title: Differences among immune complexes: association of C1q in SLE immune complexes with renal disease.
abstract: Studies that made use of multiple assay systems demonstrated increased levels of immune complexes (IC) in patients with systemic lupus erythematosus (SLE), but no consistent correlations of IC concentration to patterns or activity of disease have been observed. Furthermore, consistent associations between qualitative differences in IC and disease manifestations have been elusive. IC interaction with erythrocytes and mononuclear phagocytic cells is another variable in SLE that may also mediate some of the biological effects of IC. The present report concerns studies of the composition of purified IC obtained from individuals with SLE and other rheumatic diseases; a 64,000 dalton component identified as the A-B subunit of C1q was detected in purified IC from 27 of 51 SLE patients (53%). The presence of this 64,000 dalton component was not related to either IC concentration or to the serum C1q level. However, the presence of the C1q component in isolated SLE IC did correlate with the presence of renal disease (p less than 0.02). These observations are interpreted relative to a recently described kinetic model of IC clearance.
mesh_terms: D000936:Antigen-Antibody Complex / Q000032:analysis*; D003166:Complement Activating Enzymes / Q000032:analysis* / Q000276:immunology; D003172:Complement C1 / Q000032:analysis* / Q000276:immunology; D015922:Complement C1q; D003165:Complement System Proteins / Q000502:physiology; D005260:Female; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D007674:Kidney Diseases / Q000276:immunology*; D007700:Kinetics; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D008297:Male; D008657:Metabolic Clearance Rate; D008970:Molecular Weight
chemical_list: D000936:Antigen-Antibody Complex; D003172:Complement C1; D007106:Immune Sera; D015922:Complement C1q; D003165:Complement System Proteins; D003166:Complement Activating Enzymes