Protection of a Complement-Sensitive Enzyme System by Rheumatoid Factor

Summary 1.A factor in rheumatoid euglobulin can protect an enzyme-anti-enzyme system from the inhibitory effects of serum complement. 2.The enzyme-protection effect correlated with the γ-globulin-coated latex particle agglutination titer. 3.This factor could be adsorbed onto sensitized sheep cells and was presumed to be rheumatoid factor. 4.The factor blocks complement fixation, resulting in recovery of complement in the supernatant fluid in active form. There is no evidence for direct inactivation of complement by rheumatoid factor.