Rheumatoid factor appearance in Micrococcus lysodeikticus immunization and its interference with allotype specific reactions.

Rabbits hyperimmunized with Micrococcus lysodeikticus produce, in addition to anti-cell wall antibodies, considerable amounts of anti-immunoglobulins or rheumatoid factors which can interfere with immune reactions. In particular, in immunodiffusion, they can reveal non precipitating systems for which the immunodiffusion typing sera are usually not tested. In our hands, rabbit allotypes d12 and A8 give rise to visible immunodiffusion reactions in presence of rheumatoid factors. Inhibition of this reaction can be used to type for these markers in sera which do not contain the rheumatoid factors.