LOW INCIDENCE OF SPECIFIC ANTIPLATETLET ANTIBODIES DETECTED BY THE MAIPA ASSAY IN THE SERUM OF THROMBOCYTOPENIC MDS PATIENTS AND LACK OF CORRELATION BETWEEN PLATELET AUTOANTIBODIES, PLATELET LIFE-SPAN AND RESPONSE TO DANAZOL THERAPY

We prospectively studied the mechanism of thrombocytopenia in 30 patie nts with myelodysplastic syndrome (MDS), who had a platelet count less than or equal to 70 x 10(9)/l, and marrow blasts less than or equal t o 10% by analysis of platelet lifespan, platelet-bound IgG antibodies by platelet radioactive antiglobulin test (PRAT), and circulating and platelet-bound autoantibodies specifically directed against platelet g lycoproteins by indirect and direct MAIPA test. PRAT analysis was posi tive in 21/30 patients (70%), but antiplatelet antibodies were found i n only eight by the MAIPA test, Platelet lifespan was shortened in fiv e cases, only one of whom had a positive MAIPA test, Patients were tre ated bg danazol (600 mg/d), and 9/26 evaluable patients (35%)responded , including three of the five patients with shortened platelet lifespa n. No correlation between platelet lifespan, results of PRAT and MAIPA tests, and response to danazol was found. In conclusion, specific ant iplatelet autoantibodies, reduced platelet lifespan, and efficacy of a ndrogen therapy on platelets were seen in 20%, 17% and 35% of MDS with thrombocytopenia, respectively, but no correlation between these find ings was found in this study.