Depressed in vitro lymphoproliferation after radiation therapy

Mixed lymphocyte culture (MLC) responses and lymphocyte proliferative responses to phytohaemagglutinin (PHA) stimulation were determined before and after pelvic irradiation with 40 Gy in 10 patients with endometrial carcinoma stage I. The MLC responses were depressed after irradiation, and were not normalized after adherent cell depletion. Adherent cells did not significantly suppress the responses of non-adherent lymphocytes. Indomethacin could not restore the depressed PHA responses occurring after irradiation. Autologous posttreatment serum was not suppressive. The results favour the assumption that irradiation causes immunodepression by injuring the responding cells or some amplifier system, rather than by activation of suppressor systems. (Auth.)