Identification and characterization of an 8-kd peptide stimulating late erythropoiesis

Chronic renal failure is often associated with severe anemia, subnormal levels of erythropoietin (EPO), and the presence of erythropoietic inhibitors. We studied an anephric patient with polycystic kidney disease maintaining a hemoglobin level of 13-14 g. Biochemical, endocrine, and hematological parameters were all within normal limits. EPO levels examined on two occasions during the clinical investigation were found to be low to subnormal. Plasma of this patient supported human bone marrow erythroid colony formation without the addition of exogenous EPO. Following reversed-phase high pressure liquid chromatography (HPLC) and gel filtration HPLC of the patient's plasma, a small polypeptide was identified that stimulated thymidine incorporation into fetal calf liver cells and supported erythroid colony formation of human marrow cells. This molecule is different from EPO with respect to its molecular weight and its functional and chromatographic properties. In this report we provide evidence of a human plasma-derived peptide of an anephric patient regulating late erythropoiesis.