Brief DetTnitive Report LOW DOSE RADIOSENSITIVITY OF ALLOIMMUNE CYTOTOXIC T CELLS* BY CRAIG SPELLMAN AND ROBERT E. ANDERSON

The effects of ionizing radiation on the immune system relate primarily to the radiosensitivity of the small lymphocyte. Within the past several years, as our concepts of cell-cell interactions have evolved with emphasis on functional subsets of lymphocytes, it has become clear that subpopulations differ in their radiosensitivity (1). Further, the lymphocyte is unique, in that radiation-induced cell death occurs not only at the time of cell division but also immediately after exposure. This latter type of injury is called interphase cell death (1). The purpose of the present study is twofold: (a) to determine the radiosensitivity of the cells which express cytotoxic effector activity with particular emphasis on very low dose (10-25 rad) gamma irradiation, and (b) to determine the Lyt phenotype and proportion of radiosensitive cells susceptible to interphase death.