The effect of hyperthermia on activation of lysosomal enzymes in HeLa cells

Abstract The activity of lysosomal acid phosphatase has been studied by a quantitative cytochemical method in HeLa cells subjected to hyperthermic treatment, lysosomal enzyme activity has been related to cell survival. Incubation of cells for 0.5–5 hr at temperatures greater than 37°C causes an increase in lysosomal enzyme activity with a very marked increase over the range 42–44°C . Enzyme activation occurred immediately after heat treatment and increased linearly with time over the period 0–90 min . The effect of heat on lysosomal enzyme activation was pH dependent and much more effective at pH 5.6 than at pH 7.2 . An inverse relationship between lysosomal enzyme activation and cell survival has been demonstrated. It is concluded that activation of lysosomal enzymes is an important and early event in cellular injury caused by hyperthermia.