The immunohistochemistry of the samples showed that anti-PD-1 induced colitis was characterized by a predominant infiltration of CD8+ T cells in the lamina propria and epithelium, while anti-CTLA-4 colitis was associated with CD4+ T cells accumulation in the lamina propria with high tumor necrosis factor (TNF)-α secretion. Here, CD4 is linked to colitis.