title: Isolation and characterization of circulating immune complexes in patients with rheumatoid arthritis.
abstract: We studied soluble immune complexes in sera and synovial fluids of ten patients suffering from Rheumatoid Arthritis (RA), six seropositive and four seronegative. Isolation of the immune complexes was obtained by a combination of gel filtration and affinity chromatography from biological fluids. The first step involved preparation of a globulin-enriched fraction by precipitation of either serum or synovial fluid with 5% polyethylene glycol 6000. The precipitate was solubilized in Borate NaCl buffer and fractioned by gel filtration in Ultrogel AcA 34. Eluted peaks were submitted to affinity chromatography on a Protein A-Sepharose CL 4B column. The recovered material was analyzed by double immunodiffusion and electrophoresis in 6-20% polyacrylamide gel containing sodium dodecylsulphate (SDS-PAGE) and was shown to contain IgG, IgM, IgA with small amounts of C1q, C3 and C4. Observation occurred that there is a different distribution of macromolecular and intermediate complexes in seropositive and seronegative samples respectively, total C1q binding activity being equal.
mesh_terms: D000936:Antigen-Antibody Complex / Q000302:isolation & purification*; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D003166:Complement Activating Enzymes / Q000032:analysis; D015922:Complement C1q; D003176:Complement C3 / Q000032:analysis; D003181:Complement C4 / Q000032:analysis; D006801:Humans; D007070:Immunoglobulin A / Q000032:analysis; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D013582:Synovial Fluid / Q000276:immunology
chemical_list: D000936:Antigen-Antibody Complex; D003176:Complement C3; D003181:Complement C4; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D015922:Complement C1q; D003166:Complement Activating Enzymes