Inclusion Criteria:  Donors who met criteria of Egyptian National Transfusion services Donors who had not taken any antiplatelet drugs for two weeks prior to donation pre-collection platelet count ≥200×109 /L. Blood grouping. Serological assays for all blood donors (HBsAgs, HCV antibodies, HIV Ag/Ab Syphilis antibodies) on Architect i 2000 SR or Centaur XPT (chemoluminescence).  Exclusion Criteria:  Donors who not met criteria of Egyptian National Transfusion services Donors who had taken any antiplatelet drugs for two weeks prior to donation pre-collection platelet count <200×109 /L. Reactive serology