Normal erythropoietic helper T cells in congenital hypoplastic (Diamond-Blackfan) anemia

To examine the erythropoietic function of T and null cells in congenital hypoplastic (Diamond-Blackfan) anemia, the authors fractionated the peripheral blood of three normal subjects and three affected patients into subclasses of null, T and B cells. Mixtures of these cells were co-cultured in plasma clots in the presence of erythropoietin. Erythroid colonies grew in cultures of normal null cells if either normal or patient T cells were co-cultured with them. Null cells of patients with hypoplastic anemia did not produce erythroid colonies under any culture conditions. It is concluded that in this disorder, T cells function normally as helper cells in erythropoiesis and do not suppress colony formation, whereas the erythroid progenitor cells in the peripheral blood null-cell fractions are deficient in either number or function.