Induction of thermotolerance in clonogenic cells of Lewis lung carcinoma

: The cell killing effect of hyperthermia (43 degrees C, 15 min) on the clonogenic Lewis lung carcinoma cells forming colonies in agar cultures in diffusion chambers was studied in vitro and in vivo. Survival rate of clonogenic tumour cells was 7.5 to 10.5%, the most prominent effect being observed in vitro. The preliminary heating resulted in 2-fold reduction of these cells' sensitivity to repeated hyperthermia. The thermotolerance effect persisted for 3 days after its induction.