[Aplastic anemia].

In vitro cultures of hemopoietic precursor cells and clinical studies have partly clarified the pathogenesis of aplastic anemia. The defect is located both in the hemopoietic precursor cells and in their microenvironment. The therapeutic possibilities have enormously improved. Allogeneic bone marrow transplantation remains largely limited to young patients with an HLA-identical sibling donor. In our experience successfully transplanted patients are completely cured. Mortality from rejection, graft-versus-host-disease and infection has been markedly reduced. Immune modulating therapy with ALG produces high remission rates but residual defects in hemopoietic precursor cells remain and clonal disorders such as paroxysmal nocturnal hemoglobinuria may ensue. Despite of this ALG is the treatment of choice for patients without an HLA identical sibling donor.