Alloimmunization following platelet transfusions in patients with acute nonlymphocytic leukemia.

Lymphocytotoxic (LCT) antibodies were measured in 20 adult patients with acute nonlymphocytic leukemia (ANLL) who received remission induction chemotherapy and multiple platelet transfusions. Nine (45%) became LCT positive and refractory to the platelet transfusions. This frequency of alloimmunization in ANLL patients was significantly lower than that in aplastic anemia patients (p less than 0.05). In one male with acute promyelocytic leukemia (APL), the LCT antibody disappeared during intensive chemotherapy and recovery of transfused platelets improved remarkably. The incidence of alloimmunization in the patients with APL appeared to be especially low. Six out of 9 LCT positive patients with ANLL became alloimmunized with less than 10 units of platelet transfusions. Three out of 11 LCT negative patients never became alloimmunized with more than 100 units. These facts indicated that there was no relationship between the number of platelet transfusions given and the development of alloimmunization. In addition, the remission rate also did not correlate with the development of alloimmunization.