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CUNICAL INVESTIGATIONS

Incidence of Serum Precipitins Against Organic-Dust Antigens in Different Populations by Counterimmunoelectrophoresis* P. Phanuphak, AI.D.; John Salvaggio, M.D.; Jordan Fink, ~f.D.; and P. Kohler, M.D.

The incidence of serum anti dust and antifungal precipitins was determined by counterimmunoelectrophoresis in 317 atopic and nonatopic subjects of three geographic areas (north central, southern, and western United States). The selected lyophilized crude antigens employed were from house dust, Micropolyspora [aeni, Candida albicans, Alternaria tenuis, Aspergillus fumigatus, Puccinia coronata, Cantharellus cibarius, and Amborsia trifida. Antidust precipitins were detected with high frequency in atopic and nonatopic subjects of each geographic area (48 to 71 percent of different population subgroups). Precipitin reactions were generally intense and often multiple, in keeping with the marked heterogeneity of the crude dust antigen employed. Antidust precipitins were

also present in serum fractions precipitated with ammonium sulfate and in IgG-rich fractions obtained by gel filtration (Sephadex G-200) and diethylaminoethyl-cellulose chromatography. Precipitins against crude somatic fungal and actinomycetic antigens were detected with considerably less frequency in all populations surveyed, and antiragweed precipitins were not detected. Our results suggest that prolonged environmental exposure to diverse, ubiquitous organic dusts results in a "normal" serum precipitating-antibody response. They also extend our previous finding of a high precipitin response against organic dusts in residents of the Gulf south area compared to other geographic areas.

Serum precipitating antibodies against organic dust and fungal antigens have been thought to play an important role in the pathogenesis and diagnosis of hypersensitivity pneumonitis, bronchopulmonary allergic aspergillosis, and certain cases of late-onset bronchial asthma. 1,2 Because of the paucity of data concerning the presence of such

dence of antidust and antifungal precipitin detection might have been due in part to the humid semitropical local environment with known high atmospheric mold-spore content." Because of this possibility, we have now extended the precipitin survey to include populations from the north central, southern, and western United States.

For editorial comment, see page 749

precipitins in the population at large, we recently determined the incidence of such precipitins in groups of atopic and nonatopic residents of the Gulf area of the South by counterimmunoelectrophoresis." Results indicated that serum precipitins against organic dust were frequently present in this population, suggesting that their detection merely reflected prolonged environmental exposure to organic dusts. It remained possible, however, that our high incio From

the Departments of Medicine, Louisiana State University Medical Center, New Orleans; University of Colorado, Denver; and Medical College of Wisconsin, Milwaukee. Manuscript received April 8; revision accepted June 6. Reprint requests: Dr. Salvaggio, 1542 Tulane Avenue, New

Orleans 70112

CHEST, 68: 6, DECEMBER, 1975

MATERIALS AND METHODS

Study Subjects Sera were obtained from three groups of volunteer subjects in the Milwaukee, New Orleans, and Denver areas by each of the investigators, Subjects were divided into atopic and nonatopic categories on the basis of history of atopic respiratory disease and presence or absence of immediate (type-I) wheal-and-flare skin reactivity to a battery of commonly inhaled allergens, as previously described.f Subjects were not matched for age or sex. "Normal" nonatopic volunteers consisted of medical students and laboratory technicians. Atopic sera were obtained from allergy-clinic patients, either at the time of their initial visit or shortly thereafter. These patients had not received allergenic-extract immunotherapy. A total of 106 sera from the Milwaukee area, 117 from the New Orleans area, and 104 from the Denver

