Activation of murine mononuclear phagocytes for destroying tumor cells: analysis of effector mechanisms and development.

Abstract

Over the past decade, the original concept of macrophage activation as development of the ability to destroy facultative or obligate intracellular parasites has been broadened to include the destruction of tumor cells (1). Macrophages from sites of infection with such intracellular parasites, when cocultivated with tumor cells, efficiently destroy the tumor cells over several days (1). This form of cytolysis, which has been termed macrophage-mediated tumor cytotoxicity, has generally been found to be selective for tumor cells, to depend upon cell-to-cell contact, and to be independent of either exogenous recognition factors or soluble lytic substances (2,3). In the past two years, it has become apparent that macrophages can also be activated for destroying tumor cells in another, quite distinct circumstance — the lysis of antibody-coated tumor targets (antibody-dependent cellular cytotoxicity or ADCC) (4,5). Considerable evidence has been amassed that activation of macrophages is an important host defense against the development and spread of neoplasms in vivo (1–3).