ANTI-HLA AND ANTI PLATELET ANTIBODIES IN BLOOD RECIPIENTS ARE PRODUCED DURING ALLOIMMUNIZATION, BUT IN SOME RECIPIENTS CONTINUE TO GRADUALLY DISAPPEAR, THAT SHOWING SUPPRESSION OF THE IMMUNE RESPONSE DUE TO transfusion RELATED IMMUNOMODULATION. IN THIS STUDY ANTIBODIES AGAINST HLA-I AND PLATELET ANTIGENS WERE DETECTED BY FLOWCYTOMETRY, IN 33 PATIENTS WITH AML (CANDIDATE FOR HSCT) AND 24 PATIENTS WITH ITP. THE PATIENTS WERE TRANSFUSED BY PACKED RED CELLS AND PLATELET CONCENTRATES.