Effect of radiation on the production of interleukins and T-lymphocyte activities

The effect of 0-400 rad ⁶⁰Co γ-ray doses on distinct steps in the process of murine T-cell activation by concanavalin A (Con A) was investigated. When C57BL/6 spleen cells were stimulated immediately after irradiation, production of interleukin-1 (IL-1) and interleukin-2 (IL-2) was not impaired. Concomitantly, the display of IL-2 receptors in Con A-induced reactivity to IL-2 was not affected. The proliferative response was markedly diminished by increasing doses of radiation. The effect of radiation was found to depend not only on the delivered dose but also on the time interval between irradiation and stimulation of the lymphoid cultures. When the mitogenic stimulus was delayed for 24 hours following irradiation, IL-1 production was not diminished, whereas IL-2 production was impaired by doses greater than 200 rad. The proliferative response was diminished to a markedly higher degree as compared to the degree it was diminished in cell cultures stimulated by Con A immediately after irradiation. IL-2 production and the proliferative response to Con A of irradiated cell suspensions, cultured without mitogen for 24 hours post irradiation, were also assessed after adjustment for cell death. In this case, an impairment in IL-2 production that was dose dependent was apparent, but still the levels of IL-2 secreted by 400-rad irradiated cells reached high levels. In contrast, the proliferative response to Con A could not be restored. When T-cell growth factor was added concomitantly with Con A to irradiated cell cultures, a radioprotective effect could be observed.