Combined effect of X-ray and bleomycin on cultured mammalian cells

Investigations were carried out with cultured mammalian cell lines to assess the effect of combination of radiation and Bleomycin. When cells were treated with the antibiotic before and during exposure to X-rays, a slight potentiating effect was consistently found. The magnitude of potentiation of the radiation effect appeared to depend on the concentration of Bleomycin. When the cells were treated pulsewise at various periods after irradiation, the potentiating effect was found only during the first 2 hr. Simultaneous application of X-rays and Bleomycin provided the greatest effect.