PDCD1 and neoplasm: In tuberculosis lung tissues, clonally expanded CD8+ and CD4+ T cells exhibit reduced expression of exhaustion markers (e.g., PDCD1, TIGIT, LAG3, SNX9, PELI1) and exhaustion-related transcription factors (e.g., TOX, GATA3, BATF, RUNX2, PRDM1), indicating impaired T cell exhaustion compared to tumor and non-tumor lung tissues [63–66].