[A role of postsurgical macrophage activation by peritoneal injury].

At a site of peritoneal injury after abdominal surgery, macrophages are thought to be a principle type of inflammatory cells. Therefore, we determined the metabolic activities of postsurgical peritoneal exudate macrophages using standardized rabbit model. Rabbits underwent midline laparotomy followed by resection and reanastomosis of the ileum. At various days after surgery, peritoneal exudate macrophages were recovered from lavage fluid. Postsurgical Day-5 macrophages expressed significantly high potential to produce superoxide anion even without PMA stimulation compared to non-surgical control macrophages, although an activity of Day-10 macrophages was similar to control. The conditioned media from postsurgical Day-1 macrophage culture strongly inhibited urokinase type plasminogen activator (PA) and this plasminogen activator inhibitor (PAI) activities decreased following the extension of postsurgical time. Conversely, PA activities of macrophage-conditioned media decreased by day 1 and then gradually increased reaching control levels by day 10. Elastase activities of macrophage-conditioned media gradually decreased until postsurgical day 10. These data suggest that surgical injury activates postsurgical exudate macrophages. However, a time course of metabolic activities of these cells was dependent upon each secretory products. This differential secretion might express the stage of activation and differentiation of postsurgical macrophages. Moreover, postsurgical activated macrophages may control the tissue repair through a digestion of injured matrix and fibrinolytic process.