Peritoneal macrophage cytotoxicity induced by serum in vitro

The authors studied the effects of peritoneal macrophages on the growth of HP2 cells, a continuous line isolated from the transplanted Harding-Passey mouse melanoma. They found that normal peritoneal macrophages can exert a strong cytostatic effect on HP2 cells, as expressed by cell number and tritiated thymidine uptake by the target cells. The data indicates that normal heat inactivated sera from various species can render macrophages cytostatic. In addition, normal serum can amplify the cytostatic properties of macrophages from immunized animals. The results are discussed in the light of present knowledge of macrophage metabolism.