells is, in fact, broadly similar between mouse and man. The overall frequency of 65 kDreactive cells is within the range previously reported for tetanus toxoid (1/750 to 1/11 500), and is clearly lower than that of alloantigen-reactivity (1/200 to 1/600) [27]. No significant difference was found between control and rheumatoid arthritis patients [25"]; it would be interesting to see whether the numbers go up or down, during mycobacterial infection. Meanwhile, several other studies addressed the question of autoreactive hsp60 responses by synovial T cells. An autoreactive clone, capable of recognizing heat-stressed presenting cells in the absence of exogenous antigen, was isolated from a patient with Yersinia-related reactive arthritis [28.], but the bulk of the antimycobacterial response in rheumatoid synovia was found to be specific for the bacterial rather than the human hsp [29]. In contrast, strong responses to human hsp60 were found in synovial T cells from patients with juvenile chronic arthritis [30"~ suggesting a possible correlation with hsp autoreactivity in some forms of the disease. Responses to other, non-hsp, mycobacterial antigens have also been reported in such patients [31].
Hsp60 was initially identified in the mitochondria of mammalian cells, but it has recently been demonstrated that a cytoplasmic protein, referred to as 'TCP-I' in the mouse system, also belongs to the same chaperone family as GroEL and the mitochondrial hsp60, with an evolutionary link to thermophilic archaebacteria [32"]. This proliferation in mycobacterial (see above) and mammalian hsp60 sequence provides considerable scope for further epitope mapping and renewed searches for novel patterns of hsp60 autoreactivity.
Hsp, y8 T cells and self-reactivity One of the most interesting theories arising from the finding that hsp are antigens is the suggestion that the immune system may use changes in expression of self hsp as a signal for the detection and elimination of abnormal (malignant, infected, etc.) cells [33]. Identification of a subset of mouse y8 T cells stimulated by a peptide determinant conserved between mycobacterial and mammalian hsp60 has provided a potential participant for this type of 'immune surveillance' system [34]. In the past year it has been demonstrated that hsp60-reactive cells are present as a major subset (10-20%) of the total mouse adult 78 T-cell repertoire [35"], and that they may provide some protection against Listeria monocyt~ genes infection [36"]. A major remaining challenge is to determine whether the 78 response to infection is a 'conventional' recognition of a bacterial antigen, or is in fact autorecognition of a stressed self cell. A further intriguing observation is that the expression of mouse class Ib proteins, which may well be antigen-presenting molecules for 78 T cells, is regulated by heat shock and hsp [37]. Models based on the recognition of stressed cells by 78 T cells should include changes in the cell-surface expression of particular antigen-presenting molecules as well as changes in the overall levels of stress-induced antigens as possible recognition signals. The extent to which human 78 T cells parallel their mouse counterparts in responses to hsp remains unclear. Co-localization of 78 T cells and hsp60-expressing oligodendrocytes in chronic brain lesions has led to the suggestion that human hsp60-reactive 78 T cells are important in the pathogenesis of multiple sclerosis [38].
Conclusions Cohen and Young [39"] have suggested that two types of immune response to hsp (and other self-like antigens) can be envisaged, with foreign epitopes inducing a conventional aggressive response to infection, and conserved epitopes being recognized by a tightly regulated autoreactive T-cell population. Assuming that this system functions well in the vast majority of cases, one would predict the immune response to hsp from pathogens to be dominated by the recognition of non-conserved determinants, and indeed, this appears to be in accord with most of the experimental evidence. Under most
Heat-shock proteins: immunity and autoimmunity Young circumstances there is no reason to think that this response is in any way detrimental to the host, but it is possible that normal regulation may break dov,;n in some infections. Triggering of a 'self-like' regulatory circuit by the foreign hsp could result in suppression of the immune response to the pathogen, whereas 'escape' of a self-reactive clone from regulation could contribute to immunopathological aspects of infection. It is attrac rive to propose that an 'autoimmune' component of this type is associated with several bacterial diseases (reactive arthritis, Lyme disease, tuberculoid leprosy), but this remains open to experimental verification. It is surprising that conserved epitopes have been implicated in two instances of protective antibody responses to hsp [19,20 9 Perhaps antigen presentation by autoreactive B cells is involved in this response [39~ Recent results from rodent models of autoimmunity continue to support the concept that appropriate presentation of hsp60 provides a mechanism for manipulation of autoimmune phenomena, but the notion of rheumatoid arthritis as a simple manifestation of hsp60 autoimmunity has suffered some erosion. Hsp are not unique in being targets of autoreactive T cells although the potential for stress related changes in their exposure to the immune system certainly enhances their interest as autoantigens. The challenge for immunologists is to understand how such autoreactive T cells are regulated as part of the normal immune response and to determine whether or not these cells do in fact play a role in the pathology of human autoimmune disease.
Acknowledgements
5.
KIKUTALC, PUOLUKKAINENM, KUO CC, CAMPBELL LL: Isolation and Sequence Analysis of the Chlamydia pneumoniae GroE Operon. Infect Immun 1991, 59:4665-4669.
SHANAFELTM-C, HINDERSSONP, SODERBERGC, MENSI N, TURCK CW, WEBB D, YSSEL H, PELTZ G; T Cell and Antibody Reactivity with the Borrelia burgdorferi 60-kDa Heat Shock Protein in Lyme Arthritis. J Immunol 1991, 146:3985-3992. The sequence of B. burgdorferi GroEL is reported along with data on antibody responses in patient sera and mapping of an epitope recognized by a T-cell clone. 6. 9
7. 9
BURNSDL, GOULD-KOSTKAJL, KESSEL M, ANCINIEGAJI2 Purification and Immunological Characterization of a GroEL-Uke Protein from Bordetella pertussis. Infect Immun 1991, 59:1417-1422. Vaccination with purified GroEL provided only a small amount of protection against an aerosol challenge with B. pertussia 8.
