Measurement of human serum erythropoietin by erythroid colony-forming technique using fetal mouse liver cells.
A quantitative bioassay for serum erythropoietin in anemic patients was established with erythroid colony-forming technique using methyl cellulose. Fetal mouse liver contains many erythropoietin-dependent erythroid colony-forming cells (CFU-E) with the concentration as well as sensitivity to erythropoietin being the highest at 13-14 days of gestation. Linearity in the erythropoietin response curve for the number of colonies from CFU-E in fetal livers of 13-14 days gestation was obtained for erythropoietin concentrations in the culture medium of 3.9 to 125 mU/ml. When newborn liver cells were used instead, the linearity occurred at 31.2 to 250 mU/ml. Measurement of erythropoietin by the erythroid colony-forming technique for sera from patients with various anemias was compared with that of the assay method using radioiron incorporation into heme in the suspension culture of fetal mouse liver cells. There was a good correlation between the values of both assay methods (r = 0.856, p less than 0.001). Also, levels of erythropoietin measured by this assay method showed the expected inverse relationship to the hemoglobin concentration in the sera from the patients.