PRF1 and neoplasm: Compared with IgG2b treatment, CD8 mAb administration markedly enhanced tumor growth, decreased CD8+ T cell infiltration, and suppressed the cytotoxic effect of T cells (as indicated by GzmB+ CD8+, TNF-α+ CD8+, perforin+ CD8+ and IFN-γ+ CD8+ T cells) in CTRL LLC cell-inoculated mice, confirming that CD8+ T cells are pivotal for antitumor immunity maintenance (Fig. 2J-M).