Oxygen enhancement of radiation induced lethality is greatly reduced in glutathione deficient human fibroblasts.

The in vitro clonogenic survival of human fibroblasts with a genetically defined glutathione (GSH) deficiency was studied after irradiation with X-rays in oxygen or in oxygen free argon. Genetically related fibroblasts without GSH deficiency were used as a control. The oxic survival curve of both cell lines was similar. In comparison to the oxic survival curve, the anoxic survival curve of GSH deficient cells indicated an oxygen enhancement ratio (OER) approximately 1.5. An OER approximately 2.9 was calculated in comparing the oxic and anoxic survival curves of the control cell line. The results were discussed in support of the theory according to which oxygen and GSH compete for radiation induced radicals in key molecules, the former irreversibly fixing and the latter repairing the radiation damage.