Rheumatoid Factors and Rheumatoid Arthritis

Rheumatoid factors (RFs) are autoantibodies which bind the Fc region of IgG (1, 2). They can be induced in experimental animals by B cell mitogens and by immunization with a variety of different antigens. Induction by the antigen-driven route has been accomplished only in secondary but not in primary immunization, suggesting that RFs arise as a response occasioned by antigenlantibody-complex rather than the antigen alone.