Discrimination Between Neoplastic and Non-Neoplastic Cells In Vitro by Activated Macrophages12

Abstract

A modification of cellular function, termed “activation,” converted macrophages into cytotoxic effector cells. Tumor cells were destroyed by a non phagocytic mechanism under in vitro conditions in which normal target cells were spared and grew to confluency. A biochemical change, probably in the cell membrane, appeared to make tumor cells more susceptible than normal cells to destruction by activated macrophages. This surveillance system, which is based on a nonimmunologic interaction between activated macrophages and target cells, may be related to a phylogenetically and ontogenetically primitive recognition system.