Effects of in vitro hyperthermia on murine and human lymphocytes

The effect of in vitro hyperthermia on the immune response of murine and human lymphocytes was investigated. Viability, blastogenesis and cytotoxic activity of murine lymphocytes were reduced at 39 and 42 degrees C hyperthermia. In human lymphocytes, rosette formation inhibition depended on heating-time and temperature. PHA-induced lymphocyte blastogenesis was markedly inhibited at 42 degrees C, irrespective of the duration of exposure and of the origin of the cells, although it was enhanced in some patients at 39 degrees C. Therefore, the possibility of hyperthermia-induced inhibition of the host immune response must be considered in clinical trials of total-body hyperthermia for cancer.