Interestingly, a recent study revealed that PD-L1+ eosinophils—identified as active eosinophils with a T cell regulatory function via single-cell transcriptomics in a mouse model of colitis (more on this later)—exhibited significant abundance in PD-L1 samples from patients with ulcerative colitis (UC) and Crohn's disease compared to healthy controls (58). This evidence concerns the gene CD274 and ulcerative colitis.