[The role of the hematopoietic microenvironment in the mechanism of the antiradiation action of prodigiozan].

Preliminary administration of a radioprotective dose (3 mg/kg) of the bacterial polysaccharide prodigiozan 24 hours before irradiation of (CBA X X C57B1) F1 hybrid mice by a dose of 8 Gr increased the efficacy of exogenous clone formation of intact and irradiated bone marrow significantly. The efficacy of exogenous clone formation increased by 44-82% in transplantation of intact bone marrow and by 180-220% in transplantation of irradiated marrow (as compared to the values in animals who did not receive prodigiozan). This phenomenon was evidently associated with intensified reproduction of the transplanted CFU in mice given prodigiozan, evidence of which is the quantitative dependence of the effect on the dose of the transplanted cells. A conclusion is drawn that one of the aspects of the hematopoiesis-stimulating effect of prodigiosin in an irradiated organism is linked with its effect on the elements of the hematopoietic stroma. It is suggested that agents of other classes may be characterized by a similar mechanism of action; the same effect may be produced by some other factors which reduce radioresistance.