Anti-idiotypic antibodies to four monoclonal IgM, one polyclonal IgM, and one polyclonal IgA rheumatoid factors were produced in rabbits and tested for cross reactivity with rheumatoid factors from nine patients with essential mixed cryoglobulinaemia, three patients with rheumatoid arthritis, four patients with systemic sicca syndrome, and one patient with systemic lupus erythematosus. Variable...

Sera from nine patients with cryptococcal infections and from four with rheumatoid arthritis and positive rheumatoid factor were examined for the presence of cryptococcal capsular antigen by the latex agglutination method. Ethylenediaminetetraacetic acid-heat treatment of the sera before testing possibly increased sensitivity as compared with the untreated sera, and the interfering rheumatoid f...