Lysosomal exocytosis induced by hyperthermia: a new model of cancer cell death. II. Effect on peritoneal macrophages.

Recently we described the "macrophagic lysosomal exocytosis" (MLE) as a possible new mode of cancer cell death induced by hyperthermia (HT) [1]. In order to confirm this first report, HT was applied at the peritoneum level with perfusional procedure, after catheter insertion under local anesthesia. We evaluated the subcellular changes of peritoneal macrophages in human gastric tumor, before and after hyperthermic treatment at 42 degrees C for 90 minutes. Transmission electron microscopy showed that treatment produced the disappearance of the cytoplasmic granules, with a consequent extracellular scavenger action of the phagocytic cells, the proliferation of some organelles such as mitochondria, endoplasmic reticulum and Golgi complex that may be addressed to a subsequent restoration of the granular pool in the degranulated macrophages. This phenomenon can enhance the already documented effect of hyperthermic perfusional chemotherapy in peritoneal tumors.