THERAPEUTIC EFFECT OF ACTIVATED HUMAN MACROPHAGES ON A HUMAN TUMOR LINE GROWING IN NUDE-MICE

Human peritoneal macrophages were collected from dialysis bags of renal patients on Continuous Ambulatory Peritoneal Dialysis (CAPD), during an inflammation-free period. The macrophage suspension was cultured in presence of bacterial lipopolysaccharide (LPS) and phorbol myristate acetate (TPA). The cultured macrophages were tested for therapeutic effectiveness against a human tumor-cell line, RC43, implanted subcutaneously in NMRI nude mice. The macrophages were injected around the tumor starting from the 14th day after inoculation, when the tumor growth was already detectable (mean tumor size 7 mm). Three injections of macrophages on days 14, 18 and 21 induced hemorrhagic patches at the tumor site and almost complete regression of the tumor. One injection of macrophages cultured either in presence of LPS + TPA or of LPS + TPA + PGE2 resulted in marked slow-down of the tumor growth. Injection of either TNF-alpha (4000 U/mouse) or of PGE2 (150 ng/mouse) given at the site of the palpable small tumor had no effect. Macrophages cultured in medium or in medium supplied with either TPA, LPS or TPA + LPS, were not effective in nude mice bearing large (16 to 19 mm) tumors. The results obtained suggest that activated human macrophages might be therapeutically effective at certain stages of human cancer.