Hyperthermia enhances X ray cell killing in normal and homozygous and heterozygous ataxia telangiectasia human cells.

Two homozygous and heterozygous ataxia telangiectasia (AT) cell strains were compared to normal human cells for heat and radiation responses. The thermal sensitivities to one hour heating at 42.0 degrees C were comparable in the five cell strains. Thermal enhancement of radiosensitivity occurred in both homo- and hetero-zygous AT cell strains and was comparable to the thermal enhancement observed in the normal cell strain. Normal cells recovered during incubation at 37.0 degrees C between the two treatments of heat and X rays while homozygous AT cells showed no recovery. The heterozygous cell strains showed only a slight sequence dependence for heat and radiation sensitivity.