Aplastic anemia and pure red cell aplasia.

The role of known hematopoietic growth factors in the pathogenesis of aplastic anemia and congenital hypoplastic anemia has been extensively studied and no evidence has been obtained that deficiency of these factors contributes to the hypoproliferative state in these disorders. Clonal hematopoiesis seems to be present at least in a small percentage of cases of aplastic anemia, a finding that needs further investigation. Androgens were shown to be beneficial only for women with aplastic anemia treated with antilymphocyte globulin. Unrelated-donor bone marrow transplantation is becoming a realistic approach for children and very young adults with aplastic anemia, but in older groups the survival is very poor. New observations on abnormalities of lymphokines and cytokines in Fanconi's anemia have been described, but their pathogenetic significance remains unknown. A large number of studies have excluded the possibility that abnormalities of c-kit/SCF genes and their expression are responsible for the erythroid aplasia in Diamond-Blackfan syndrome. Cyclosporine was found to be an effective treatment for pure red cell aplasia associated with chronic lymphocytic leukemia. The cell membrane receptor for B19 parvovirus has been identified as the P antigen. Long-term studies showed that in 20% of patients with homozygous sickle cell disease, infection by B19 does not cause erythroid aplasia.