INCIDENCE OF SERUM PRECIPITINS 753



t('/IU~', and Asueruillu» [umiuutus were prepared from stock cultures Io(rowll in synthetic broth" for IS days. Fungi were harvested, defatted, wound , extracted, dialyzed , and lyophilized as previously de scr ibed." The basidiumycete, Puccinia co ro /lIl t a, was obtained from a commercial suppliert followinu clirect harve-st hom th e plant without defutting. The fungal Io(rowth was dried at room temperature for six days ami nu -chanicallv sil'H ,d with a 200-nll'sh sie ve . The dried, sieved sport's wen - extracted , dialyzed , and lyophilized as described earlier. The hasicliomycet«, Cantharellus ciharius (ATCC Xo . I:l22H) , was grown for IS days in Czapek-Dox broth (Difco l . Th« mycelial mat was washed in dt'ionized water, hlended in a hll 'ndcr (\\'aring) , homogenized in a cell homogenizer (Braun ) for three minutes using 0..1.'5 to 0 ..50 nun glass lx-ads , ami lyophil ized . Crude lyophilized somatic antigen was then exrrucn-d w ith O.lH ~I ~aCI at 4°C using a glass-rod rotator." \\'holl' giant- rag wt'ed pollen IAlllhrosia Irifida L I ohtuined from a c-omnu-rcial supplier: \\'as defatted with e ther five times ;\IId extracte-d for 24 hours at p l I 7 .3 with deionized water I : 10 (\\'l'ight /\'(lhune) , followed hy Mill ipore filtration and lyoph ilization.

Normal

~ Atopic

60

o

Wisconsin

Louisiana

Colorado

Population surveyed 1. Incidence of precipirins against house dust in sera from nonatopic and atopic residents of Wisconsin, Louisiana, and Colorado by counterirnmunoelectrophoresis. F(( ;VIIE

area were studied. Sera were freshly frozen at -20°C without preservation and th awed immediately prior to analysis. The techn ique of counterimmunoelectrophoresis was used to detcrmuu- th e presence of preeipitins to a variety of organic du st , fungal, ami actinomycetic antigens.

Antigl'n\ I lou se-dust antigen wa s obtained commercially 00 a nd extraetccl l : 10 (weiuhr /volume ) with Co ca's solution (SO.O Io(m of ~aCl , SS.O gm of ;\aHCO:1. and 45.0 ml of phenol 188 percent] II .S. 10.0 L distilled H ~O). After extraction th e supernatant was dialyzed against deionized water overnight ami lyoph ilized. " Soma tic" antigen of the th ermophilic uc-tuuuuvcc-te- . M icrol'o/ysl'ora [aeni , was prepared and homogenized with gla ss heads using a cell homogenizer ( Braun) as previously descrihed.:\·!i Crude fungal antigens of Candida albicans, A/temarkJ 00

C ou nteri 11I11Iu noclcc! rophorcsi» Counterimmunol'11'drophoresis was performed using lantern slides ( Kod a k) coated with 1.5.0 ml of O.H2-perct'nt Ionagar Xo, 2* in veronal huller, Lyophilized fungal and organic-dust antiuens (20.0 mg /ml ) \\ , 'f(' fre shly dissolved in verona I buller for on e hour prior to use . Three columns of 15 wells per plate were cut as previously described." Antigens were placed in cathodal wells (7 .O/-, I or 140/-,1o( absolute antigen co ncentrution l. and undiluted serum samples were placed in a nodal wells. Chromatographic-ally Fractionated serum samples precipitated with ammonium sulfate a nd used for innnunoglobul in specificity stud ics were d ialyzed against deionized water . lyophil ized , and reconstituted in verona] huller ( p i I H.2 ). Electrophoresis was ca rried out for (i0 min utes at constant voltage ( 5 .4 v per linear centimeter of agar and 20 ma per plat« ). Precipit in hands were idt'utified immediately after eh-ctrophoresis and fo!lo\\'inlo( \\'ash ing for 4H hours. drying, and stainim; with light Io(rt'en.:\ Diethylamino- -- - -

-

-

----

+Lot S 8-(;L. Cret' r La boratories. Lenoir, :\C. :Cret'r Laboratories. Lenoi r. ~c. *Colah Laboratoru-s. Gl euwrx«]. III. 30

Lot D-H-Hfi :1(; 10. G reer Laboratories, Lenoir, I\:C.

1

Optical 20 Dens;ty 01 280 mil

t

\

10

FraclionNo

2. Typical appearance of antidust precipitins followinlo( counterimmunoelectrophoresis, prior to washing and staining . F(( ;UIIE

754 PHANUPHAK ET Al

(precipitin act ivity) -

30 35 40 45 50 55 60 G5 70 75 00 859095 -

-

-

-

+ ++ +

-

FI< ; UIIE :1. Localizat ion of serum precipitins against house dust h y 10(1,1 filtration (Sephadt'x C-200 ).

