Effects of erythrocyte lysate and erythrocyte-conditioned medium on erythroid cells in vitro

A component of erythrocyte-conditioned medium has been shown to inhibit the incorporation of tritiated thymidine into erythroblasts from fetal mouse liver, proliferating in vitro. This component, however, has no detectable effect on the growth of colonies of erythroid cells stimulated to grow in viscous culture media by the hormone erythropoietin. Erythrocyte lysate and preparations of haemoglobin derived from the lysate increase the number and size of the colonies growing in vitro. Results are discussed in terms of possible control mechanisms in erythropoiesis.