Acquired Aplastic Anemia and Bone Marrow Transplantation

By definition aplastic anemia is described as pancytopenia with empty bone marrow in which the marrow is replaced by fat cells. The etiology of acquired aplastic anemia is largely unknown; however in one third of the patients it is associated with either viruses, drugs or chemicals.1 The way in which these agents produce aplastic anemia is unknown but it has been suggested that both stem cells and micro envi-ronmental factors play a part.2 As far as pathogenesis of the disease is concerned, there is little doubt about the immune mediated destruction of the stem cells. Activated CD8+ lymphocytes may play a role in inducing production of gamma interferon, which lead to nitrous oxide synthesis in stem cells causing apoptosis.2 It is also confirmed by the response of the disease to immunosuppressive agents. Without treat-ment, it is invariably a fatal disease with a mortality of 80 % at one year. However, age at presentation and absolute neutrophil count are important prognostic factors.3,4 They also guide the physician to pla