[Stimulation of the postradiation recovery of hematopoiesis in irradiated animals using a calf splenic extract].

The injection of a purified cytoplasmic supernatant from calf splenocytes to lethally irradiated mice and hamsters favors the recovery of haemopoiesis and increases the survival rate. Proteins of 50--75 kDa molecular mass, having no specific features but being highly labile, are responsible for the radiobiological effect. The enzymic characteristics of the purified extract permit to suggest that the inhibitors of DNAase I and Ca2+, Mg2+-endonucleases are involved in the postirradiation transformations in the exposed animals.