CHEST, 68: 6, DECEMBER, 1975

100-

I

nonatopic atopic W Wisconsin L Louisiana C Colorado

o

80-

o

WLC Puccinia

coronata

I

.n I --WLC ---- .nWLC .n .n

WLC

Alternaria Aspergillus Cantharellus

tenuis

fumigatus

cibarius

Population surveyed and somatic antigen employed FIGURE 4. Incidence of antifungal serum precipitins in atopic and nonatopic sera from Wisconsin, Louisiana, and Colorado populations by counterimnlunoelectrophoresis.

ethyl-cellulose chromatography, gel filtration (Sephadex G200 ), ammonium-sulfate precipitation, and specific absorption studies with organic-dust antigens and x-acetylglucosamine were performed as previously described.f A sample of pooled sera, all of which illustrated weakly positive anticandida-precipitin band formation by counterimmunoelectrophoresis only after washing and staining, was employed for pepsin digestion. An I~G-rich fraction was recovered by precipitation with ammonium sulfate and recycling through gel filtration (Sephadex G-200) with horate buffer (pI-I 8.2) as eluting fluid. The IgC preparation recovered by gel filtration (Sephadex G-200) was dialyzed, lyophilized, and digested with pepsin as previously described. ~ After digestion the F ( ab' ):! fraction was concentrated and dialyzed against 0.1 M acetate buffer (pH 4.5), followed by lyophilization, and reconstituted in veronal buffer ( 15 mg/ml ) for counterimmunoelectrophoresis, RESULTS

The incidence of precipitins against house dust in the surveyed populations is illustrated in Figure 1, and their typical appearance following counter-

immunoelectrophoresis is shown in Figure 2. Antidust precipitins were detected with similar frequency in the atopic and nonatopic subjects of each geographic area. Seventy-one percent of normal sera and 66 percent of sera from atopic Wisconsin subjects demonstrated positive antidust-precipitin reactions. For Louisiana, 68 percent of normal sera and 48 percent of sera from atopic subjects were positive for antidust precipitins; and for Colorado, 71 percent of normal and 59 percent of atopic sera were positive. Group differences were not statistically significant for various geographic areas when the total numbers of positive precipitin reactions were compared per group, or per atopic and normal subgroups (P 2 0.05 for all group comparisons). Precipitin reactions were generally intense and easily visible prior to washing and staining. Multiple precipitin bands were detected with many sera, in keeping with the marked heterogeneity of the crude house-dust antigen employed. House-dust precipitins were present in serum fractions precipitated with ammonium sulfate and in IgG-rich fractions obtained by both gel filtration (Sephadex G-2(0) (Fig 3) and diethylaminoethyl-cellulose chromatography. Antidust precipitins were also absorbable either in part or completely after repeated serum incubation with specific dust antigen. They were not absorbed, however, by N-acetylglucosamine. The incidence of serum precipitins against Ai tenuis and As [umigatus was very low when compared with the high incidence of antidust precipitins ( Fig 4 ). Al tenuis precipitins were present in higher frequency in sera from atopic Wisconsin and Colorado subjects (17 percent and 18 percent, respectively, as opposed to 6 percent and 8 percent for nonatopic subjects). As [umigatus precipitins were not detectable with the antigen employed. In contrast to these findings, precipitins against the basidiospore, P coronate (grass smut), which had been harvested directly from the plant under unsterile conditions, were detected in 100 percent of all sera studied. Although present in serum fractions precipitated with ammonium sulfate, and IgG-rich fractions obtained by gel filtration (Sephadex G-2(0), these

A)

+ FIGURE 5. Tracing of arcs of precipitins against C and albicans following immunoelectrophoresis (A) and counterimmunoelectrophoresis (B) employing serum from patients with known mucocutaneous candidiasis (antigen concentration, 20.0 mgt ml ).

CHEST, 68: 6, DECEMBER, 1975

B)

o 01(

0

+

INCIDENCE OF SERUM PRECIPITINS 755



ESJ

M.F.

MF =M/cropo/ysporo faeni A T=Ambrosiotrif/do

Normal Atopic

AT

M.F

A.T. Louisiana

Wisconsin

M.F.

AT.

