A possible role of activated macrophages in the adoptive immunotherapy using CD4+ T lymphocytes

Potent anti-tumor T lymphocytes with CD4+8- phenotype were obtained in peritoneal exudate cells by immunizing mice with irradiated tumor cells and OK-432. These effector cells were used in adoptive immunotherapy for tumor-bearing mice. Admixed administration of effector T cells with irradiated relevant tumor cells resulted in a marked enhancement of anti-tumor activity against local tumor and lymph node metastasis compared with the immunotherapy by effectors alone. The activating state of macrophages inoculated with viable tumor cells had much relevance with the implementation of immunotherapy. Innocent bystander lysis was not observed in this immunotherapy. Interleukin-2 given instead of stimulant tumor cells caused no enhancement, while interleukin-1 emerged stronger enhancement than stimulant tumor. In this case, activating state of macrophages had no relevance with the effectiveness of the therapy. These results suggest that macrophages in tumor play a role to secrete interleukin-1 to enhance anti-tumor activity of specific T cells.