STEINMETZI, RHEINHEIMERC, HUBNER I, BITTER-SUERMANND: Genus-specific Epitope on the 60-kilodalton Legionella Heat Shock Protein Recognized by a Monoclonal Antibody. J Clin Microbiol 1991, 29:346-354.
9.
SIPOS A, KLOCKE M, FROSCH M: C l o n i n g and Sequencing of the Genes Coding for the 10- and 60-kDa Heat Shock Proteins from Pseudomonas aeruginosa and Mapping of a Species-specific Epitope. Infect Immun 1991, 59:3219-3226.
10.
ADELEYETA, COLSTONMJ, BUTLER R, JENNER PJ: The Antibody Repertoire to Proteins of Mycobacterium leprae. Genetic Influences at the Antigen and Epitope Level. J Immunol 1991, 147:1947-1953.
11.
MAZOD1ERP, GUGLIELMIG, DAVIESJ, THOMPSON CJ: Characterization of the groEL-like Genes in Streptomyces albux J Bacteriol 1991, 173:7382-7386.
12. 99
R1NKEDE WIT T, BEKELIE S, OSLANDA, MIKO TL, HERMANSPW, VAN SOOUNGEN D, DRIJFHOUTJ-W, SCHON1NGHR, JANSONAAM, THOLE JER: Mycobacteria Contain Two GroEL Genes. Mol Microbiol 1992, in press. Reports the identification of a second groEL gene in M leprae following characterization of clones isolated from a recombinant DNA expression library using sera from leprosy patients. This gene is located next to the groES gene on the mycobacterial chromosome. 13.
MEHRAV, BLOOM BR, BAJARDI AC, GRISSO CL, SIELING PA, ALLANDD, CONVITJ, FAN X, HUNTERSW, BRENNANPJ, ETAL.: A Major T Cell Antigen of Mycobacterium leprae is a lO-kD Heat-shock Cognate Protein. J Exp Med 1992, 175:275-284. Analysis based on T-cell recognition of antigens separated by two-dimensional gel electrophoresis led to the identification of GroES as a prominent antigen of a/L leprae. 99
I am grateful to Ann Rees, Jelle Thole, willi Bom and Graham Rook for their thoughtful comments on the manuscript.
References and recommended reading Papers of particular interest, published within the annual period of re view, have been highlighted as: 9 of special interest 99 of outstanding interest 1.
YOUNGDB, MEHLERTA, SMITH DF: Stress Proteins and Infectious Diseases. In Stress Proteins in Biology and Medicine. Edited by Morimoto RI, Tissieres A, Georgopoulos C. New York: Cold Spring Harbor Laboratory Press; 1990:131-165.
2.
COHENIR: Autoimmunity to Chaperonins in the Pathogencsis of Arthritis and Diabetes. Annu Rev Immunol 1991, 9:567 589.
3.
MORRISONRP, BELLANDRJ, LYNGK, CALDWELLHD: Chlamydial Disease Pathogenesis: the 57-kD Chlamydial Hypersensitivity Antigen is a Stress Response Protein. J Exp Med 1989, 170:1271 1283.
4.
CERRONEMC, ME JJ, STEPHENS RS: Cloning and Sequence of the Gene for Heat Shock Protein 60 from Chlamydia trachomatis and Immunological Activity of the Protein. Infect Immun 1991, 59:79-90.
14.
VERBONA~ HARTSKEERLRA, KOLK AHJ: Murine and H u m a n B
Cell Epitope Mapping of the Mycobacterium tuberculosis lO-kD Heat Shock Protein Using Overlapping Peptides. Clin Exp Immunol 1991, 86:6-12. 15.
LUBBEN TH, GATENTBy AA, DONALDSON GK, LOmMER GH, VITTANEN PV: Identification of a groES-like Chaperonin in Mitochondria that Facilitates Protein Folding. Proc Natl Acad Sci USA 1990, 87:7683-7687.
16.
MCKENZ1E KR, ADAMS E, BRITrON WJ, GARSIA RJ, BASTEN A~ Sequence and Immunogenicity of the 70-kDa Heat Shock Protein of Mycobacterium leprae. J lmmunol 1991, 147:312319.
17.
DAVENPORTMP, MCKENZIE KR, BASTEN A, BRITrON WJ: The Variable C-terminal Region of the Mycobacterium leprae 70-kilodalton Heat Shock Protein is the Target for Humoral Immune Responses. Infect lmmun 1992, 60:1170-1177.
18.
ELSAGHIERAAF, WILK/NSEGL, MEHROTRAPK, J1NDALS, IVANYIJ: Elevated Antibody Levels to Stress Protein HSP70 in SmearNegative Tuberculosis. lmmunol Infect Dis 1991, 1:323-328.
19.
ZHONGG, BRUNHAMRC: Antigenic Analysis of the Chlamydial 75-kilodalton Protein. Infect Immun 1992, 60:1221-1224.
20. 9
MATrHEWSRC, BURNIE JP, HOWAT D, ROWLAND T, WALTON F: Autoantibody to Heat Shock Protein 90 can Mediate
399
400
Immunity
to
infection
Protection Against Systemic Candidosis. Immunology 1991, 74:20-24. Antibodies in patient sera and a protective monoclonal antibody recognize a highly conserved epitope on C. albicans hsp90. 21.
HOGERVORSTEJM, BOO(; CJP, WAGENAARJPA, WAUBEN MHM, VAN DER ZEE R, VAN EDEN W: T Cell Reactivity to an Epitope of the Mycobacterial 65-kDa Heat Shock Protein (hsp65) Corresponds With Arthritis Susceptibility in Rats and is Regulated by hsp65-specific Cellular Responses. Eur J Immunol 1991, 21:1289-'1296. Reports proliferative T-cell responses to peptide epitope 180-188 in rats that are susceptible to the development of adjuvant-induced arthritis and the absence of these responses in rats that are resistant to disease. 9
22.