Colorado

Population surveyed fi. Incidence of antithermophilic actinomycetic (M [aeni) and giant-ragweed (Am trifida) precipitins in sera FI(;UHE

From atopic and nonatopic Wisconsin, Louisiana, and Colorado populations.

intense P coronata precipitin reactions did not diminish in intensity after ten absorptions with specific antigen or with N-acetylglucosamine. In the case of a second basidiospore antigen, Cant cibarius (A Tee No. 1322.3), which had been grown in Czapek-Dox broth, a very low incidence of precipitin detection was noted in all study groups. Thin, barely perceptible precipitin reactions to Cand albicans (not illustrated in Fig 4) were detected with unexpectedly high frequency in all groups (52 percent of nonatopic and 47 percent of atopic Wisconsin sera; 43 percent and 36 percent of Louisiana atopic and nonatopic sera, respectively, and 51 percent and 42 percent of Colorado atopic and nonatopic sera). These precipitin bands were faintly positive and were always observed only after washing and staining. They were not absorbable with Nacctylglucosamine but could be completely absorbed with specific antigen. Clear-cut anticandida precipitins present as prominent single or multiple bands on unstained slides were not noted in any subjects. After pepsin digestion of IgG from pooled sera illustrating weakly positive anticandida precipitin reactions, the F ( ab' ) 2 fraction did not give a positive precipitin band with Cand albicans antigen, indicating that these precipitins did not likely represent true antigen-antibody reactions. All such weakly counterimmunoelectrophoretic positive sera did not demonstrate precipitin arcs against Cand albicans antigen on either conventional Ouchterlony double-diffusion analysis or following immunoelectrophoresis. Conversely, serum samples from two positive control patients with known mucocutaneous candidiasis demonstrated intense multiple precipitin bands following counterimmunoelectrophoresis and immunoelectrophoresis (Fig 5). In these cases, anticandida precipitin activity was absorbable with

156 PHANUPHAK ET AL

specific antigen, present in ammonium-sulfate precipitates and in IgG-rich fractions obtained by gel filtration (Sephadex G-2(0), and not influenced by IgG pepsin digestion or by absorption with .Nacetylglucosamine. Figure 6 illustrates the degree of antithermophilic actinomycetic (M [aeni) and giant-ragweed (Am trifida) precipitins in different geographic populations. Antiragweed precipitins were not demonstrable in sera of atopic and nonatopic subjects, although from 12 percent to 17 percent of sera in all populations surveyed exhibited weakly positive precipitin reactions against M faeni. All sera exhibiting precipitins against M faeni by counterimmunoelectrophoresis were negative on conventional Ouchterlony double-diffusion analysis, suggesting that the technique of counterimmunoelectrophoresis was sufficiently sensitive to detect small amounts of precipitating antibody against this ubiquitous antigen in some members of the population at large. DISCUSSION

Our current results indicate that serum precipitins against organic dust are widespread in atopic and nonatopic populations of the southern, western, and north central United States. Precipitins against crude somatic fungal antigens were detected with considerably less frequency, and antiragweed precipitins were not detected in the populations surveyed. These results confirm and extend our previous finding of a high incidence of precipitins against organic dust in a southern US population." The current detection of such precipitins with similar frequency in diverse US populations indicates that our previously reported high precipitin incidence in residents of the New Orleans area was not due to excessive mold-spore and organic-dust antigenic stimulation associated with the peculiar semitropical environment, It would appear that prolonged environmental exposure to organic dusts and fungi in different geographic areas results in a similar "normal" serum precipitating-antibody response. This type of host response is compatible with the very low incidence of precipitins against fungal and pollen antigens, which likely provide only seasonal exposure of a lesser magnitude. Sensitivity of the procedure employed is also an important factor in comparing the incidence of antidust and antifungal antibodies detected by counterimmunoelectrophoresis with that of other investigators using different methods. While counterimmunoelectrophoresis is less sensitive than primary binding methods, such as the Farr ammonium-sulfate technique, it offers greater sensitivity than conventional Ouchterlony double diffu-

