MANAGEMENT OF PATIENTS WITH HEMATOLOGIC MALIGNANCIES AND APLASTIC-ANEMIA WHO ARE REFRACTORY TO PLATELET TRANSFUSIONS

Patients with hematologic malignancies or aplastic anemia may have red uced responses to platelet transfusions after multiple transfusions of standard red blood cells or platelet components. This situation, conv entionally described as 'refractoriness' to platelet transfusions, may result from immune or non-immune causes. Non-immune causes include fe ver, infections, hypersplenism, disseminated intravascular coagulation , antibiotics, or veno-oclusive disease. Immune causes include platele t-reactive alloantibodies, which are typically antibodies to human leu kocyte antigens (HLA) or, less commonly, antibodies to human platelet antigens (HPA). Transfused HLA-matched platelets often have satisfacto ry posttransfusion survivals, but few transfusion services have the do nor and logistical resources to sustain a prolonged course of platelet transfusions requiring four-antigen matches. The availability of comm ercially marketed kits for crossmatching samples of potential donors' platelets with a recipient's serum has facilitated donor-recipient mat ching. Also, platelet crossmatching may be used to select a suitable u nit of from several candidates platelets that have been identified to be partial HLA matches. The high likelihood of decreased efficacy of p latelet transfusions in HLA-alloimmunized recipients makes avoidance o f exposure to HLA-bearing leukocytes a priority. This goal is facilita ted by lowering transfusion 'triggers' for cellular blood components, particularly for prophylactic platelet transfusions, by reducing the l eukocyte content of components by leukocyte-reduction filters and, pos sibly, by ultraviolet-B irradiation of leukocyte-containing, products.