Idiotypic/antiidiotypic interactions in systemic lupus erythematosus: demonstration of oscillating levels of anti-DNA autoantibodies and reciprocal antiidiotypic activity in a single patient.

This work was designed to investigate the occurrence and evolution of autoantiidiotypic antibodies to double-stranded DNA in systemic lupus erythematosus (SLE). Serum samples from a patient with SLE who was submitted to repeated therapeutic plasmapheresis for 57 weeks were examined for the presence of autoantiidiotypic antibodies to DNA. Anti-DNA antibodies were affinity-purified from a serum sample obtained at the beginning of the observation period. Anti-anti-DNA activity, directed toward structures within the binding site of anti-DNA autoantibodies but not antibodies of another specificity, was detected in the serum of the patient. In addition, the decrease in the levels of anti-DNA antibodies took place concomitantly with a reciprocal increase in the autologous anti-idiotype. These results indicate that anti-DNA and anti-anti-DNA antibodies coexist in the serum of this patient, and suggest that antiidiotypic interactions may play a role in the modulation of idiotypic expression in SLE.