Abstract
The mechanism of selective suppression of T‐cell activity in Ehrlich tumor‐bearing mice was investigated in an adoptive cell transfer system of secondary antibody responses to haptens. The induction of secondary antidinitrophenyl (DNP) antibody response after stimulation with DNP‐homologous carrier (TD) of thymus‐dependent DNP‐carrier (TD)‐primed spleen cells was markedly inhibited in tumor‐bearing recipient mice, whereas the response to thymus independent DNP‐carrier (TID) was intact as compared to that seen in normal recipients. However, if tumors were induced in the DNP‐TD‐primed donor mice and the spleen cells were assayed for responsiveness to DNP‐TD in normal recipients, they generated a normal anti‐hapten antibody response. After the DNP‐TD‐primed cells had been transferred into normal recipients and tumors had been induced in the recipients before DNP‐TD‐stimulation, the cells in tumor‐bearers responded normally. These results indicate that the tumor‐bearing state neither directly suppresses the responsiveness of primed cells nor interferes with the mechanism for antigen stimulation of primed cells. Direct measurement of recovery of transferred primed T and B cells from the spleen of tumor‐bearing recipients revealed that the net recovery of T‐cell activity markedly decreased, whereas the recovery of B cells in the spleens of tumor‐bearing hosts was not affected or was even higher than the normal. Prevention of repopulation by T lymphocytes of lymphoid organs due to a postulated change in the microenvironment is suggested as a mechanism for the selective suppression of T‐cell activity in Ehrlich tumor‐bearing animals.