Variable expression of IL-1 beta has minimal effect on the radiation sensitivity of three human glioma cell lines

Interleukin 1 (IL-1) has been reported to act as a radioprotector in vivo. Data from our laboratory and from other investigators suggest that glioma cell lines can produce bioactive cytokines including IL-1 and also express IL-1 receptors. In view of the putative radioprotective effect of this cytokine, we have examined the in vitro radiosensitivity of three human glioma cell lines with widely varying levels of endogenous IL-1 beta. The data reveal that when irradiated (2 Gy/min) as confluent cultures (conditions optimal for differential IL-1 beta expression), and plated for colony formation after postirradiation holding, cell survival was not correlated with level of IL-1 beta mRNA expression in the two IL-1-expressing cell lines. However, this was not correlated with a further reduction in radiosensitivity. These data indicate that IL-1 beta does not act as an endogenous radioprotector in these cells under these experimental conditions.