Leukocyte reduction and ultraviolet B irradiation of platelets to prevent alloimmunization and refractoriness to platelet transfusions.

BACKGROUND: We conducted a multi-institutional, randomized, blinded trial to determine whether the use of platelets from which leukocytes had been removed by a filter or that had been treated with ultraviolet B irradiation would prevent the formation of antiplatelet alloantibodies and refractoriness to platelet transfusions.

METHODS: Patients who were receiving induction chemotherapy for acute myeloid leukemia were randomly assigned to receive one of four types of platelets transfusions: unmodified, pooled platelet concentrates from random donors (control); filtered, pooled platelet concentrates from random donors (F-PC); ultraviolet B-irradiated, pooled platelet concentrates from random donors (UVB-PC); or filtered platelets obtained by apheresis from single random donors (F-AP). All patients received transfusions of filtered, leukocyte-reduced red cells.

RESULTS: Of 530 patients with no alloantibodies at base line, 13 percent of those in the control group produced lymphocytotoxic antibodies and their thrombocytopenia became refractory to platelet transfusions, as compared with 3 percent in the F-PC group, 5 percent in the UVB-PC group, and 4 percent in the F-AP group (P< or =0.03 for each treated group as compared with the controls; there were no significant differences among the treated groups). Lymphocytotoxic antibodies were found in 45 percent of the controls, as compared with 17 to 21 percent in the treated groups (P<0.001 for each treated group as compared with the controls; there were no significant differences among the treated groups). Antibodies against platelet glycoproteins developed in 6 to 11 percent of the patients, with no significant differences among the four groups.

CONCLUSIONS: Reduction of leukocytes by filtration and ultraviolet B irradiation of platelets are equally effective in preventing alloantibody-mediated refractoriness to platelets during chemotherapy for acute myeloid leukemia. Platelets obtained by apheresis from single random donors provided no additional benefit as compared with pooled platelet concentrates from random donors.