Severe autoimmune thrombocytopenia after allogeneic bone marrow transplantation for aplastic anemia

Autoimmune thrombocytopenia (AITP) after bone marrow transplantation (BMT) was suggested to occur by immune dysregulation mainly in association with g raft-versus-host disease (GVHD). Here we present a patient who developed se vere AITP after BMT. A 40-year-old woman with severe aplastic anemia receiv ed a BMT from a partially HLA-matched brother. Despite myeloid and erythroi d engraftments, platelet recovery was delayed. All bone marrow cells were 4 6,XY and were derived from the donor. Grade I acute GVHD involving skin dev eloped from day 34 posttransplantation, but promptly responded to prednisol one in addition to a prophylactic dose of tacrolimus. With the tapering of prednisolone, thrombocytopenia progressed without substantial changes in th e white blood cell count, hemoglobin concentration, or reticulocyte count. On day 188, the patient developed chronic GVHD involving skin and liver, wh ich promptly responded to the readministration of prednisolone and increase d tacrolimus. However, the patient's platelet count decreased to 9 x 10(9) cells/L on day 222. The platelet-associated immunoglobulin G (PAIgG) values were elevated. Bone marrow examination showed hypercellularity with plenti ful megakaryocytes. The number of colony-forming units-megakaryocyte was wi thin the normal range. The elevated PAIgG values and a correlation between thrombocytopenia and the intensity of the immunosuppressive agents strongly suggested a causative role of the autoimmune mechanisms for thrombocytopen ia in this patient. (C) 2001 The Japanese Society of Hematology.