Mechanisms of Immunity to Sarcoma I Allografts in the C57BL/Ks Mouse. I. Passive Transfer Studies With Immune Peritoneal Macrophages in X-Irradiated Hosts

Summary

Passive transfer of immunity to Sarcoma I (Sal) allografts was demonstrated by sublethal inoculation of X-irradiated C57BL/Ks mice subcutaneously with mixtures of immune peritoneal macrophages and Sal cells. The degree of suppression of tumor growth was directly related to the number of immune macrophages added to the tumor inoculum. When inocula containing tumor cells and macrophages in ratios of 5:1, 2:1, and 1:1 were used, tumor growth was suppressed significantly. Tumor growth was unaffected when cells in the ratio of 10:1 were used. When immune macrophages were injected intraperitoneally and tumor cells were inoculated subcutaneously, no inhibition of tumor growth was noted. We studied the growth of the ascites form of Sal by mixing the inoculum of tumor cells with immune macrophages in ratios of 10:1, 4:1, 2:1, and 1:1. Tumor suppression was obtained only with inocula in which the tumor cells and immune macrophages were in ratios of 2:1 and 1:1. The results indicate that macrophages contribute significantly to the rejection of Sal allografts in the C57BL/Ks mouse. Moreover, they support the concept that the tumor-suppressive action of macrophages demands contact with the tumor cells.