title: Correlation between anti-C1q and immune conglutinin levels, but not between levels of antibodies to the structurally related autoantigens C1q and type II collagen in SLE or RA.
abstract: The simultaneous appearance of autoantibodies with either a functional or structural relationship to anti-C1q antibodies (anti-C1q) was investigated in 39 systemic lupus erythematosus (SLE) patients and in 28 rheumatoid arthritis (RA) patients, in both cross-sectional and longitudinal design. Levels of anti-C1q showed an isotype-specific correlation to levels of immune con-glutinin (IK) in SLE patients, whereas no correlation was evident to levels of antibodies to the structurally related antigen type II collagen (anti-CII) in SLE or RA patients. IgG anti-C1q levels correlated with serum levels of the terminal complement complex (sC5b-9) in SLE patients. In two longi-tudinally followed patients, the IK response preceded the anti-C1q response. Possibilities for regulation of the humoral anti-complement response are discussed.
authors.affiliation: Department of Medicine, Rheumatology Unit, Karolinska Hospital, Stockholm, Sweden. Johan.Ronnelid@cmm.ki.se
authors.forename: J
authors.initials: J
authors.lastname: Rönnelid
authors.forename: I
authors.initials: I
authors.lastname: Gunnarsson
authors.forename: K
authors.initials: K
authors.lastname: Nilsson-Ekdahl
authors.forename: B
authors.initials: B
authors.lastname: Nilsson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood*; D001324:Autoantigens; D016022:Case-Control Studies; D003094:Collagen / Q000276:immunology; D015922:Complement C1q / Q000276:immunology*; D015938:Complement Membrane Attack Complex / Q000378:metabolism; D005260:Female; D006801:Humans; D037561:Immunoconglutinins; D007074:Immunoglobulin G / Q000097:blood; D007136:Immunoglobulins / Q000097:blood*; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D008297:Male; D008875:Middle Aged
chemical_list: D001323:Autoantibodies; D001324:Autoantigens; D015938:Complement Membrane Attack Complex; D037561:Immunoconglutinins; D007074:Immunoglobulin G; D007136:Immunoglobulins; D015922:Complement C1q; D003094:Collagen