MODULATION OF IDIOTYPIC AND ANTIIDIOTYPIC IMMUNOGLOBULIN-G RESPONSES IN AN IMMUNE THROMBOCYTOPENIC PURPURA PATIENT AS A CONSEQUENCE OF EXTRACORPOREAL PROTEIN-A IMMUNOADSORPTION

Immune thrombocytopenic purpura (ITP) is an autoimmune disorder charac terized by the presence of antiplatelet antibody which sensitizes plat elets resulting in their clearance by the reticuloendothelial system. Extracorporeal protein A immunoadsorption has been demonstrated to be of benefit in the treatment of this autoimmune disorder. In the presen t study, a patient with underlying systemic lupus erythematosus (SLE) presented with ITP. The patient received 14 immunoadsorption treatment s and responded to therapy. During the course of immunoadsorption trea tments, there was a decline in circulating immune complex (CIC) levels , antinuclear antibody (ANA) levels, and antiplatelet IgG antibody lev els. In addition, elevated levels of antiidiotypic IgG antibody detect ed before initiation of therapy were significantly reduced during the course of immunoadsorption treatments. This study suggests that specif ic autoimmune idiotypic IgG antibody and corresponding antiidiotypic I gG antibody responses may be modulated in association with extracorpor eal immunoadsorption employing protein A/silica columns.