Suppression of transfusion-related alloimmunization in intensively treated cancer patients.

A retrospective review of HLA antibody testing and transfusion records of 100 cancer patients who required extensive platelet support revealed that 27 of 100 patients exhibited positive HLA antibody tests; only 13 remained positive on repetitive examination, while 88% of aplastic anemia patients so tested were positive. Sixty-five patients with leukemia, 16 with Ewing's sarcoma, and 19 with recurrent undifferentiated lymphoma were studied. Each patient received at least 10 U of platelets (mean of 72). HLA antibodies were detected in 31% (20/65) of the leukemias, 12% (2/16) of the Ewing's, and 26% (5/19) of the lymphoma patients. Fourteen of the 27 patients who developed antibodies became antibody negative again within 2 mo and remained so. There were no significant differences in quantity of platelet transfusions between antibody-negative patients and alloimmunized patients. A smaller group (n = 8) of aplastic anemia patients followed at the NCl exhibited a frequency of alloimmunization of 88% (7/8) after a mean of 44 U of platelets were transfused. Granulocyte transfusions given therapeutically for granulocytopenia and documented infection did not appear to influence HLA antibody formation. These data indicate that significant immunosuppression occurs in intensively treated cancer patients, as measured by their ability to from antibodies to HLA antigens expressed on the surface of transfused platelets.