Gamma globulin complexes in synovial fluids of patients with rheumatoid arthritis. Partial characterization and relationship to lowered complement levels.

Gamma globulin complexes were demonstrable in certain joint fluids from patients with rheumatoid arthritis by analytic and density gradient centrifugation. They form a continuum of high molecular weight components ranging from 7S to 30S and were dissociable primarily to 7S γG globulin. The larger complexes were also detectable by precipitation reactions with C1q and with γM rheumatoid factor. This permitted the isolation and partial characterization of the complexes. Non-immunoglobulin constituents were not detectable. Evidence was obtained that 7S γG globulin rheumatoid factors represented an important constituent of the complexes. A relationship was encountered between the amount of γ globulin complex present in the joint fluids and diminution in total haemolytic complement activity. All fluids with abundant γ globulin complexes contained markedly lowered complement levels. A decrease in levels of C1q and β was found to correlate with the amount of γG globulin complexes. Although patients who had diminished complement levels in their joint fluid have serum γM rheumatoid factor, its titre does not correlate well with the extent of complement depression. Joint fluids with abundant γ globulin complexes manifested an anticomplementary effect. This activity was most apparent at 37°C when fresh rheumatoid serum was used as a source of complement. Evidence indicating the participation of γM rheumatoid factor in this anticomplementary effect was obtained. All fluids with significant anticomplementary activity formed precipitin bands with C1q on agarose plates. γM rheumatoid factor was not necessary for this reaction.