Hereditary C2 Deficiency Associated with Common Variable Immunodeficiency MAXIME SELIGMANN, M.D.; JEAN-CLAUDE BROUET, M.D.; and MARYLINE SASPORTES, M.D.; Paris, France
Homozygous C2 deficiency in a 19-year-old boy was associated with variable immunodeficiency manifested by marked hypoimmunoglobulinemia and impaired antibody responses, normal circulating B lymphocytes, and subnormal T-cell functions. Neither antilymphocytic autoantibodies nor chromosomal abnormalities were found. Serum immunoglobulin levels were within normal limits in his parents and brother who were heterozygous for C2 deficiency. The patient's lymphocytes were homozygous at the HLA-D locus but expressed an antigen different from DW2. ALTHOUGH
NEARLY
HALF OF T H E PATIENTS
with
ho-
m o z y g o u s deficiency o f the s e c o n d c o m p o n e n t o f c o m p l e m e n t are a s y m p t o m a t i c , this condition is frequently associated w i t h a u t o i m m u n e disorders, t h e c o m m o n e s t o f w h i c h is systemic lupus e r y t h e m a t o s u s (1). W e h a v e recently studied a b o y w i t h hereditary C 2 deficiency a n d i m m u n o g l o b u l i n deficiency, a hitherto u n r e c o g n i z e d association. W e report t h e clinical a n d laboratory investigations d o n e in this patient (proband) a n d his family. Case Report The patient was referred in 1977 for the evaluation of an immunodeficiency syndrome. This 19-year-old boy was born after an uneventful pregnancy and delivery. Common viral diseases and usual vaccinations gave no adverse reactions. However, since early childhood he experienced numerous bacterial upperrespiratory-tract infections, which led to adenoidectomy and tonsillectomy at the age of 2 years without relief of the symptoms. At the age of 6 months he was treated for a bacterial meningitis, and since the age of eight he had bacterial pneumonitis six times and often had chronic sinusitis and bronchitis. Hypogammaglobulinemia was discovered when he was 14 years old. Clinical examination results were normal except for slight mental retardation. The serum immunoglobulin levels evaluated by radial immunodiffusion were 3 g / L for IgG, 0.3 g / L for IgM, and 0.2 g / L for IgA. The study of the IgG subclasses and Gm allotypes did not show any evidence of a selective deficiency of a given IgG subclass. Allohemagglutinin titers were very low, as well as those of various antibodies against common pathogens. The absolute number of circulating lymphocytes was normal. The percentage of lymphocytes bearing complement receptors (EAC-rosettes) was 19%. The study of surface immunoglobulin-bearing lymphocytes by direct immunofluorescence with antisera to the various immunoglobulin chains showed normal figures for the various immunoglobulin isotypes Qi, 18%; 3, 17%; y, 1%; a, 0.5%; K, 17%; \ , 5%). The number of T lymphocytes was slightly depressed (50% of E rosetteforming lymphocytes, 900/mm 3 ). Intradermal reactions to tuberculin, candidin, and streptococcal antigens were negative, • From the Department of Immunopathology, Laboratory of Immunochemistry and Immunopathology, and Laboratory of Human Immunogenetics (Inserm Units 108 and 93, C N R S Laboratory of Oncology and Immunohematology, Research Institute on Blood Diseases of the University of Paris VII), Hopital SaintLouis; Paris, France. 216
Annals of Internal Medicine. 1979;91:216-217.
