USE OF A MACROPHAGE CYTOTOXICITY SYSTEM TO SHOW MACROPHAGE ACTIVATION BY LISTERIA-MONOCYTOGENES CELL-WALL FRACTION

Experiments were conducted to determine whether a partiulls purified listeria cell wall fraction could stimulate macrophages to high levels of activation. To detect activation of macrophages. a macrophage‐mediated cytotoxicity system was established. The data demonssrate that listeria cell wall components are capable of activating thioglycollate‐induced adherent peritoneal exudate cells to be cytotoxic for 51Cr‐labelled target tumour cells, and that the listeria fraction is as effective as bacterial lipopolysaccharide in inducing cytotoxicily. The listeria fraction can also induce peritoneal exudate cells from congenitally thymusless nude mice to become cytotoxic, suggesting that mature T cells are not required. Furthermore, thioglycollate‐induced adherent peritoneal exudate cells from mice hyperimmunized to live Listeria organisms are already stimulated to be cytotoxic for tumour cells, and do not need to be aciivated in vitro. Additional data are presented which characterize the system. These data demonstrate that a critical concentration of adherent peritoneal cells is required for in vitro activation. Moreover, only peritoneal cells induced with aged batches of thioglycollate, and not uninduced peritoneal cells or those induced with fresh thioglycollate or with protease peptone can be activated in vitro to kill tumour cells. Evidence is presented which suggests that the cyloioxic cell is a macrophage Copyright © 1979, Wiley Blackwell. All rights reserved