Immunological properties of isolated IgG and IgM anti-gamma-globulins (rheumatoid factors)

Abstract

Anti-gamma-globulins of the IgG and IgM classes have been isolated from sera of normal individuals and from patients with osteoarthritis, rheumatoid arthritis and juvenile rheumatoid arthritis. AH of the isolated antibodies gave precipitin curves with heat-aggregated, reduced and alkylated gamma-globulin. IgM antigamma-globulins gave a positive latex fixation test at 4 °C and 37°C while IgG antigamma-globulins generally gave a positive test only a t 4°C. Anti-gamma-globulins from normals did not fix complement but IgG and IgM anti-gamma-globulins from rheumatoids fixed complement to a similar degree. This in vitro complement fixation could account at least in part for the diminished complement levels seen in many rheumatoid synovial effusions.