Downloaded from https://annals.org by Karolinska Institute user on 01/16/2019
but immunization with dinitrochlorobenzene was successful. In-vitro responses of the circulating lymphocytes to phytohemagglutinin, pokeweed mitogen, concanavalin A, and allogeneic cells (measured by 3H thymidine uptake) were within normal limits. Complement assays were done by Dr. A. Peltier according to the method of Mayer (2). The total hemolytic complement level and C2 hemolytic activity were undetectable. The levels of CI, C4, C3, C6, C7, and factor B measured by radial immunodiffusion or hemolytic assays, or both, were normal. Purified C2 restored normal total complement level. There were no detectable autoantibodies. Rheumatoid factors (as measured by the latex-fixation and Waaler-Rose tests) and antinuclear factors (assayed by immunofluorescence) were negative. Antibodies to lymphocytes were not found by cytotoxicity and immunofluorescence tests on normal circulating lymphocytes. The titer of the various antibodies to Epstein-Barr virus (against viral capsid antigen, early antigen, and nuclear antigen), measured by Dr. G. Lenoir, were low. The chemotactic activity of the patient's monocytes (studied by Dr. T. Pham) was normal, and his serum was able to generate chemotactic factors after adding purified C2. Chromosomal studies of stimulated circulating lymphocytes with banding techniques for G bands, R bands, and C bands showed a normal karyotype (done by Dr. R. Berger). A high degree of consanguinity was noted, because the parents of the patient were brother and sister (Figure 1). They were both heterozygous for C2 deficiency. One brother was also heterozygous, whereas the other brother had normal complement and C2 levels (Figure 1). Two siblings of the patient died in early infancy from unknown reasons. None of the living family members suffered from unusually frequent or severe infections. Their serum immunoglobulin levels were normal, with the exception of a slightly decreased level of IgA in the C2-deficient brother. Their serum was devoid of antinuclear antibodies. Typing for H L A done by lymphocytotoxicity (Dr. J. Hors in Prof. Dausset's laboratory) showed that the defective C2 gene was associated with the A10, B18, and A32, B8 haplotypes (Figure 1). The propositus was homozygous at the H L A - D locus as shown by the study of intrafamily mixed lymphocyte reactions. The patient's cells, when tested against homozygous D W 2 cells, gave a good response showing that they expressed a different and yet unidentified H L A - D locus. Comments Selective hereditary deficiency o f t h e s e c o n d c o m p o nent o f c o m p l e m e n t m a y lead t o severe bacterial infections ( 1 ) a n d is frequently associated w i t h various a u t o i m m u n e diseases a n d especially w i t h systemic l u p u s e r y t h e m a t o s u s ( 1 , 3-5) a n d w i t h anaphylactoid purpura (6) or chronic glomerulonephritis (7). O u r patient h a d n o n e o f these conditions, a n d presented w i t h a n a s y e t unreported association b e t w e e n C 2 deficiency a n d variable immunodeficiency w i t h p r e d o m i n a n t impairment o f h u m o r a l i m m u n i t y . T h a t t h e bacterial infections experie n c e d b y o u r patient were considerably i m p r o v e d after parenteral g a m m a g l o b u l i n therapy a n d were therefore
due to immunoglobulin deficiency is worth noting. Family studies in patients with homozygous C2 deficiency have shown a close linkage between the C2 gene and the H L A - D locus with a high disequilibrium in favor of the DW2 locus, which was found in eight of nine families reviewed by Agnello (1). The lymphocytes from our patient were homozygous at the H L A - D locus but expressed an alloantigen different from D W 2 and presently undetermined, similar to that of another patient who was previously studied by our group (5). With respect to the HLA-A and -B loci, the commonest antigens associated with C2 deficiency are A10 and B18 (1, 4). In the family we studied the proband was heterozygous because, in addition to A10, B18, he expressed the A32, B8 haplotype, which was present in his C2-heterozygous mother. Because the parents were siblings and the patient was homozygous at the HLA-D locus, a crossing over is likely to have occurred in the previous generation (which could not be studied). The most interesting finding in this case is the association with an immunodeficiency syndrome manifested by marked hypoimmunoglobulinemia and impairment of humoral immunity, normal circulating B lymphocytes, and subnormal T-cell functions. In the World Health Organization classification, this immunodeficiency would be labeled as "common variable with predominant immunoglobulin deficiency." This association raises some intriguing questions. Although the patient's bacterial infections began in early childhood, the clinical and immunologic data obtained in the propositus and his family do not allow us to conclude there is a genetic primary immunodeficiency. The hypothesis that the homozygous C2 deficiency is somehow responsible for the immune defect would be most appealing. Because autoimmune disorders are frequent in C2 deficiency, and because autoantibodies to B lymphocytes can play a role in the pathogenesis of immunoglobulin deficiencies (8), we looked carefully for such antibodies in our patient. The results were negative as could be anticipated in view of the normal number of circulating B lymphocytes. We also found no serologic evidence for an Epstein-Barr virus infection that may be responsible for the occurence of immunoglobulin deficiencies in genetically predisposed persons (9). Other possible links between the two defects detected in our patient could involve monocytic dysfunction or an abnormality of the sixth chromosome that was not shown by the cytogenetic study. A mere coincidence can of course not be
Figure 1 . HLA genotypes and C2 levels in the proband and his family members.
ruled out and, in view of the high degree of consanguinity, the patient could have inherited two unlinked abnormal genes. However, that Agnello (1) alluded to the finding in another patient with C2 deficiency of an isolated IgGl subclass deficiency is worth noting. • Requests for reprints should be addressed to Maxime Seligmann, M.D.; Laboratory of Immunochemistry, Batiment Inserm, Hopital Saint-Louis; 2, Place du Docteur Fournier; 75475 Paris Cedex 10, France. Received 29 December 1978; revision accepted 2 May 1979.
