Mycoplasma antibodies in rheumatoid arthritis.

Sera of 100 patients under examination at the Outpatient Department of the Rheumatism Foundation Hospital were studied by the indirect hemagglutination technique, using both mycoplasma reference strains, and isolates from RA and SLE as antigens. The series consisted of five groups: I, definite RA (49 patients); II, probable RA (11); III, possible RA or nonspecific inflammatory arthritis (34); IV, osteoarthrosis (2); V, Reiter's disease (4). Mycoplasma antibodies in titres of 16 or higher were encountered in groups I-IV in 26, 8, 19, and one case respectively. Twenty-one out of 106 blood donors had antibodies against an isolate from RA and/or M. arthritidis strain PG 6. The titres found were 16 or 32, except in two cases, 128. In the definite RA group, 21 out of 26 patients possessing mycoplasma antibodies, showed titres of 16 or higher against isolates from RA and/or SLE, 12 against M. arthritidis strain PG 6 and/or Campo, 8 against M. fermentans, and 6 against a T-strain from NGU. Antibodies against M. arthritidis strain Campo were found more often than against strain PG 6. The longer the duration of the arthritic symptoms was, the more frequent seemed also to be the occurrence of mycoplasma antibodies.