title: Effects of irradiation on PHA-induced T-lymphocyte colonies: differential effects according to the timing of irradiation.
abstract: To investigate the effect of irradiation on lymphocyte mitosis we utilized a T-lymphocyte colony assay; this sensitive technique avoided the methodological problems associated with previous techniques such as tritiated thymidine uptake. Irradiation doses in the range of 0.5 to 4 Gy had the effect of decreasing the lymphocytes' capacity to divide as shown by their reduced T-colony-forming ability. This radiosensitivity, however, was found to vary according to the timing of irradiation in relation to the stage of colony growth. Through survival curve analysis it was shown that the colony-forming cells could withstand higher irradiation doses without losing their replicative ability when they were irradiated prior to or during early stages of PHA stimulation. A similar "protection" by PHA stimulation has been well documented for nondividing T-lymphocyte functions but, due to the lack of a suitable methodology, had hitherto not been described for dividing T-lymphocytes. These results provide evidence that the early events associated with PHA stimulation might lead to an improved ability of T-lymphocytes to withstand higher doses of irradiation before mitotic death is registered.
mesh_terms: D002455:Cell Division / Q000187:drug effects / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D002478:Cells, Cultured; D003114:Colony-Forming Units Assay; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D008938:Mitosis / Q000187:drug effects / Q000528:radiation effects; D010835:Phytohemagglutinins / Q000494:pharmacology*; D013601:T-Lymphocytes / Q000187:drug effects / Q000528:radiation effects*; D013997:Time Factors
chemical_list: D010835:Phytohemagglutinins