Effect of radiation therapy on the mitogenic response of in vitro irradiated human lymphocytes to phytohaemagglutinin.

Irradiation of human peripheral lymphocytes in vitro reduces their capacity to be triggered to DNA-synthesis by PHA in a two-dose shaped fashion suggesting the presence of one relatively radiation sensitive and one relatively resistant cell population. Intracavitary and external radiation therapy for carcinoma of the uterus and vagina, which reduced the lymphocyte counts by approximately 66 per cent, did not significantly change the ratio of these subpopulations, indicating that PHA-reactive cells cannot be grouped into radiation sensitive and resistant subpopulations.