Treatment of platelet‐alloimmunization with cyclosporin a in a patient with aplastic anemia

The development of alloantibodies to platelets is a major problem in the supportive management of thrombocytopenia in patients with severe aplastic anemia. We report here a case of aplastic anemia refractory to platelet transfusion. An immunosuppressant, cyclosporin A, which was used for the therapy of aplastic anemia, modulated alloimmunization to platelets in this patient, followed by repeated platelet transfusion. The treatment reduced platelet alloantibodies detected by anti-human immunoglobulin lymphocytotoxicity test, with change of the CD4/CD8 ratio in T lymphocytes in peripheral blood. These results suggest the usefulness of cyclosporin A for the prevention of platelet alloimmunization.