MHC-Ⅱ-independent anti-tumor mechanisms of CD4+ cytotoxic T lymphocytes (CD4 CTLs). CD4 CTLs can secret effector cytokines, IFN-γ and TNF-α, that (1) induce senescence-associated growth arrest in tumor cells, (2) destruct tumor blood vessels, and (3) stimulate immune effector cells, such as CD8+ T cells (“CD8 T”), natural killer cells (“NK”), and macrophages (“Mø”), to kill tumor cells.