HOGERVORSTEJM, SCHOULr L, WAGENAARJPA, BOOG CJP, SPAAN WJM, VAN EMBDENJDA, vAN EDEN W: Modulation of Experimental Autoimmunity: Treatment of Adjuvant Arthritis by Immunization with a Recombinant Vaccinia Virus. Infect Immun 1991, 59:2029-2035.
ELIASD, RESHEFT, BIRKOS, VANDER ZEE R, WALKERMD, COHEN IR: Vaccination Against Autoimmune Mouse Diabetes with a T-cell Epitope of the Human 65-kDa Heat Shock Protein. Proc Natl Acad Sci USA 1991, 88:3088-3091. Vaccination with a synthetic peptide from a conserved region of the hsp60 protein protects NOD mice against the development of diabetes. 23. 99
24.
RES PCM, ORSINI DLM, vAN LAARJM, JANSON AAM, ABOU-ZE1D C, DE VRIES RRP: Diversity in Antigen Recognition by Mycobacterium tuberculosis-reactive T Cell Clones from the Synovial Fluid of Rheumatoid Arthritis Patients. Eur J Immunol 1991, 21:1297-1302.
25. .
FISCHERHP, SHARROCKCEM, COLSTON MJ, PANAY[ GS: Limiting Dilution Analysis of Proliferative T Cell Responses to Mycobacterial 65-kDa Heat-Shock Protein Fails to Show Significant Frequency Differences Between Synovial Fluid and Peripheral Blood of Patients with Rheumatoid Arthritis. Eur J Immunol 1991, 21:2937-2941. Reports that limiting dilution analysis shows no difference in the relative frequency of 65 kD antigen-reactive T cells between synovial fluid and blood of patients with rheumatoid arthritis, or between blood samples from arthritis patients and control subjects. 26.
27.
KAUFMANNSHE, VATH U, THOLE JER, VAN EMBDEN JDA, EMMRICH F: Enumeration of T Cells Reactive with Mycobacterium tuberculosis Organisms and Specific for the Recombinant 64-kDa Protein. Eur J Immunol 1987, 17:351057. VAN OERS M, P1NKSTER J, ZEIJLERMAKERW: Quantitation of Antigen-reactive Cells Among Human T Lymphocytes. Eur J lmmunol 1978, 8:477-484.
28. 9
HERMANN E, LOKSE AW, VAN DER ZEE R, VAN EDEN W, MAYET WJ, PROBST P, PORALLA T, ZUM BUSCHENFEIJ)E KHM, FLEISCHER B: Synovial Fluid-derived Yersinia-reactive T Cells Responding to Human 65-kDa Heat-shock Protein and Heat-stressed Antigen-presenting Cells. Eur J Immunol 1991, 21:2139-2143. An hsp60 autoreactive T-cell clone isolated from synodal fluid of a reactive arthritis patient was characterized. 29.
POPE RM, LOVIS RIM, GUPTA RS: Activation of Synovial Fluid T Lymphocytes by 60-kD Heat-Shock Proteins in Patients with Inflammatory Synovitis. Arthritis Rheum 1992, 35:43-48.
30. 99
DE GRAEFF-MEEDERER, VAN DER ZEE R, RIJKES GT, SCHUURMAN H-J, KUIS W, BIJLSMAJMJ, ZEGERS BJM, VAN EDEN W: Recogni-
tion of Human 60 kD Heat Shock protein by Mononuclear Cells from Patients with Juvenile Chronic Arthritis. Lancet 1991, 337:1368-1372. T cells from synovial fluid of patients with juvenile chronic arthritis show strong autoreactivity to human hsp60, in contrast to similar samples from patients with rheumatoid arthritis. 31.
SIOUDM, KJELDSEN-KRAGLJ, QUAYLE AJ, WlKER HG, sOKSKAAR D, NATVIGJB, FORRE O: Immune Responses to 18.6 and 30-
kDa Mycobacterial Antigens in Rheumatoid Patients, and V~ Usage by Specific Synovial T-cell Lines and Fresh T Cells. Scand J tmmunol 1991, 34:803-812. 32. 9
TRENTJD, NIMMESGERNE, WALLJS, HARTL F-U, HORWICH aL: A Molecular Chaperone from a Thermophilic Archaebacterium is Related to the Eukaryotic Protein t-Complex Polypeptide-1. Nature 1991, 354:490-493. Identification of TCP-1 as a member of the hsp60/chaperonin family by sequence comparison with a molecular chaperone from Sulfolobus shibatae. 33.
YOUNGRA, ELL1OTr TJ: Stress Proteins, Infection and Immune Surveillance. Cell 1989, 59:5-8.
34.
BORNW, HALL L, DALLASA, BOYMELJ, SHINN1CKT, YOUNG D, BRENNAN P, O'BRIEN R: Recognition of a Peptide Antigen by Heat Shock Reactive "y8 T Lymphocytes. Science 1990, 249:67-69.
35.
O'BRIENRL, FU Y-X, CRANFILLR, DALLASA, ELLIS C, REARDON C, LANG J, CARDING SR, KUBO R, BORN W: HSP-60 Reactive y8 Cells: a Large, Diversified T Lymphocyte Subset with Highly Focused Specificity. Proc Natl Acad Sci USA 1992, 89:4348-4352. The authors demonstrate that hsp60-reactive y8 T cells expressing Vy1 and V56 genes make up 1(~20% of the total adult y8 T-cell repertoire in mice by the generation of T-cell hybridomas 9
36. 9
HIROMATSUK, YOSHIKAIY, MATSUZAKIG, OHGA S, MURAMOR~K, MATSUMOTOK, BLUESTONEJA, NOMOTO K: A Protective Role for y8 T Cells in Primary Infection with Listeria m o n o c ~ togenes in Mice. J Exp Meal 1992, 175:49-56. T8 T cells reactive with the mycobacterial 65 kD antigen accumulate at the site of Listeria sp. infection. Depletion of 78 T cells using monoclonal antibodies increases the bacterial multiplication. 37.
