Effects of low doses of irradiation on the T-cell-mediated cytotoxic response.

Statistically significant inhibition of the T-cell-mediated cytotoxic response was observed when mouse splenocytes were irradiated in vitro with 0.15 Gy prior to ConA and allogeneic stimulation. Restimulation in mixed lymphocyte culture demonstrated the same difference between irradiated and non-irradiated cultures as for the first stimulation. Adherent cell depletion of responder cells did not modify the inhibitory effect of 0.15 Gy on the cytotoxic response. The study of Lyt-6 markers on activation showed a decrease in the total number of activated cells (but not of the percentage) in cultures processed with irradiated cells. The data suggest that a T cell, involved in the generation of cytotoxic lymphocytes and present in the Lyt-2-depleted population, is the target of low-dose irradiation.