PDCD1 and neoplasm: Interestingly, administration of butyrate and anti-PD-1 increased the percentage of IFN-γ+ and TNF-α+ in tumor infiltrating CD4+ and CD8+ T cells compared to treatment with anti-PD-1 or butyrate alone (Figure 3k–m), whereas the expression of antitumor related cytokines in γδ+ T cells was either unchanged or only marginally increased (Fig. S3g-i).