Immune pathophysiology of acquired aplastic anemia.

Acquired aplastic anemia (AA) is a hematopoietic dyscrasia characterized by pancytopenia and bone marrow hypoplasia. AA is considered to be caused mainly by T-cell attacks on hematopoietic stem cells, as assumption based on good responses to T-cell specific immunosuppressive therapy (IST). Several markers, such as HLA-DRB1(*)1501 and an increase in the percentage of paroxysmal nocturnal hemoglobinuria (PNH) phenotype cells, have been shown to represent the immune pathophysiology of AA. However, little is known about the pathogenesis of AA. This review article focuses on immune mechanisms underlying the development of AA and the roles of the aforementioned markers in the management of bone marrow failure.