IMANIF, SOLOSKIMJ: Heat Shock Proteins can Regulate Expression of the Tla Region-encoded Class lb Molecule Qa-1. Proc Natl Acad Sci USA 1991, 88:10475-10479.
38.
SEIJVlAJK, BROSNANCF, RAINE CS: Colocalization of Lymphocytes Bearing 78 T-Cell Receptor and Heat Shock Protein 65 + Oligodendrocytes in Multiple Sclerosis. Proc Natl Acad Sci USA 1991, 88:6452q5456.
39. 9
COHENIR, YOUNG DB: Autoimmunity, Microbial Immunity and the Immunological Homunculus. Immunol Today 1991, 12:10~110. Responses to hsp in infection and autoimmunity are considered in the context of a general discussion of immune responses to conserved anti gens.
DB Young, MR(: Tuberculosis and Related Infections Unit, RPMS, Hammersmith Hospital, Ducane Road, Ixmdon W12 OHS, UK.
Seminars in Immunology 3, Current Topics in Microbiology and Immunology 167 and Immunological Reviews 121 providing entire issues on this topic. The present review focuses on recent primary publications, but the wide range of excellent in-depth reviews have provided a comprehensive analysis of the subject.
Hsp and the immune response to infection A large amount of work on the design of novel diagnostic probes and 'subunit' vaccines for infectious diseases has involved the identification of the individual components of pathogens that trigger immune responses. With a vast array of potential antigens from a protozoan parasite or pathogenic bacterium, it is attractive to speculate that the immune system might follow some discemable pattern in selecting particular targets for recognition. However, review of recent studies on individual pathogens does not provide much support for this proposal; for example, the list of antigens identified from blood-stage malaria parasites or mycobacterial pathogens seems bewildering in extent and diversity. Nevertheless, an overview of a vari-
ety of diseases has emphasized the antigenicity of members of conserved hsp families [1]. The identification of hsp as 'generic antigens' has prompted the suggestion that a study of their immune recognition may provide a useful comparison between different diseases. Differences in the immune response to hsp, in terms of the recognition of different epitopes or the involvement of functionally distinct lymphocyte subsets, might indicate differences in the way that particular pathogens interact with the immune system and may be useful in diagnosis. Similarities might suggest immune mechanisms common to different infections. Several studies over the last year have involved further characterization of the immune responses to bacterial hsp. The bacterial m e m b e r of the 60 kD hsp family, often referred to as GroEL, has been implicated in harmful T-cell responses during chlamydial infection [3]. Initial studies involved characterization of the antigen from Chlam3* alia psittaci and two further studies extended this to sequencing of groEL genes from the human pathogens C trachomatis and C. pneumonia [4,5]. By analogy with chlamydia, it is possible that immune responses to hsp60 may also play a role in the pathogenicity of Borrelia burgdorferi, the spirochete responsible for Lyme arthritis. A limited immunological characterization demonstrated the presence of antibodies in sera from Lyme disease patients and a T-cell clone identified a speciesspecific determinant on the B. burgdorferi GroEL [6*]. Burns et al. [7"] purified GroEL from Bordetellapertussis and found that standard diptheria-pertussis-tetanus vaccination induced an antibody response to hsp60 which included an element of crossreactivity to the mammalian homologue. Vaccination with purified GroEL provided only slight protection against a challenge with B. pertussis in animal models, and the authors speculate that its inclusion in vaccine preparations may be more likely to contribute to harmful side effects than to protective immunity [7~ Studies of GroEL from Legionella sp. [8] and from Pseudomonas aeruginosa [9] focused on the identification of genus-specific and species-specific epitopes recognized by monoclonal antibodies, while an
Abbreviations hsp~heat-shock protein; NOD--non-obese diabetic; PPD~purified protein derivative. 396
(g) Current Biology Ltd ISSN 0952-7915
Heat-shock proteins:immunityand autoimmunityYoung 397 extensive synthetic peptide analysis was used to examine genetic effects on the antibody responses to Mycobacterium leprae GroEL in mice [10]. An unexpected aspect of the bacterial GroEL studies was the finding of a second GroEL protein in some organisms. This was reported initially in Streptomyces [11] but has also been found in M. tuberculosis [ARM Coates, personal communication] and in M. leprae [12..]. GroEL is a molecular chaperone involved in folding, assembly and intracellular transport of proteins and has a functional interaction with a 10 kD hsp called GroES. An analysis of proliferative T-cell responses in leprosy patients led to the identification of M. leprae GroES as a major antigen, which was recognized by as many as one in three of the M. leprae-reactive T cells in peripheral blood of some patients [13o.]. In contrast to GroEL [10], attempts to map antibody responses to the mycobacterial GroES, using synthetic peptides, were rather unsuccessful [14]. Escherichia coli GroES is also much less effective than GroEL in the induction of antibodies (A Mehlert and DB Young, unpublished data), suggesting that there may be some qualitative difference in the immunogenicity of the two classes of protein. It is not yet known whether 'GroES' in eukaryotic cells is structurally as well as func tionally homologous with bacterial GroES [15] and the possibility of autoreactive responses to GroES has not been assessed. It will certainly be interesting, however, to look for T-cell responses to GroES in association with other bacterial infections. Another major antigenic hsp with a chaperone function is DnaK, the bacterial member of the hsp70 family. DnaK from M. leprae has been studied in detail over the past year by molecular and immunological analysis [16,17]. Previous findings of antibody and T-cell reactivity in leprosy patients were confirmed using recombinant antigen, with antibody responses being preferentially directed towards the variable carboxyl-terminal region of the protein [17]. Antibody responses to the corresponding recombinant M. tuberculosisDnaK were also analyzed using sera from tuberculosis patients [18]. Anti-DnaK antibodies were detected even in patients with a low bacterial load, suggesting that these may have some diagnostic use, in spite of a high level of autoantibodies detected using recombinant human hsp70 as antigen [18]. In contrast to GroEL, immune responses to chlamydial DnaK are associated with protection against disease. A synthetic peptide-mapping approach was used to localize two epitopes from chlamydial DnaK exposed on the surface of elementary bodies and recognized by neutralizing antibodies [19]. One of the epitopes was mapped in a conserved region of the protein (seven out of 10 residues identical to human hsp70) and future work may determine whether or not the protective antibodies also recognize corresponding regions from other hsp70 proteins. Finally, an intriguing study of antibody responses during systemic candidosis implicated hsp90 of Candida albicans as an important immune target capable of eliciting protective antibodies. Peptide mapping in this case again demonstrated that a neutralizing monoclonal antibody, as
well as patient antisera, recognized a highly conserved autoreactive, determinant of the protein [20~ The mechanism of the protective effect of these antibodies remains to be elucidated.
