Response of uraemic bone marrow cells to erythropoietin in vitro.

In vitro culture technique of bone marrow cells has been applied to study the cause of anemia in uraemic patients on maintenance haemodialysis. Incorporation of 59Fe into haem in bone marrow cells of the patients in the presence of erythropoietin, as well as the inhibitory effect of their plasma on the response of normal bone marrow cells to erythropoietin, was examined. Increase in haem synthesis rate by erythropoietin in the bone marrow cells of uraemic patients (n 14; 7.9 +/- 1.4) wasnot significantly different from that in normal bone marrow cells (n 9; 5.9 +/- 1.4,p greater than 0.05), thus indicating the presence of erythroid precursor cells with normal responsiveness to erythropoetin in uraemic patients. All the plasma from uraemic patients inhibited, in dose-dependent way, the response of normal bone marrow cells to erythropoietin. Levels of erythropoietin in the plasma samples of uraemic patients were much lower than those of the patients with iron deficiency anaemia with comparable Hb concentrations. On the basis of these results, the humoral inhibitory factor appears to play a significant role in the pathogenesis of renal anaemia, in addition to the low level of circulating erythropoietin.