CD8A and neoplasm: Rather, the reduction in CAR+ CD8+ T cell population in the F9 model suggests that CD8+ T cells are integral for tumor rejection, and perhaps the presence of CAR+ CD4+ T cells or CAR+ NKs are required to prime and coordinate the overall immune response, providing sufficient activation either through direct contact or via cytokine secretion to facilitate the actions of CAR+ CD8+ T cells.