Hsp and animal models of autoimmunity The importance of hsp in animal models of autoimmunity was first recognized by the observation that autoreactive T-cell clones capable of transferring pathogenic symptoms of adjuvant arthritis in the rat model were directed to mycobacterial GroEL, the '65kD antigen'. Subsequently, it was found that vaccination with the purified mycobacterial antigen prevented the development of arthritis in rodent models following challenge not only with mycobacteria, but also with streptococcal cell walls, collagen or pristane. Interest focused on one particular epitope on the protein, amino acid residues 180-188, that was recognized by both protective and arthritogenic T cells and that could itself induce protection against adjuvant arthritis when administered as a synthetic peptide vaccine. This epitope was not conserved in the corresponding rodent hsp60 protein, and the mechanism of the protective effect was unclear (reviewed in [2] ). Several studies over the past year have lent further support to the proposed importance of the 65 kD antigen in adjuvant athritis. Hogervorst et aL [21 ~ demonstrated that T-cell proliferation in response to the 180-188 peptide was correlated with susceptibility to disease. T cells from resistant (Fischer) rats immunized with M. tuberculosis failed to proliferate to peptide 180-188, while the positive response by susceptible (Lewis) rats was inhibited by prior vaccination with the purified antigen, or peptide [21.]. The authors speculate that this may represent a difference in T-cell receptor repertoire between the two strains [21.]. Presentation of the 65kD antigen by vaccinia virus resembled vaccination with the purified antigen in generating a protective, rather than pathological, response [22]. Immune responses to the 65 kD antigen have also been implicated in regulation of the development of insulindependent diabetes in the non-obese diabetic (NOD) strain of mice [2]. Elias et al. [23**] went on to demonstrate that here, too, a single peptide determinant was recognized by diabetogenic clones and could confer protection in vaccination experiments. In this case the epitope (residues 437-460) was identical in all but one of its amino acids between bacterial and mammalian hsp60, suggesting that a model of 'antigenic mimicry' between corresponding hsp could account for the observations.
Hsp and human autoimmune disease Results from animal models prompted many investigators to look for an association with immune responses to hsp in human autoimmune diseases (reviewed in [1,2]). In
398
Immunityto infection particular, several reports described an enhanced proliferative response to the mycobacterial 65 kD antigen in experiments using T cells from synovial fluid of patients with rheumatoid or reactive arthritis and, in a similar vein, anti-hsp60 autoreactive T-cell responses were demonstrated (although their association with autoimmune disease was not established). Several publications over the last year have extended our knowledge in this area. The original conclusion that T-cell responses to mycobacterial 65 kD are elevated in rheumatoid synovia has been questioned in two ways. First, it has been suggested that this is not specific for the hsp and that, in fact, the same phenomenon can be demonstrated for other my cobacterial antigens [24]. Second, a careful study ofT-cell precursor frequency, comparing T cells from synovia and from peripheral blood, but using the same population of antigen-presenting cells in each case, led to the conclusion that the elevated response reported for synovial cells can be attributed to differences in antigen-presenting cell populations in the two compartments rather than to an altered distribution of T cells [25"]. This report deserves a special commendation in providing quantitative data on the 'immunodominance' of the mycobacterial 65 kD antigen. Most analyses of 65 kD responses in humans have been based on T-call clones or lines and, as a criterion for immunodominance, have relied on the oft-quoted result of mouse experiments showing that 65 kD reactivity accounts for one in five of all mycobacteria-reactive T cells [26]. Excluding one very low responder among the 10 patients in the present study, the frequency of 65kD-reactive T cells ranged from 1/2490 to 1/9600, with a mean of around 1/5 000 [25"]. By comparison, purified protein derivative (PPD)-reactivity in the same patients ranged from 1/300 to 1/8 030, with a mean of approximately 1/2 000. If PPD is considered to comprise a cross-section of mycobacterial antigens, these results suggest that the relative ratio of 65 kD-reactive to mycobacteria-reactive T cells is, in fact, broadly similar between mouse and man. The overall frequency of 65 kDreactive cells is within the range previously reported for tetanus toxoid (1/750 to 1/11 500), and is clearly lower than that of alloantigen-reactivity (1/200 to 1/600) [27]. No significant difference was found between control and rheumatoid arthritis patients [25"]; it would be interesting to see whether the numbers go up or down, during mycobacterial infection. Meanwhile, several other studies addressed the question of autoreactive hsp60 responses by synovial T cells. An autoreactive clone, capable of recognizing heat-stressed presenting cells in the absence of exogenous antigen, was isolated from a patient with Yersinia-related reactive arthritis [28.], but the bulk of the antimycobacterial response in rheumatoid synovia was found to be specific for the bacterial rather than the human hsp [29]. In contrast, strong responses to human hsp60 were found in synovial T cells from patients with juvenile chronic arthritis [30"~ suggesting a possible correlation with hsp autoreactivity in some forms of the disease. Responses to other, non-hsp, mycobacterial antigens have also been reported in such patients [31].
