IFNG and neoplasm: Therefore, co-culture with peripheral blood T lymphocytes (PBTLs) may inhibit the production of IFN-γ from T cells, thereby inhibiting the anti-tumor immune response [69, 70].Interestingly, in another study, researchers found that restricting glutamine consumption by tumors up-regulated the expression of tumor PD-L1, by reducing the expression of GSH in the tumor cells.