Intraperitoneal macrophages and tumor immunity: A review

The macrophage (M phi) is considered the first line of defense in immune re sponse to foreign invaders. Increasing evidence suggests that M phis also p lay an important role against neoplastic cells. M phis exposed to supraphys iologic concentrations of CO2 are suppressed. As surgeons apply newer minim ally invasive techniques to oncologic therapies, it is important to evaluat e the impact of these techniques on host-tumor interactions. We review the current understanding of M phi biology with specific attention on cytotoxic ity in addition to tumor immunity. Although systemic immune function is bet ter preserved after laparoscopy than laparotomy, peritoneal M phis show red uced function after CO2 pneumoperitoneum than exposure to air. M phis have shown cytotoxicity to syngeneic cancer cells and may play an important role in tumor surveillance. The impairment in M phi function after CO2 exposure may have an effect on outcome after oncologic surgery. In our understandin g, M phis help destroy neoplastic cells. As CO2 impairs M phi activity, lap aroscopy may significantly alter the host-tumor interaction. J. Surg. Oncol . 2000:75:146-155. (C) 2000 Wiley-Liss, Inc.