Hsp60 was initially identified in the mitochondria of mammalian cells, but it has recently been demonstrated that a cytoplasmic protein, referred to as 'TCP-I' in the mouse system, also belongs to the same chaperone family as GroEL and the mitochondrial hsp60, with an evolutionary link to thermophilic archaebacteria [32"]. This proliferation in mycobacterial (see above) and mammalian hsp60 sequence provides considerable scope for further epitope mapping and renewed searches for novel patterns of hsp60 autoreactivity.
Hsp, y8 T cells and self-reactivity One of the most interesting theories arising from the finding that hsp are antigens is the suggestion that the immune system may use changes in expression of self hsp as a signal for the detection and elimination of abnormal (malignant, infected, etc.) cells [33]. Identification of a subset of mouse y8 T cells stimulated by a peptide determinant conserved between mycobacterial and mammalian hsp60 has provided a potential participant for this type of 'immune surveillance' system [34]. In the past year it has been demonstrated that hsp60-reactive cells are present as a major subset (10-20%) of the total mouse adult 78 T-cell repertoire [35"], and that they may provide some protection against Listeria monocyt~ genes infection [36"]. A major remaining challenge is to determine whether the 78 response to infection is a 'conventional' recognition of a bacterial antigen, or is in fact autorecognition of a stressed self cell. A further intriguing observation is that the expression of mouse class Ib proteins, which may well be antigen-presenting molecules for 78 T cells, is regulated by heat shock and hsp [37]. Models based on the recognition of stressed cells by 78 T cells should include changes in the cell-surface expression of particular antigen-presenting molecules as well as changes in the overall levels of stress-induced antigens as possible recognition signals. The extent to which human 78 T cells parallel their mouse counterparts in responses to hsp remains unclear. Co-localization of 78 T cells and hsp60-expressing oligodendrocytes in chronic brain lesions has led to the suggestion that human hsp60-reactive 78 T cells are important in the pathogenesis of multiple sclerosis [38].
Conclusions Cohen and Young [39"] have suggested that two types of immune response to hsp (and other self-like antigens) can be envisaged, with foreign epitopes inducing a conventional aggressive response to infection, and conserved epitopes being recognized by a tightly regulated autoreactive T-cell population. Assuming that this system functions well in the vast majority of cases, one would predict the immune response to hsp from pathogens to be dominated by the recognition of non-conserved determinants, and indeed, this appears to be in accord with most of the experimental evidence. Under most
Heat-shock proteins: immunity and autoimmunity Young circumstances there is no reason to think that this response is in any way detrimental to the host, but it is possible that normal regulation may break dov,;n in some infections. Triggering of a 'self-like' regulatory circuit by the foreign hsp could result in suppression of the immune response to the pathogen, whereas 'escape' of a self-reactive clone from regulation could contribute to immunopathological aspects of infection. It is attrac rive to propose that an 'autoimmune' component of this type is associated with several bacterial diseases (reactive arthritis, Lyme disease, tuberculoid leprosy), but this remains open to experimental verification. It is surprising that conserved epitopes have been implicated in two instances of protective antibody responses to hsp [19,20 9 Perhaps antigen presentation by autoreactive B cells is involved in this response [39~ Recent results from rodent models of autoimmunity continue to support the concept that appropriate presentation of hsp60 provides a mechanism for manipulation of autoimmune phenomena, but the notion of rheumatoid arthritis as a simple manifestation of hsp60 autoimmunity has suffered some erosion. Hsp are not unique in being targets of autoreactive T cells although the potential for stress related changes in their exposure to the immune system certainly enhances their interest as autoantigens. The challenge for immunologists is to understand how such autoreactive T cells are regulated as part of the normal immune response and to determine whether or not these cells do in fact play a role in the pathology of human autoimmune disease.
Acknowledgements
5.
KIKUTALC, PUOLUKKAINENM, KUO CC, CAMPBELL LL: Isolation and Sequence Analysis of the Chlamydia pneumoniae GroE Operon. Infect Immun 1991, 59:4665-4669.
SHANAFELTM-C, HINDERSSONP, SODERBERGC, MENSI N, TURCK CW, WEBB D, YSSEL H, PELTZ G; T Cell and Antibody Reactivity with the Borrelia burgdorferi 60-kDa Heat Shock Protein in Lyme Arthritis. J Immunol 1991, 146:3985-3992. The sequence of B. burgdorferi GroEL is reported along with data on antibody responses in patient sera and mapping of an epitope recognized by a T-cell clone. 6. 9
7. 9
BURNSDL, GOULD-KOSTKAJL, KESSEL M, ANCINIEGAJI2 Purification and Immunological Characterization of a GroEL-Uke Protein from Bordetella pertussis. Infect Immun 1991, 59:1417-1422. Vaccination with purified GroEL provided only a small amount of protection against an aerosol challenge with B. pertussia 8.
STEINMETZI, RHEINHEIMERC, HUBNER I, BITTER-SUERMANND: Genus-specific Epitope on the 60-kilodalton Legionella Heat Shock Protein Recognized by a Monoclonal Antibody. J Clin Microbiol 1991, 29:346-354.
9.
SIPOS A, KLOCKE M, FROSCH M: C l o n i n g and Sequencing of the Genes Coding for the 10- and 60-kDa Heat Shock Proteins from Pseudomonas aeruginosa and Mapping of a Species-specific Epitope. Infect Immun 1991, 59:3219-3226.
10.
ADELEYETA, COLSTONMJ, BUTLER R, JENNER PJ: The Antibody Repertoire to Proteins of Mycobacterium leprae. Genetic Influences at the Antigen and Epitope Level. J Immunol 1991, 147:1947-1953.
11.
MAZOD1ERP, GUGLIELMIG, DAVIESJ, THOMPSON CJ: Characterization of the groEL-like Genes in Streptomyces albux J Bacteriol 1991, 173:7382-7386.