References 1. A G N E L L O V. Complement deficiency states. Medicine (Baltimore). 1978;57:1-23. 2. K A B A T EA, M A Y E R MM. Experimental Immunochemistry. 2 ed. Springfield, Illinois: Charles C Thomas; 1961 3. POLLEY MJ, BEARN AG. Genetic aspects of diseases of complement: an explosion. Am J Med. 1975;58:105-11. 4. SCHUR PH. Complement in lupus. In: Clinics of Rheumatic Diseases. London: W. B. Saunders; 1975:519-43. 5. B R O U E T JC, F R I D M A N W H , C L A U V E L JP, SASPORTES M, D A N O N F,
SELIGMANN M. Deficit genetique de la deuxieme fraction du complement avec manifestations lupiques: etude clinique et immunologique d'une nouvelle observation familiale. Nouv Presse Med. 1973;14:531-9. 6. SUSSMAN M, J O N E S JH, A L M E I D A J D , L A C H M A N N PJ. Deficiency of the
second component of complement associated with anaphylactoid purpura and presence of mycoplasma in the serum. Clin Exp Immunol. 1973;14:531-9. 7. K I M Y, F R I E N D PS, D R E S N E R IG, Y U N I S EJ, M I C H A E L A F . Inherited
deficiency of the second component of complement (C2) with membranoproliferative glomerulonephritis. Am J Med. 1977;62:765-71. 8. T U R S Z T, P R E U D ' H O M M E JL, L A B A U M E S, M A T U C H A N S K Y C, SELIG-
MANN M. Autoantibodies to B lymphocytes in a patient with hypoimmunoglobulinemia: characterization and pathogenic role. / Clin Invest. 1977;60:405-10. 9. PROVISOR AJ, I A C U O N E JJ, C H I L C O T E RR, N E I B U R G E R R G , CRUSSI
FG, B A E H N E R R. Acquired agammaglobulinemia after a life-threatening illness with clinical and laboratory features of infectious mononucleosis in three related male children. N Engl J Med. 1975;293:62-5.
Seligmann
Downloaded from https://annals.org by Karolinska Institute user on 01/16/2019
et al. • Hereditary C2 Deficiency
217
Homozygous C2 deficiency in a 19-year-old boy was associated with variable immunodeficiency manifested by marked hypoimmunoglobulinemia and impaired antibody responses, normal circulating B lymphocytes, and subnormal T-cell functions. Neither antilymphocytic autoantibodies nor chromosomal abnormalities were found. Serum immunoglobulin levels were within normal limits in his parents and brother who were heterozygous for C2 deficiency. The patient's lymphocytes were homozygous at the HLA-D locus but expressed an antigen different from DW2. ALTHOUGH
NEARLY
HALF OF T H E PATIENTS
with
ho-
m o z y g o u s deficiency o f the s e c o n d c o m p o n e n t o f c o m p l e m e n t are a s y m p t o m a t i c , this condition is frequently associated w i t h a u t o i m m u n e disorders, t h e c o m m o n e s t o f w h i c h is systemic lupus e r y t h e m a t o s u s (1). W e h a v e recently studied a b o y w i t h hereditary C 2 deficiency a n d i m m u n o g l o b u l i n deficiency, a hitherto u n r e c o g n i z e d association. W e report t h e clinical a n d laboratory investigations d o n e in this patient (proband) a n d his family. Case Report The patient was referred in 1977 for the evaluation of an immunodeficiency syndrome. This 19-year-old boy was born after an uneventful pregnancy and delivery. Common viral diseases and usual vaccinations gave no adverse reactions. However, since early childhood he experienced numerous bacterial upperrespiratory-tract infections, which led to adenoidectomy and tonsillectomy at the age of 2 years without relief of the symptoms. At the age of 6 months he was treated for a bacterial meningitis, and since the age of eight he had bacterial pneumonitis six times and often had chronic sinusitis and bronchitis. Hypogammaglobulinemia was discovered when he was 14 years old. Clinical examination results were normal except for slight mental retardation. The serum immunoglobulin levels evaluated by radial immunodiffusion were 3 g / L for IgG, 0.3 g / L for IgM, and 0.2 g / L for IgA. The study of the IgG subclasses and Gm allotypes did not show any evidence of a selective deficiency of a given IgG subclass. Allohemagglutinin titers were very low, as well as those of various antibodies against common pathogens. The absolute number of circulating lymphocytes was normal. The percentage of lymphocytes bearing complement receptors (EAC-rosettes) was 19%. The study of surface immunoglobulin-bearing lymphocytes by direct immunofluorescence with antisera to the various immunoglobulin chains showed normal figures for the various immunoglobulin isotypes Qi, 18%; 3, 17%; y, 1%; a, 0.5%; K, 17%; \ , 5%). The number of T lymphocytes was slightly depressed (50% of E rosetteforming lymphocytes, 900/mm 3 ). Intradermal reactions to tuberculin, candidin, and streptococcal antigens were negative, • From the Department of Immunopathology, Laboratory of Immunochemistry and Immunopathology, and Laboratory of Human Immunogenetics (Inserm Units 108 and 93, C N R S Laboratory of Oncology and Immunohematology, Research Institute on Blood Diseases of the University of Paris VII), Hopital SaintLouis; Paris, France. 216
Annals of Internal Medicine. 1979;91:216-217.
