Combined granulocyte and platelet transfusions. Development of alloimmunization as reflected by decreasing cell recovery values.

Twenty-three patients undergoing induction therapy for acute myelogenous leukemia (AML) received a total of 191 combined prophylactic granulocyte (PMN) and platelet (PLT) concentrates on alternate days (median 8, range 3-12 per patient). Each transfusion was assessed by monitoring the patient for reactions and by estimating the recovery of PMN in the circulation at 1 hour and of PLT at 1 and 20 hours. Seventeen patients developed alloimmunization to PLT from at least one donor, defined as either a PLT recovery of less than 15 percent at 1 hour and/or less than 10 percent at 20 hours. In this group there was a progressive reduction in PMN and PLT recovery with increasing transfusion number, strongly suggesting alloimmunization to both cells. Thirty-four transfusions were accompanied by transfusion reactions, thirty-two of which occurred in ten patients who had PMN recoveries of less than 5 percent after at least one transfusion (median 2.5, range 1-6 transfusions per patient). Actuarial calculations predicted that 70 percent of patients would become alloimmunized to PLT from at least two individuals after receiving 11 transfusions. These results suggest that combined PMN and PLT transfusion are associated with the rapid development of alloimmunization.