12. 99
R1NKEDE WIT T, BEKELIE S, OSLANDA, MIKO TL, HERMANSPW, VAN SOOUNGEN D, DRIJFHOUTJ-W, SCHON1NGHR, JANSONAAM, THOLE JER: Mycobacteria Contain Two GroEL Genes. Mol Microbiol 1992, in press. Reports the identification of a second groEL gene in M leprae following characterization of clones isolated from a recombinant DNA expression library using sera from leprosy patients. This gene is located next to the groES gene on the mycobacterial chromosome. 13.
MEHRAV, BLOOM BR, BAJARDI AC, GRISSO CL, SIELING PA, ALLANDD, CONVITJ, FAN X, HUNTERSW, BRENNANPJ, ETAL.: A Major T Cell Antigen of Mycobacterium leprae is a lO-kD Heat-shock Cognate Protein. J Exp Med 1992, 175:275-284. Analysis based on T-cell recognition of antigens separated by two-dimensional gel electrophoresis led to the identification of GroES as a prominent antigen of a/L leprae. 99
I am grateful to Ann Rees, Jelle Thole, willi Bom and Graham Rook for their thoughtful comments on the manuscript.
References and recommended reading Papers of particular interest, published within the annual period of re view, have been highlighted as: 9 of special interest 99 of outstanding interest 1.
YOUNGDB, MEHLERTA, SMITH DF: Stress Proteins and Infectious Diseases. In Stress Proteins in Biology and Medicine. Edited by Morimoto RI, Tissieres A, Georgopoulos C. New York: Cold Spring Harbor Laboratory Press; 1990:131-165.
2.
COHENIR: Autoimmunity to Chaperonins in the Pathogencsis of Arthritis and Diabetes. Annu Rev Immunol 1991, 9:567 589.
3.
MORRISONRP, BELLANDRJ, LYNGK, CALDWELLHD: Chlamydial Disease Pathogenesis: the 57-kD Chlamydial Hypersensitivity Antigen is a Stress Response Protein. J Exp Med 1989, 170:1271 1283.
4.
CERRONEMC, ME JJ, STEPHENS RS: Cloning and Sequence of the Gene for Heat Shock Protein 60 from Chlamydia trachomatis and Immunological Activity of the Protein. Infect Immun 1991, 59:79-90.
14.
VERBONA~ HARTSKEERLRA, KOLK AHJ: Murine and H u m a n B
Cell Epitope Mapping of the Mycobacterium tuberculosis lO-kD Heat Shock Protein Using Overlapping Peptides. Clin Exp Immunol 1991, 86:6-12. 15.
LUBBEN TH, GATENTBy AA, DONALDSON GK, LOmMER GH, VITTANEN PV: Identification of a groES-like Chaperonin in Mitochondria that Facilitates Protein Folding. Proc Natl Acad Sci USA 1990, 87:7683-7687.
16.
MCKENZ1E KR, ADAMS E, BRITrON WJ, GARSIA RJ, BASTEN A~ Sequence and Immunogenicity of the 70-kDa Heat Shock Protein of Mycobacterium leprae. J lmmunol 1991, 147:312319.
17.
DAVENPORTMP, MCKENZIE KR, BASTEN A, BRITrON WJ: The Variable C-terminal Region of the Mycobacterium leprae 70-kilodalton Heat Shock Protein is the Target for Humoral Immune Responses. Infect lmmun 1992, 60:1170-1177.
18.
ELSAGHIERAAF, WILK/NSEGL, MEHROTRAPK, J1NDALS, IVANYIJ: Elevated Antibody Levels to Stress Protein HSP70 in SmearNegative Tuberculosis. lmmunol Infect Dis 1991, 1:323-328.
19.
ZHONGG, BRUNHAMRC: Antigenic Analysis of the Chlamydial 75-kilodalton Protein. Infect Immun 1992, 60:1221-1224.
20. 9
MATrHEWSRC, BURNIE JP, HOWAT D, ROWLAND T, WALTON F: Autoantibody to Heat Shock Protein 90 can Mediate
399
400
Immunity
to
infection
Protection Against Systemic Candidosis. Immunology 1991, 74:20-24. Antibodies in patient sera and a protective monoclonal antibody recognize a highly conserved epitope on C. albicans hsp90. 21.
HOGERVORSTEJM, BOO(; CJP, WAGENAARJPA, WAUBEN MHM, VAN DER ZEE R, VAN EDEN W: T Cell Reactivity to an Epitope of the Mycobacterial 65-kDa Heat Shock Protein (hsp65) Corresponds With Arthritis Susceptibility in Rats and is Regulated by hsp65-specific Cellular Responses. Eur J Immunol 1991, 21:1289-'1296. Reports proliferative T-cell responses to peptide epitope 180-188 in rats that are susceptible to the development of adjuvant-induced arthritis and the absence of these responses in rats that are resistant to disease. 9
22.
HOGERVORSTEJM, SCHOULr L, WAGENAARJPA, BOOG CJP, SPAAN WJM, VAN EMBDENJDA, vAN EDEN W: Modulation of Experimental Autoimmunity: Treatment of Adjuvant Arthritis by Immunization with a Recombinant Vaccinia Virus. Infect Immun 1991, 59:2029-2035.
ELIASD, RESHEFT, BIRKOS, VANDER ZEE R, WALKERMD, COHEN IR: Vaccination Against Autoimmune Mouse Diabetes with a T-cell Epitope of the Human 65-kDa Heat Shock Protein. Proc Natl Acad Sci USA 1991, 88:3088-3091. Vaccination with a synthetic peptide from a conserved region of the hsp60 protein protects NOD mice against the development of diabetes. 23. 99
24.
RES PCM, ORSINI DLM, vAN LAARJM, JANSON AAM, ABOU-ZE1D C, DE VRIES RRP: Diversity in Antigen Recognition by Mycobacterium tuberculosis-reactive T Cell Clones from the Synovial Fluid of Rheumatoid Arthritis Patients. Eur J Immunol 1991, 21:1297-1302.
