Autoimmunity and absence of rheumatoid factors in experimental Trypanosoma (Trypanozoon) equiperdum infections in the rabbit.

The serum levels of IgM and IgG have been shown to increase approximately 7 to 10 times during the development of Trupanosoma equiperdum infection in the rabbit. After separation of the 7 S and 19 S fractions by density gradient centrifugation, both fractions were found by complement fixation tests to contain anti-trypanosome antibodies. The 19 S fraction also contained autoantibodies reacting with tissue antigens of rabbit liver, kidney and heart. Results of passive haemagglutination and latex fixation tests could not confirm earlier reports of the presence of rheumatoid factors in infected rabbits.