CHEST, 68: 6, DECEMBER, 1975

sion" and is likely of sufficient sensitivity to detect antidust antibody in the population at large. In this regard, it is of interest that the widespread detection of antibodies against culture filtrate and somatic antigens of common fungal and mycobacterial species, including As [umigatus and Mycobacterium tuberculosis, is being reported using primary binding procedures.P'P The universal presence of such antibodies, their increasing incidence of detection with age, and their established cross-reactivity with other fungi ~ and dusts 10-12 are all in keeping with the concept of a normal host response to ubiquitous environmental antigens commonly present in the atmosphere, soils, and organic dusts. Although the biologic significance of antidust precipitins is unknown and the antigens employed in our studies are grossly impure, the detection of precipitins in the normal population by counterimmunoelectrophoresis confirms previous observations that the presence of precipitins per se indicates only prior exposure to antigen, rather than diagnostic evidence of pulmonary hypersensitivity disease. The widespread presence and unknown biologic role of antidust serum precipitins also illustrate the need for functional characterization of these precipitins and for the use of more purified antigens in serologic diagnosis of the hypersensitivity pneumonitides. With regard to the specificity of the serum precipitins detected by counterimmunoelectrophoresis, false-positive reactions have been encountered in employing the technique to detect Australia antigen and anti-DNA antibody. 13,14 Reproducibility in different laboratories has also not been equivalent to that noted with conventional Ouchterlony double diffusion with M faeni antigen when commercial counterimmunoelectrophoretic kits incorporating Agarose agar and filter-paper wicks were employed;" Our current and previous results suggest, however, that most counterimmunoelectrophoretic precipitins against dust and fungal antigens are immunologically specific. This is evidenced by their absorption with a goat antihuman IgG immunosorbent," their detection in 33-percent ammonium-sulfate precipitated serum fractions, and their presence in IgG-rich diethylaminoethyl-cellulose" and Sephadex G-200 column fractions. Other possible false-positive reactions due to ,B-teichoic acids of Staphylococcus aureus or to C-substance anti-C-reactive protein reactions would also seem unlikely in view of our failure to absorb antidust precipitins with anti-C-reactive protein serum or with N-acetylglucosamine, a major determinant in teichoic acid." It is also unlikely that antidust precipitins might have failed to be detected by counterimmunoelectrophoresis due to the use of positively

CHEST, 68: 6, DECEMBER, 1975

charged antigens with cathodal mobility, since the antigens employed in our survey were primarily negatively charged, as evidenced by prominent anodal mobility on gel electrophoresis. There were, however, some possible false-positive or nonimmunologic precipitin reactions in our current survey, such as the strong and uniformly positive precipitin reactions detected against the basidiospore, P eoronata (grass smut). Although basidiospores appear to be highly antigenic in man and other species and they have been isolated in large numbers from the atmosphere.v'? we feel that our P eoronata spores, which had been harvested directly from the plant under unsterile conditions, were likely contaminated with bacterial and related antigens and, in effect, constituted a potent organicdust rather than specific basidiospore antigen. The fact that little precipitin activity was detected against a second basidiospore antigen (Cant eibarius) grown in Czapex-Dox broth under sterile conditions is also in keeping with this concept. As in the case of P eoronata precipitins, our de tee,tion of weakly positive bands against Cand albicans only after washing and staining also cannot be adequately explained at this time. Although absorbable with Cand albicans antigen and present in IgG-rich fractions obtained by gel filtration (Sephadex G-200), these weakly positive precipitin bands were not detected with the use of F( ab')2 fraction following pepsin digestion, strongly suggesting that the bands were nonimmunologic in nature. The well-defined multiple precipitin bands obtained after both counterimmunoelectrophoresis and conventional immunoelectrophoresis of sera from subjects with mucocutaneous candidiasis were, however, never observed in the atopic and nonatopic survey populations and most likely represent true antigen-antibody interactions. Our markedly variable incidence of precipitin detection using different crude fungal antigen preparations plus the presence of some likely false-positive reactions indicate the need for purification, characterization, and standardization of organic-dust and fungal antigens in order to obtain meaningful comparative results in future population surveys of this type and in disease diagnosis. REFERENCES

1 Pepys J: Monographs in Allergy: Hypersensitivity Diseases of the Lungs Due to Fungi and Organic Dusts (vol 4). Basel, Switzerland, S Karger AG, 1969 2 van Lookeran JG, Knoll K, deVries K: House dust provocation with children. Scand J Respir Dis 50:76, 1969 3 Kawai T, Salvaggio J, Arquembourg P, et al: Precipitating antibodies against organic dust antigens in human sera by counterimmunoelectrophoresis. Chest 64: 420-426, 1973

