Unscheduled DNA-synthesis in UV-irradiated spleen lymphocytes of the rat after whole-body X-irradiation.

Unscheduled DNA-synthesis of UV-irradiated spleen lymphocytes of the rat is inhibited in a dose-dependent manner by total-body X-irradiation. The reaction is observed immediately after exposure and reaches its maximum within 8--16 h. Doses of some rads are detectable. Following sublethal X-irradiation (250 rad), regeneration takes 4--6 weeks. Analogous results have been obtained in rats treated with 2,4,6-triethyleneimino-1,3,5-triazine. Regardless of the action mechanisms, it is concluded from the present results that the inhibition of the unscheduled incorporation of thymidine-3H in splenic lymphocytes is a very sensitive, though not specific expression of impairment of the lymphatic system.