[Radiation protection through cytokine release by N-acetylcysteine]

Interleukin-1, tumornecrosisfactor-alpha and interferon-gamma endogenously provide protection of the hematopoietic system against radiation. Thiols have already been used successfully as radioprotective agents. In this study the effect von N-acetylcysteine (NAC) on the release of interleukin-1 alpha and beta (IL-1), interleukin-2 (IL-2), interferon-gamma (IFN-gamma) and tumornecrosisfactor-alpha (TNF-alpha) was assessed in an in vitro assay.

Whole blood samples from 8 healthy volunteers were stimulated with 7.5 micrograms/ml PHA. NAC was added at concentrations of 0.6, 6, 12 and 24 mmol/l. Subsequently the samples were irradiated with a dose of 18 Gy according to preceding validation experiments.

IL-1 alpha, IL-1 beta b and IL-2: In comparison to stimulation and radiation alone the addition of 0.6 and 6 mmol/l, with IL-2 also 12 mmol/l, NAC resulted in a significant increase of the cytokine-concentrations. The highest concentration of 24 mmol/l NAC, however, resulted in a decrease beyond control levels. IFN-gamma and TNF-alpha: Until 12 mmol/l NAC no changes were observed. 24 mmol/l NAC resulted in a significant decrease, too.

N-acetylcysteine is capable to co-stimulate radioprotective cytokines like IL-1 alpha and IL-1 beta and to enhance IL-2 in vitro, whereas higher doses result in a suppression.