Abstract
Gamma globulin (7S) isolated by chromatographic techniques from 2 normal individuals and from 1 patient with rheumatoid arthritis coats tannic acid-treated sheep erythrocytes and detects rheumatoid factors with a specificity not found using pooled human gamma globulin. The serological specificity of individual gamma globulin preparations was destroyed by heating the protein to 63[degree]C for 5 minutes. The specificity was also observed in an inhibition system using whole rheumatoid serum or its pseudoglobulin fraction. The results may be due to the presence of multiple determinants in both the 7S gamma globulin isolated from individuals as well as in the rheumatoid factor complex found in individual rheumatoid sera.