Mechanisms of Macrophage-Mediated Tumor Cytolysis

Important roles have been proposed for both cellular (1,2) and humoral (3–5) immunity in the complex host reaction to neoplastic growth. Killing of syngeneic tumor cells, at least in vitro, can be mediated by many different host cell types either alone or in combination with humoral factors. The mechanisms of tumor cell destruction by macrophages in particular have been studied extensively because of the known tumoricidal properties of macrophages (6–8) and the histological observation that these cells are capable of infiltrating various solid tumors in several different species (9).