Leukocyte Depletion of Random Single-Donor Platelet Transfusions Does Not Prevent Secondary Human Leukocyte Antigen-Alloimmunization and Refractoriness: A Randomized Prospective Study

We studied the value of leukocyte depletion of platelet transfusions for the prevention of secondary human leukocyte antigen (HLA)-alloimmunization in patients with a high-risk of prior immunization induced by pregnancies. Seventy-five female patients with hematologic malignancies (mostly acute leukemia) and a history of pregnancy were randomized to receive either standard random single-donor platelet transfusions (mean leukocytes, 430 × 106 per transfusion) or leukocyte-depleted random single-donor platelet transfusions, Leukocyte depletion to less than 5 × 106 leukocytes per platelet transfusion (mean leukocytes, 2 × 106 per transfusion) was achieved by filtration. Of the 62 evaluable patients, refractoriness to random donor platelets occurred in 41% (14 of 34) of the patients in the standard group and in 29% (8 of 28) of the patients in the filtered group (P = .52); anti-HLA antibodies developed in 43% (9 of 21) of individuals in the standard group and 44% (11 of 25) of cases in the filtered group. The time toward refractoriness and development of anti-HLA antibodies was similar for both groups. We conclude that leukocyte depletion of random single-donor platelet products to less than 5 × 106 per transfusion does not reduce the incidence of refractoriness to random donor platelet transfusions because of boostering of anti-HLA antibodies.