Immunologic thrombocytopenic purpura in human immunodeficiency virus--seropositive patients with hemophilia. Comparison with patients with classic autoimmune thrombocytopenic purpura, homosexuals with thrombocytopenia, and narcotic addicts with thrombocytopenia.

The immunologic platelet profile of 29 patients with hemophilia who had received multiple transfusions (14 had thrombocytopenia) was compared with profiles of 15 patients with classic autoimmune thrombocytopenia. Thrombocytopenic hemophiliacs who were seropositive for the human immunodeficiency virus (13 out of 14) had platelet-bound immunoglobulin G and C3C4 levels as well as circulating immune complexes that were 15.1-, 4.0-, and 2.4-fold greater, respectively, than normal control subjects' platelets and 3.4-, 2.6-, and 2.4-fold greater, respectively, than autoimmune thrombocytopenic patients' platelets. Hemophiliacs with normal platelet counts (nine out of 13 seropositive) had elevated values that were intermediate in level between those of thrombocytopenic hemophiliacs and those of classic autoimmune thrombocytopenic patients. The four seronegative hemophiliacs had normal values (except for one platelet-bound IgG measurement). An inverse correlation was noted between platelet count and platelet-bound IgG, r = -0.838, P less than 0.001. Serum antiplatelet reactivity (1:256 mean titer compared with control sera) resided predominantly in the 7S IgG fraction, and bound to autologous as well as homologous platelets at concentrations as low as 0.06 to 0.13 mg/ml. F(ab')2 fragments of the 7S IgG fraction inhibited binding of hemophilic IgG to normal platelets and bound to normal platelets at concentrations as low as 0.06 mg/ml. Antiplatelet IgG could be eluted from six of six hemophilic and eight of eight classic autoimmune thrombocytopenic patients.(ABSTRACT TRUNCATED AT 250 WORDS)