Constancy of erythroid burst forming unit (BFUE) levels in the blood of hematologically normal individuals.

Repeated determination of circulating blood BFUE levels in 7 hematologically normal individuals, during a 6 to 16 month period, showed their respective levels to be maintained within narrow limits (coefficient of variation did not exceed 15.1%). However, males differed from each other 3-fold and females as much as 12-fold in the number of BFUE/ml blood. These differences may reflect various sizes of the early erythroid progenitor compartment, which in the presence of different levels of humoral regulators of erythropoiesis are capable of maintaining a normal rate of red cell production. Our findings suggest that the observation of changes of the blood BFUE level of individuals, over a period of time, may be indicative of a change in their erythropoiesis and may shed some light on the physiological role of the peripheral blood BFUE.