[Radioprotective and therapeutic modulation of thymus gland regeneration in rats after x-ray irradiation].

There have been studied effects of cystaphos, gammaphos, hydroxyurea, polyadenyl-polyuridinic acids (poly A:poly U) as well as the combination of gammaphos and poly A:poly U, that is, cystaphos and superoxide dismutase on the thymus of Wistar and AO rats irradiated by the hard X-rays in the dose of 5 or 3.5 Gy. Changes were observed up to 30 days after irradiation. The most efficacious protective effect has shown cystaphos (358 mg/kg i.p. 20 min. after irradiation) in Wistar rats irradiated by the dose of 3.5 Gy. It lowered involutive changes and accelerated thymus regeneration. On the basis of phenotypic analysis of thymocytes it can be supposed that such a favourable effect is the consequence of a larger protection of the cortical (strong OX 7+) thymocytes. Differing from cystaphos, transplantation of the syngeneic cells of the bone marrow in AO rats irradiated by the dose of 5 Gy showed favourable effect on thymus regeneration in later phase after irradiation preventing secondary thymus involution.