25. .
FISCHERHP, SHARROCKCEM, COLSTON MJ, PANAY[ GS: Limiting Dilution Analysis of Proliferative T Cell Responses to Mycobacterial 65-kDa Heat-Shock Protein Fails to Show Significant Frequency Differences Between Synovial Fluid and Peripheral Blood of Patients with Rheumatoid Arthritis. Eur J Immunol 1991, 21:2937-2941. Reports that limiting dilution analysis shows no difference in the relative frequency of 65 kD antigen-reactive T cells between synovial fluid and blood of patients with rheumatoid arthritis, or between blood samples from arthritis patients and control subjects. 26.
27.
KAUFMANNSHE, VATH U, THOLE JER, VAN EMBDEN JDA, EMMRICH F: Enumeration of T Cells Reactive with Mycobacterium tuberculosis Organisms and Specific for the Recombinant 64-kDa Protein. Eur J Immunol 1987, 17:351057. VAN OERS M, P1NKSTER J, ZEIJLERMAKERW: Quantitation of Antigen-reactive Cells Among Human T Lymphocytes. Eur J lmmunol 1978, 8:477-484.
28. 9
HERMANN E, LOKSE AW, VAN DER ZEE R, VAN EDEN W, MAYET WJ, PROBST P, PORALLA T, ZUM BUSCHENFEIJ)E KHM, FLEISCHER B: Synovial Fluid-derived Yersinia-reactive T Cells Responding to Human 65-kDa Heat-shock Protein and Heat-stressed Antigen-presenting Cells. Eur J Immunol 1991, 21:2139-2143. An hsp60 autoreactive T-cell clone isolated from synodal fluid of a reactive arthritis patient was characterized. 29.
POPE RM, LOVIS RIM, GUPTA RS: Activation of Synovial Fluid T Lymphocytes by 60-kD Heat-Shock Proteins in Patients with Inflammatory Synovitis. Arthritis Rheum 1992, 35:43-48.
30. 99
DE GRAEFF-MEEDERER, VAN DER ZEE R, RIJKES GT, SCHUURMAN H-J, KUIS W, BIJLSMAJMJ, ZEGERS BJM, VAN EDEN W: Recogni-
tion of Human 60 kD Heat Shock protein by Mononuclear Cells from Patients with Juvenile Chronic Arthritis. Lancet 1991, 337:1368-1372. T cells from synovial fluid of patients with juvenile chronic arthritis show strong autoreactivity to human hsp60, in contrast to similar samples from patients with rheumatoid arthritis. 31.
SIOUDM, KJELDSEN-KRAGLJ, QUAYLE AJ, WlKER HG, sOKSKAAR D, NATVIGJB, FORRE O: Immune Responses to 18.6 and 30-
kDa Mycobacterial Antigens in Rheumatoid Patients, and V~ Usage by Specific Synovial T-cell Lines and Fresh T Cells. Scand J tmmunol 1991, 34:803-812. 32. 9
TRENTJD, NIMMESGERNE, WALLJS, HARTL F-U, HORWICH aL: A Molecular Chaperone from a Thermophilic Archaebacterium is Related to the Eukaryotic Protein t-Complex Polypeptide-1. Nature 1991, 354:490-493. Identification of TCP-1 as a member of the hsp60/chaperonin family by sequence comparison with a molecular chaperone from Sulfolobus shibatae. 33.
YOUNGRA, ELL1OTr TJ: Stress Proteins, Infection and Immune Surveillance. Cell 1989, 59:5-8.
34.
BORNW, HALL L, DALLASA, BOYMELJ, SHINN1CKT, YOUNG D, BRENNAN P, O'BRIEN R: Recognition of a Peptide Antigen by Heat Shock Reactive "y8 T Lymphocytes. Science 1990, 249:67-69.
35.
O'BRIENRL, FU Y-X, CRANFILLR, DALLASA, ELLIS C, REARDON C, LANG J, CARDING SR, KUBO R, BORN W: HSP-60 Reactive y8 Cells: a Large, Diversified T Lymphocyte Subset with Highly Focused Specificity. Proc Natl Acad Sci USA 1992, 89:4348-4352. The authors demonstrate that hsp60-reactive y8 T cells expressing Vy1 and V56 genes make up 1(~20% of the total adult y8 T-cell repertoire in mice by the generation of T-cell hybridomas 9
36. 9
HIROMATSUK, YOSHIKAIY, MATSUZAKIG, OHGA S, MURAMOR~K, MATSUMOTOK, BLUESTONEJA, NOMOTO K: A Protective Role for y8 T Cells in Primary Infection with Listeria m o n o c ~ togenes in Mice. J Exp Meal 1992, 175:49-56. T8 T cells reactive with the mycobacterial 65 kD antigen accumulate at the site of Listeria sp. infection. Depletion of 78 T cells using monoclonal antibodies increases the bacterial multiplication. 37.
IMANIF, SOLOSKIMJ: Heat Shock Proteins can Regulate Expression of the Tla Region-encoded Class lb Molecule Qa-1. Proc Natl Acad Sci USA 1991, 88:10475-10479.
38.
SEIJVlAJK, BROSNANCF, RAINE CS: Colocalization of Lymphocytes Bearing 78 T-Cell Receptor and Heat Shock Protein 65 + Oligodendrocytes in Multiple Sclerosis. Proc Natl Acad Sci USA 1991, 88:6452q5456.
39. 9
COHENIR, YOUNG DB: Autoimmunity, Microbial Immunity and the Immunological Homunculus. Immunol Today 1991, 12:10~110. Responses to hsp in infection and autoimmunity are considered in the context of a general discussion of immune responses to conserved anti gens.
DB Young, MR(: Tuberculosis and Related Infections Unit, RPMS, Hammersmith Hospital, Ducane Road, Ixmdon W12 OHS, UK.
