Leukotrienes and Prostaglandins Mutually Govern the Antitumor Potential of Macrophages

Macrophages, due to their phagocytosing and secretory function, are effector cells and because of their interaction with lymphocytes, are also looked upon as surveillance cells of the immune system. Eicosanoids, derived from either the cyclooxygenase or the lipoxygenase pathways of arachidonic acid metabolism, are readily synthesized by macrophages and in turn these substances have regulatory effects on both the effector and surveillant functions of these cells. Macrophages also are thought to play a role in host defense against malignant neoplasia by exerting deleterious effects on tumor cells. This article discusses the connection between the regulatory effects of eicosanoids on macrophages, on the one hand, and the damaging activity of these cells towards malignant cells, on the other. Besides reviewing the most salient earlier findings, account of our recent experiments and their interpretation in the light of the function of macrophages in host defense towards tumors will be given.