[Effect on erythropoiesis of conditioned media of mammal erythrocytes].

It is known that a medium conditioned by erythrocytes (ECM) reduces 59Fe uptake into haem in hemopoietic cell cultures. In order to evaluate if the release of this factor in conditioned media is correlated with the whole erythrocyte surface, the same volume of packed erythrocytes of Mammals characterized by different MCV were incubated according to the method of Cole and Regan (1977). The influence of these conditioned media upon 59Fe uptake into haem in cultures of Guinea pig bone marrow cells was studied. Our results demonstrate that ECM of lamb erythrocytes (MCV = 28) caused a more marked depression of haem synthesis in vitro than ECM of calf (MCV = 34) and Guinea pig (MCV = 69) erythrocytes, and that this inhibitory effect is correlated to the MCV of considered erythrocytes.