Effects of irradiation doses on alterations in cytokine release by monocytes and lymphocytes.

We evaluated the effect of increasing doses of gamma-irradiation on the release of interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) from lymphocytes, and interleukin 1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) from monocytes. The most radiosensitive populations were the T lymphocytes which release IL-4 and IFN-gamma after irradiation alone. This release increased when the cells were activated by polyclonal activators such as Concanavalin A (Con A). Monocytes irradiated and stimulated with lipopolysaccharide (LPS) released TNF-alpha with values near those of the control cells. Con A produced no effect. The release of IL-1 beta decreased as the irradiation dose was increased, while stimulation with LPS and Con A caused a greater IL-1 beta increase after small irradiation doses. The results obtained show that minimum doses of irradiation can induce significant alterations in an amplified and unbalanced immunologic response through release of cytokines.