Thermal enhancement of radiosensitivity in normal and ataxia telangiectasia human cells.

Normal human and ataxia telangiectasia (AT) fibroblasts were tested for enhancement of radiosensitivity by hyperthermia. In normal fibroblasts, thermal enhancement of radiosensitivity occurred at 42.0 degrees C and 45.0 degrees C and was greatest for simultaneous treatments of heat and radiation. This thermal enhancement decreased, as an incubation time at 37.0 degrees C was introduced either between heat and X-ray, or X-ray and heat, treatments. AT cells were more radiosensitive (D0 = 0.67 Gy) than normal cells (D0 = 1.4 Gy). Heating at 42.0 degrees or 45.0 degrees C resulted in enhanced radiosensitivity, which was equal for heating before, during or after irradiation. These data show that normal human fibroblasts can recover from heat and radiation treatments, while AT fibroblasts lack this ability.