Abstract
Summary: Methods were presented by which macrophages may be isolated from the peritoneal cell population of mice. These cells, and for comparison peritoneal lymphocytes and lymph node cells, were tested for immunologic activity by injecting a mixture of the test cells and tumor cells subcutaneously into irradiated mice. Each cell type, when obtained from immunized mice, was capable of suppressing the growth of the specific tumor cells. The results are discussed with respect to a possible specific immunologic function for macrophages in graft rejection.