PDCD1 and neoplasm: Increased expression of tumor PD-L1 suppressed cell cytotoxicity and cytokine secretion of TCR-T cells in vitro, while the diverse capabilities of scRNA transcriptome analysis revealed that both anti-inflammatory and pro-inflammatory responses were triggered by the increased expression of tumor PD-L1, providing possible explanations for the contradicting results of using tumor PD-L1 expression to predict clinical efficacy of anti-PD-1/PD-L1 therapies.