title: Survival and PHA-stimulation of gamma-irradiated human peripheral blood T lymphocyte subpopulations.
abstract: Human peripheral blood T lymphocyte subpopulations were identified and isolated on the basis of their ability to bind IgG (T-G), IgM (T-M), or neither immunoglobulin class (T-null). Lymphocytes were exposed to 0, 0.5, 1.0, 2.5 or 5.0 Gy of 60Co gamma-rays either as a T-cell suspension or as separated T cell subsets. Survival curves, determined 5 days after irradiation, revealed that each subset has radiosensitive and radioresistant portions, and that the T-G cell is the most sensitive subset. Mitotic indices of 48-h cultures showed that the response of unirradiated T lymphocytes to PHA varied greatly among the subsets, the highest indices being obtained for the T-M and the lowest for the T-G cells. With the possible exception of the T-G cells, the subsets are relatively resistant to mitotic effects of gamma-rays. T-G cells suppress the PHA-induced mitotic response of the other T lymphocyte subsets, and this suppressor effect is radiosensitive, being abolished by 1.0 Gy. It is concluded that lymphocytes exposed to greater than or equal to 1 Gy of gamma-rays will have very few dividing B lymphocytes or T-G cells. This together with radiation-induced loss of T-G suppressor action means that the predominant lymphocyte types in mitosis after greater than or equal to 1 Gy are the radioresistant T-M and T-null cells.
mesh_terms: D002470:Cell Survival / Q000528:radiation effects; D005720:Gamma Rays; D006801:Humans; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D066298:In Vitro Techniques; D008213:Lymphocyte Activation / Q000528:radiation effects*; D010835:Phytohemagglutinins / Q000494:pharmacology; D011836:Radiation Tolerance; D013601:T-Lymphocytes / Q000145:classification / Q000276:immunology / Q000528:radiation effects*; D050378:T-Lymphocytes, Regulatory / Q000528:radiation effects
chemical_list: D007074:Immunoglobulin G; D007075:Immunoglobulin M; D010835:Phytohemagglutinins