PDCD1 and colitis: Similarly, compared to healthy colons and colitis-naïve ICI patients, ICI-colitis patients have been reported to have higher proportions of activated CD8+ (HLA-DR+CD38+), and to a lesser extent CD4+, TRM cells with high expression of RNA transcripts related to immune checkpoints such as CTLA4, PDCD1, TIGIT, TIM-3, and LAG-3 in addition to activation genes such as IFNG, HLADR, GZMB, and PRF1 (112).