Studies on the Recognition of Xenogeneic Cells by Nonimmune Macrophages. II. Separate Signals Triggered Cytostasis and Cytolysis

Abstract

Macrophages are capable of a wide spectrum of foreign recognition which enables them to carry out their role in protecting the organism against foreign invasion. Their discrimination between foreign material and self components is expressed by their ability to recognize as foreign and engulf viruses, bacteria, protozoa and inert particles. Macrophages have also been found to exert a cytostatic and cytotoxic effect on a variety of target cell types. Following activation of macrophages by a variety of conditions and agents (chronic infections of the host, lymphokines, endotoxins and serum factors), these active cells become tumoricidal. They acquire the capacity to discriminate between normal and malignant cells and are capable of destroying the tumor cells (1,2). It was also reported that immune or armed macrophages, derived from specifically immune hosts were cytostatic and/or cytotoxic in vitro against specific tumor or normal cells (3–5).