Downloaded from https://annals.org by Karolinska Institute user on 01/16/2019
but immunization with dinitrochlorobenzene was successful. In-vitro responses of the circulating lymphocytes to phytohemagglutinin, pokeweed mitogen, concanavalin A, and allogeneic cells (measured by 3H thymidine uptake) were within normal limits. Complement assays were done by Dr. A. Peltier according to the method of Mayer (2). The total hemolytic complement level and C2 hemolytic activity were undetectable. The levels of CI, C4, C3, C6, C7, and factor B measured by radial immunodiffusion or hemolytic assays, or both, were normal. Purified C2 restored normal total complement level. There were no detectable autoantibodies. Rheumatoid factors (as measured by the latex-fixation and Waaler-Rose tests) and antinuclear factors (assayed by immunofluorescence) were negative. Antibodies to lymphocytes were not found by cytotoxicity and immunofluorescence tests on normal circulating lymphocytes. The titer of the various antibodies to Epstein-Barr virus (against viral capsid antigen, early antigen, and nuclear antigen), measured by Dr. G. Lenoir, were low. The chemotactic activity of the patient's monocytes (studied by Dr. T. Pham) was normal, and his serum was able to generate chemotactic factors after adding purified C2. Chromosomal studies of stimulated circulating lymphocytes with banding techniques for G bands, R bands, and C bands showed a normal karyotype (done by Dr. R. Berger). A high degree of consanguinity was noted, because the parents of the patient were brother and sister (Figure 1). They were both heterozygous for C2 deficiency. One brother was also heterozygous, whereas the other brother had normal complement and C2 levels (Figure 1). Two siblings of the patient died in early infancy from unknown reasons. None of the living family members suffered from unusually frequent or severe infections. Their serum immunoglobulin levels were normal, with the exception of a slightly decreased level of IgA in the C2-deficient brother. Their serum was devoid of antinuclear antibodies. Typing for H L A done by lymphocytotoxicity (Dr. J. Hors in Prof. Dausset's laboratory) showed that the defective C2 gene was associated with the A10, B18, and A32, B8 haplotypes (Figure 1). The propositus was homozygous at the H L A - D locus as shown by the study of intrafamily mixed lymphocyte reactions. The patient's cells, when tested against homozygous D W 2 cells, gave a good response showing that they expressed a different and yet unidentified H L A - D locus. Comments Selective hereditary deficiency o f t h e s e c o n d c o m p o nent o f c o m p l e m e n t m a y lead t o severe bacterial infections ( 1 ) a n d is frequently associated w i t h various a u t o i m m u n e diseases a n d especially w i t h systemic l u p u s e r y t h e m a t o s u s ( 1 , 3-5) a n d w i t h anaphylactoid purpura (6) or chronic glomerulonephritis (7). O u r patient h a d n o n e o f these conditions, a n d presented w i t h a n a s y e t unreported association b e t w e e n C 2 deficiency a n d variable immunodeficiency w i t h p r e d o m i n a n t impairment o f h u m o r a l i m m u n i t y . T h a t t h e bacterial infections experie n c e d b y o u r patient were considerably i m p r o v e d after parenteral g a m m a g l o b u l i n therapy a n d were therefore
due to immunoglobulin deficiency is worth noting. Family studies in patients with homozygous C2 deficiency have shown a close linkage between the C2 gene and the H L A - D locus with a high disequilibrium in favor of the DW2 locus, which was found in eight of nine families reviewed by Agnello (1). The lymphocytes from our patient were homozygous at the H L A - D locus but expressed an alloantigen different from D W 2 and presently undetermined, similar to that of another patient who was previously studied by our group (5). With respect to the HLA-A and -B loci, the commonest antigens associated with C2 deficiency are A10 and B18 (1, 4). In the family we studied the proband was heterozygous because, in addition to A10, B18, he expressed the A32, B8 haplotype, which was present in his