Fatal aplastic anemia in a child with Down's syndrome.

An infant with Down's syndrome developed severe persistent neutropenia at the age of 9 months and fluctuating anemia and thrombocytopenia at one year of age which terminated as full-blown aplastic anemia at 26 months of age. Immunological evaluation revealed increased peripheral and bone marrow lymphocytes and impaired blood OKT4: OKT8 ratio. Bone marrow granulocyte-macrophage colony forming cells (GM-CFC) were markedly increased, while peripheral blood mononuclear cells (PBMN) produced normal numbers of colonies. The patient's PBMN and serum were both somewhat inhibitory to normal bone marrow derived GM-CFC, suggesting the existence of a suppressor activity both in his serum and PBMN. This unusual course of aplastic anemia and the abnormalities in T-cells and hematopoiesis in Down's syndrome are discussed.