Open AccessAntibodies to the collagen‐like region of C1q in sera of patients with autoimmune rheumatic diseases
Author(s) -
Wener Mark H.,
Uwatoko Shu,
Mannik Mart
Publication year - 1989
Publication title -
arthritis & rheumatism
Language(s) - English
Resource type - Journals
eISSN - 1529-0131
pISSN - 0004-3591
DOI - 10.1002/anr.1780320506
Subject(s) - antibody , rheumatoid arthritis , immunology , immune system , immune complex , antigen antibody complex , anti dsdna antibodies , medicine , lupus erythematosus , arthritis , autoantibody , chemistry
Antibodies to the collagen‐like region of C1q have recently been observed in sera of patients with systemic lupus erythematosus (SLE). In this study, we documented that these antibodies were present in 47.3% of SLE patient sera, whereas they were uncommon in sera from patients with rheumatoid arthritis (2.8%) and Sjögren's syndrome (12.8%), as well as in normal sera (6.4%). Markedly elevated antibody levels (>4 SD above the normal mean) were observed almost exclusively in sera of patients with SLE. Levels of antibodies to the collagen‐like region correlated highly with levels of solid‐phase C1q‐binding IgG when analyzed by the C1q solid‐phase assay for immune complexes (r = 0.87). We previously found that, after sucrose density gradient ultracentrifugation, a predominance of the solid‐phase C1q‐binding IgG in SLE sera sediments as monomeric IgG. These findings, together with the present data, indicate that reactivity of SLE patients' sera in the C1q solid‐phase assay reflects primarily the presence of antibodies to the collagen‐like region, and not the presence of immune complexes.