Positive effect of granulocyte-colony stimulating factor on erythropoiesis in humans.

We studied the effects of granulocyte-colony stimulating factor (G-CSF) on human erythropoiesis in vivo. Changes in the peripheral blood were analyzed in 9 subjects; 3 healthy volunteers, 3 patients with pancytopenia and hypersplenism and 3 patients with chronic renal failure and severe anemia being treated with hemodialysis. We monitored erythropoiesis according to the number of highly fluorescent cells (HFC) present in the peripheral blood after staining with Auramine 0. These cells are relatively immature reticulocytes that contain much RNA. All subjects received recombinant human G-CSF at a daily dose of 100 micrograms/m2 administered intravenously for 3 to 5 days. Plasma erythropoietin was measured in patients receiving dialysis before and several times after its administration. The number of HFC increased significantly in all subjects. In 1 of 3 patients receiving dialysis, the plasma erythropoietin increased transiently but insignificantly. These findings show that G-CSF affects human erythropoiesis in vivo, but that the mechanism of its effect did not involve an increase in plasma erythropoietin.