Enhancement of T cell MLR reactivity by addition of macrophage supernatants from tumor-bearing mice.

One-way mixed lymphocyte reactions (MLR) were used to establish a correlation between loss of in vitro T cell reactivity and in vivo tumor growth. Though supernatants from anti-Thy 1 treated macrophages (M phi) greatly enhanced MLR activity in normal T cells, such addition had little effect in reversing the inability of T cells from 2-week palpable tumor-bearing mice (TBM) to recognize in vitro foreign histocompatibility antigens. Since normal T cells, exposed to TBM M phi supernatants, exhibited no decrease in proliferative response, TBM T cell loss of MLR reactivity could not be ascribed to tumor-induced suppressor M phi.