Prevention of alloimmunization in patients with acute leukemia by use of white cell‐reduced blood components—a randomized trial

Platelet refractoriness arising from HLA alloimmunization is a serious complication of transfusion therapy. In a prospective randomized trial, white cell (WBC)‐reduced blood components were compared to standard platelet and red cell concentrates with respect to alloimmunization, refractoriness, and platelet increments after transfusion. Sixteen of 31 adult acute leukemia patients received only WBC‐reduced platelet concentrates (PCs) and red cells (RBCs), with fewer than 10 6 WBCs per unit. Fifteen control patients received standard blood components with a mean of 0.1 × 10 9 (PCs) and 1 × 10 9 (RBCs) WBCs per unit. Platelet loss during cotton‐wool filtration averaged 14 percent (range, 3–32%) from fresh PCs and 24 percent (range, 9–62%) from stored PCs. Filtration did not change corrected increments (CI) measured after transfusion of fresh PCs. The Cl 1 hour after filtration of stored PCs diminished by 27 percent, but the difference was smaller after 18 hours, which suggests better survival of WBC‐reduced platelets. The number of platelet units transfused did not differ in the two groups. No patient in the WBC‐reduced group developed permanent platelet refractoriness; transient HLA antibodies of low titer developed in two patients. In the control group, one patient became refractory because of immunization and two developed transient HLA antibodies. It can be concluded that the reduction of WBCs in blood components can effectively prevent alloimmunization.