Immunologic status of host and response of a methylcholanthrene‐induced sarcoma to local x‐irradiation

Abstract

A methylcholanthrene‐induced fibrosarcoma of C3H/He mice has been submitted to a series of TD50 and TCD50 assays. TD50 is number of cells to transplant tumor into half of the recipients; TCD50 is radiation dose which yields control of half of the irradiated tumors. The TD50 was greater by a factor of 100 for transplantation into actively immunized mice instead of 400 rads whole body irradiated animals (24 hours earlier). The TCD50 values were 4,300 rads, 3,500 rads, and 2,700 rads for tumors transplanted into immunologically depressed mice, normal mice, and actively immunized mice, respectively. This difference in TCD50 would correspond to a killing by radiation dose of 100 times fewer cells in the actively immunized mice than in 400 rads' irradiated mice. There was no effect of the radiation‐induced changes in normal tissue to block the efficacy of the immune rejection response to increase TD50. Finally, attempts to enhance the immunologic rejection response being mounted by a normal mouse against an established tumor were not successful. Copyright © 1970 American Cancer Society