VARIABLE EXPRESSION OF IL-1-BETA HAS MINIMAL EFFECT ON THE RADIATION SENSITIVITY OF 3 HUMAN GLIOMA CELL-LINES

Interleukin I(IL-I) has been reported to act as a radioprotector in vi vo. Data from our laboratory and from other investigators suggest that glioma cell lines can produce bioactive cytokines including IL-I and also express IL-I receptors. In view of the putative radioprotective e ffect of this cytokine, we have examined the in vitro radiosensitivity of three human glioma cell lines with widely varying levels of endoge nous IL-I beta. The data reveal that when irradiated (2 Gy/min) as con fluent cultures (conditions optimal for differential IL-I beta express ion), and plated for colony formation after postirradiation holding, c ell survival was not correlated with level of IL-1 beta mRNA expressio n. Retinoic acid has been shown to dramatically enhance levels 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 radio protector in these cells under these experimental conditions.