The Mode of Action and Nature of a Heat Stable Plasma Erythropoietic Factor

Boiled filtrates of "anemic" rabbit plasma have been studied by physicochemical means, and the response to their injection into the rat has been followed utilizing tracer and morphologic technics. It has been demonstrated that the erythropoietic activity of these filtrates is associated with an alpha-2 globulin, most probably a mucoprotein; and that this material produces, in the rat, an increase in the rate of red cell division and maturation, and an acceleration of release of these cells from the bone marrow and accessory organs of hemopoiesis.