Rheumatoid arthritis, rheumatoid factor, and tests for Australia or hepatitis-associated antigen

False-positive results in tests for hepatitis-associated antigen using latex agglutination techniques may be due to rheumatoid factor in the serum. Possibly the use of IgM antibody in preparing the latex particles might diminish the occurrence of such reactions. No evidence was found for a relation between rheumatoid arthritis and a significant incidence of hepatitis-associated antigen detectable by countercurrent immunoelectro-osmophoresis.