INCIDENCE OF SERUM PRECIPITINS 757

4 Salvaggio J, Seabury J: New Orleans asthma: 4. Semiquantitative airborne spore sampling, 1967 and 1968. J Allergy Clin ImmunoI48:32, 1971 5 Seabury J, Salvaggio J, Domer J, et al: Characterization of thermophilic actinomycetes isolated from residential heating and humidification systems. J Allergy Clin Immunol51: 161, 1973 6 Kimura P, Lopez M, Salvaggio J: Characterization of types of enzymatic activity in somatic extracts of selected Fungi, thermophilic actinomycetes and pollen by immunoelectrophoresis. Clin Allergy 4:405-412, 1974 7 Biguet J, Tran Van Ky P, Andrieu S, et a1: Analyse immunoelectrophoretique d'extraits cellulaires et de milieux de culture d' Aspergillus [umigatus par des immunoserum experimentaux et des serums de malades atteints d'aspergillome bronchopulmonaire. Ann Inst Pasteur 107 :72, 1964 8 Leslie C, Benedict A: Structural and antigenic relationships between avain immunoglobulins: 2. Properties of papain-and-pepsm-digested chicken, pheasant and quail IgC-immunoglobulins. J Immunol 104:810, 1970 9 Gocke 0, Howe C: Rapid detection of Australia antigen by counterimmunoelectrophoresis. J Immunol 104: 1031, IB70 10 Bardana EJ, McClatchy JK, Farr RS, et al: The primary

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interaction of antibody to components of aspergilli: 2. Antibodies in sera from normal persons and patients with aspergillosis. J Allergy Clin Immunol 50:222, 1972 Bardana EJ, ~fcClatchey JK, Farr RS, et al: Universal occurrence of antibodies to tubercle bacille in sera from non-tuberculous and tuberculous individuals. Clin Exp ImmunoI13:65, 1973 Bardana EJ: Conference on puhnonary reactions to organic materials: Measurement of humoral antibodies to aspergilli. Ann NY Acad Sci 221: 64, 1974 Prince A, Burke K: Serum hepatitis antigen (SH): Rapid detection by high voltage immunoelectrophoresis. Science 169:593, 1970 Arquembourg P, Lopez M, Biundo J, et a1: Detection of DNA antibody by counterimmunoelectrophoresis (CIE). Immunol Methods 5:199, 1974

15 Flaherty 0, Barboriak J, Emanuel 0, et al: Multilaboratory comparison of three immunodiffusion methods used for the detection of precipitating antibodies in hypersensitivity pneumonitis. J Lab Clin Med 84:298, 1974 16 Faux J, Holford-Strevens V, Wells ID, et a1: Teichoic acid false positive reaction. Clin Exp Immunol 7: 897, 1970 17 Gregory PH, Hirst JM: Possible role of basidiospores as airborne allergens. Nature 170:414, 1972

Rebellious Passion Portrayed in Classical Music At the end of the nineteenth century, Cesar Franck ( 1822-1890) became a Myth which modestly parallels the Wagnerian legend. The music what d'Indy dignified as Franck's First Period was written between 1841 and 1858. A decisive turning point comes in the Piano Quintet of 1879, in which for the first time we have a direct expression of the Franckian ego. Weare not surprised that Mme Franck loathed it ("Cesar, I do not approve of that music you are playing"); that the respectable Saint-Saens refused to play it in public; nor even that it brought a blush to the cheek of so experienced a sensualist as Franz Liszt. Whether or not it was composed in the heat of a (suppressed?) passion for Franck's pupil, Augusta Holmes, it sums up the essential Franckian theme: eroticism curbed, or rebellious passion

758 PHANUPHAK ET AL

that struggles to break free. Franck's most typical melody-oscillating chromatically around a single note, or see-sawing between the tonic and the mediant-embodies precisely this desire to escape from fixation: as does the extreme chromaticism of the harmony, as contrasted with the metrical rigidity of the four-bar periods. Franck derived his "motivic" conception and his piano technique from Liszt; his harmonic polyphony from Wagner; his philosophic solemnity from Beethoven; his interest in counterpoint and to some extent his chromaticism from Bach. Yet Franck's contemporaries were justified in thinking him a profoundly original force. Hannan, A, Milner, A and Mellers, W: Man and His Music-The Story of Musical Experience in the West, New York, Oxford U Press, 1962

CHEST, 68: 6, DECEMBER, 1975

Incidence of serum precipitins against organic-dust antigens in different populations by counterimmunoelectrophoresis.

The incidence of serum antidust and antifungal precipitins was determined by counterimmunoelectrophoresis in 317 atopic and nonatopic subjects of thre...
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