Comparison of the in vitro cytolytic effect of hepatic, splenic and peritoneal macrophages from glucan-treated mice on sarcoma M5076.

Our previous results have demonstrated that glucan will significantly modify the course of syngeneic murine tumors. Additionally, results denote that glucan increases macrophage-mediated lysis of syngeneic tumor cells. The present study was undertaken to more closely examine the effect of parenteral glucan administration on the tumoricidal activity of hepatic, splenic and peritoneal macrophage populations. C56B1/6J mice were injected intravenously with glucan (0.45 mg/mouse) on days 1,3,6,9,12 and 15. Hepatic, splenic and peritoneal macrophages were isolated on days 8, 12 and 16. The macrophages were co-incubated for 72 h with syngeneic reticulum cell sarcoma M5076 at a target: effector ratio of 1:50. A significant increase in the cytolytic activity of all three macrophage populations was observed. Kupffer cell tumoricidal activity was increased (p less than 0.01) on day 8, but was not significantly different from control on days 12 and 16. Peritoneal exudate macrophages showed increased (p less than .001) tumoricidal activity on days 12 and 16, respectively. Splenic macrophages showed an enhanced (p less than 0.01) increase in lytic activity only on day 16. The present results indicate that: 1) glucan will enhance macrophage-mediated tumoricidal activity of three distinct macrophage populations and 2) a temporal relationship exists between glucan administration and expression of lytic activity by the macrophage populations. These observations further define the mechanism by which glucan exerts its potent anti-tumor activity.