Effects of x-rays and bleomycin on cultured mammalian cells

The cultured brain tumor cells and established cell lines, HeLa S3 and L5, were exposed to X-rays, with and without combinations of bleomycin, and the reproductive capacity and growth curves of these treated cells were assayed. No enhancement of the cell killing effect was observed when cells were treated with bleomycin following irradiation, while preliminary bleomycin treatment sensitized the cells to irradiation. No division delay was observed in cell reproductively surviving the bleomycin treatment, even though the concentrations of bleomycin were sufficient to reduce the survivals to less than 10%. An attempt to determine the conversion factor for evaluating X-ray doses in bleomycin equivalents failed because the order of the radiosensitivity of these cells was different from that of the sensitivity to bleomycin treatment. (author)