An experimental study of enhanced cell killing by hyperthermia and bleomycin.

In vitro cell killing effects from heating and/or bleomycin have been investigated using the KK-47 cell line derived from a human bladder carcinoma and the colony-forming assay system. Percent survivals of the asynchronous cells heated to 40 degrees, 41 degrees, 42 degrees and 43 degrees C for 30 min were 96.6%, 93.3%, 91.4% and 71.2%, respectively, and those at 43 degrees C for 2h were 80.6%, 75.5%, 46.0% and 1.4%, respectively. The survival percentages of the cells treated with bleomycin at the concentrations of 1, 3, 6 and 10 micrograms per ml at 37 degrees C for 30 min were 66.0%, 40.4%, 21.9% and 11.9%, respectively. When hyperthermia at 43 degrees C was combined with bleomycin, a greatly enhanced cell killing effect was obtained by preheating and simultaneous heating as compared with the effect of post-heating.