ACTIVITY OF HUMAN PERITONEAL-MACROPHAGES AGAINST A HUMAN TUMOR - ROLEOF TUMOR-NECROSIS-FACTOR-ALPHA, PGE2 AND NITRITE, IN-VITRO STUDIES

Human peritoneal macrophages collected from renal patients on continuo us ambulatory peritoneal dialysis (CAPD) during inflammation-free peri ods were induced to express antitumor activity in vitro when cultured in the presence of bacterial lipopolysaccharide (LPS) and even more ac tivity when they were kept in the presence of LPS + IND (indomethacin) . The antitumor activity was expressed against a human tumor-cell line , RC43, either in a cell-to-cell contact set-up between the macrophage s and the RC43 target cells or when the tumor cells were exposed to su pernatants of the cultured macrophages. The antitumor activity of macr ophages was correlated to a marked increase in production of tumor nec rosis factor-alpha (TNFalpha), not correlated to an increase in nitrit e production and inversely correlated to the production of PGE2. The R C43 tumor cells were susceptible to recombinant human TNFalpha, recomb inant human IL-1beta, sodium nitrite and the leukotriene LTB4. The res ults obtained suggest that activated human macrophages might represent a useful tool for cancer immunotherapy.