Isolation of a subpopulation of adherent peritoneal cells with anti-tumour activity

Abstract

WE have reported that adherent peritoneal cells from normal mice stimulated the growth of many lymphomas in vitro, while adherent peritoneal cells from mice injected with Bacille Calmette-Guerin (BCG) were far less stimulatory¹. The latter were overtly cytostatic when tested on L929 cells¹, as well as on several other adherent fibroblastic malignant targets (unpublished). This leads us to speculate that adherent murine peritoneal cells consist of at least two subpopulations, one that tends to stimulate and one that tends to inhibit the proliferation of susceptible target cells. According to this view, infection of the mouse with BCG might lead to increased numbers or activity of the cytostatic subpopulation at the expense of the stimulatory subpopulation. We have now isolated an adherent, esterase-positive, poorly phagocytic mononuclear peritoneal cell with potent tumour-inhibitory capacity, which may represent the postulated cytostatic subpopulation.