Production and characterization of a human monoclonal anti-idiotype to anti-ribosomal P antibodies.

Autoantibodies to ribosomal P protein (anti-P) are a specific hallmark of systemic lupus erythematous (SLE). Several authors found significant associations of anti-P antibodies with neuropsychiatric, hepatic, and renal disease. We now report the isolation by phage display of human anti-idiotype (Id) monoclonal antibody fragments as single-chain Fv fragment (scFv) against anti-P antibodies. The V gene repertoires were derived from the RNA obtained from the B cells of a SLE patient. Affinity-purified anti-P antibodies were used for the selection of bacterial clones producing anti-P-specific scFv antibody fragments and little reactivity with normal IgG and other IgG antibodies. The anti-Id antibody recognizes a public idiotope broadly cross-reactive with polyclonal anti-P antibodies and inhibited binding of anti-P to ribosomal P antigen in immunoassays and on Jurkat cells. The anti-Id scFv antibody fragment may have therapeutic implications in SLE. They may also be used as probes in the study of the structure of the idiotype.