CD4 and neoplasm: Indeed, in addition to increasing T cell frequency, low-dose TSA and PD-L1 blockade cooperatively enhanced IFN-γ and TNF-α production by both CD4+ and CD8+ T cells (Fig. 6i), suggesting that this combination therapy not only improved tumor infiltration by T cells but also enhanced their effector activation and promoted T-cell-mediated cytotoxicity.