Cyclosporin for treatment of life-threatening alloimmunization

We describe a 16-year-old girl with aplastic anemia who, 1 year after initial diagnosis developed a refractory state to platelet transfusions due to alloimmunization and resulting in severe bleeding. Treatment with cyclosporin, initially prescribed as treatment of the bone marrow failure, resulted in prompt decrease in lymphocytotoxic antibodies, which paralleled a marked improvement in platelet recovery. To our knowledge, such a dramatic effect of cyclosporin on alloimmunization has not been previously reported and merits further attention.