C2-heterozygous mother. Because the parents were siblings and the patient was homozygous at the HLA-D locus, a crossing over is likely to have occurred in the previous generation (which could not be studied). The most interesting finding in this case is the association with an immunodeficiency syndrome manifested by marked hypoimmunoglobulinemia and impairment of humoral immunity, normal circulating B lymphocytes, and subnormal T-cell functions. In the World Health Organization classification, this immunodeficiency would be labeled as "common variable with predominant immunoglobulin deficiency." This association raises some intriguing questions. Although the patient's bacterial infections began in early childhood, the clinical and immunologic data obtained in the propositus and his family do not allow us to conclude there is a genetic primary immunodeficiency. The hypothesis that the homozygous C2 deficiency is somehow responsible for the immune defect would be most appealing. Because autoimmune disorders are frequent in C2 deficiency, and because autoantibodies to B lymphocytes can play a role in the pathogenesis of immunoglobulin deficiencies (8), we looked carefully for such antibodies in our patient. The results were negative as could be anticipated in view of the normal number of circulating B lymphocytes. We also found no serologic evidence for an Epstein-Barr virus infection that may be responsible for the occurence of immunoglobulin deficiencies in genetically predisposed persons (9). Other possible links between the two defects detected in our patient could involve monocytic dysfunction or an abnormality of the sixth chromosome that was not shown by the cytogenetic study. A mere coincidence can of course not be
Figure 1 . HLA genotypes and C2 levels in the proband and his family members.
ruled out and, in view of the high degree of consanguinity, the patient could have inherited two unlinked abnormal genes. However, that Agnello (1) alluded to the finding in another patient with C2 deficiency of an isolated IgGl subclass deficiency is worth noting. • Requests for reprints should be addressed to Maxime Seligmann, M.D.; Laboratory of Immunochemistry, Batiment Inserm, Hopital Saint-Louis; 2, Place du Docteur Fournier; 75475 Paris Cedex 10, France. Received 29 December 1978; revision accepted 2 May 1979.
References 1. A G N E L L O V. Complement deficiency states. Medicine (Baltimore). 1978;57:1-23. 2. K A B A T EA, M A Y E R MM. Experimental Immunochemistry. 2 ed. Springfield, Illinois: Charles C Thomas; 1961 3. POLLEY MJ, BEARN AG. Genetic aspects of diseases of complement: an explosion. Am J Med. 1975;58:105-11. 4. SCHUR PH. Complement in lupus. In: Clinics of Rheumatic Diseases. London: W. B. Saunders; 1975:519-43. 5. B R O U E T JC, F R I D M A N W H , C L A U V E L JP, SASPORTES M, D A N O N F,
SELIGMANN M. Deficit genetique de la deuxieme fraction du complement avec manifestations lupiques: etude clinique et immunologique d'une nouvelle observation familiale. Nouv Presse Med. 1973;14:531-9. 6. SUSSMAN M, J O N E S JH, A L M E I D A J D , L A C H M A N N PJ. Deficiency of the
second component of complement associated with anaphylactoid purpura and presence of mycoplasma in the serum. Clin Exp Immunol. 1973;14:531-9. 7. K I M Y, F R I E N D PS, D R E S N E R IG, Y U N I S EJ, M I C H A E L A F . Inherited
deficiency of the second component of complement (C2) with membranoproliferative glomerulonephritis. Am J Med. 1977;62:765-71. 8. T U R S Z T, P R E U D ' H O M M E JL, L A B A U M E S, M A T U C H A N S K Y C, SELIG-
MANN M. Autoantibodies to B lymphocytes in a patient with hypoimmunoglobulinemia: characterization and pathogenic role. / Clin Invest. 1977;60:405-10. 9. PROVISOR AJ, I A C U O N E JJ, C H I L C O T E RR, N E I B U R G E R R G , CRUSSI
FG, B A E H N E R R. Acquired agammaglobulinemia after a life-threatening illness with clinical and laboratory features of infectious mononucleosis in three related male children. N Engl J Med. 1975;293:62-5.
Seligmann
Downloaded from https://annals.org by Karolinska Institute user on 01/16/2019
et al. • Hereditary C2 Deficiency
217
