A PROSPECTIVE, RANDOMIZED STUDY OF THE USE OF PLATELET CONCENTRATES IRRADIATED WITH ULTRAVIOLET-B LIGHT IN PATIENTS WITH HEMATOLOGIC MALIGNANCY

Background: Irradiation of platelet concentrates (PCs) with ultraviole t-B (UVB) light inactivates the contaminating white cells and might be an alternative to filtration for the prevention of alloimmunization t o HLA antigens and subsequent refractoriness to further platelet trans fusions in multiply transfused patients with bone marrow failure. Stud y Design and Methods: Patients with hematologic malignancy, mainly acu te myeloid leukemia, were prospectively assigned in a random manner to receive either UVB-irradiated or control, nonirradiated PCs. All pati ents were given red cells that were white cell reduced by filtration. Transfusion efficacy and alloimmunization were assessed by means of co rrected count increments, requirement for red cells and PCs, and measu rement of lymphocyte-reactive antibodies. Results: UVB-irradiated PCs had a clinical efficacy similar to controls as judged by corrected cou nt increments at 1 to 6 and 12 to 24 hours and by the median requireme nt for red cell and platelet transfusions. Alloimmunization determined by measurements of lymphocyte-reactive antibodies using both conventi onal and antiglobulin-augmented lymphocytotoxicity techniques was not abolished in recipients of UVB-irradiated PCs (4/30, 13%) but was less than that in controls (5/20, 25%; p = NS). The mean number of platele t transfusion episodes prior to the occurrence of alloimmunization was greater in the control group (27 vs. 10; p = 0.017). Conclusion: In t his trial, UVB irradiation did not diminish the clinical efficacy of p latelet transfusions. There was a small but nonsignificant reduction i n alloimmunization, but no difference in refractoriness of the two gro ups was observed. Larger prospective randomized studies are required t o confirm these findings and to compare UVB irradiation with white cel l reduction.