CD34 and inflammatory bowel disease: CD34 is used as a marker of ICC and TCs to evaluate their role in intestinal inflammation (Ricci et al., 2018; Wang et al., 2021); CD34+ TCs in the intestine during IBD significantly increase and are involved in eosinophil infiltration (Ricci et al., 2018); CD34+ ICC are decreased in ulcerative colitis, and ICC decrease is related to the increase of pathogenic bacteria in the small intestine during inflammation (Chen et al., 2017; Li et al., 2019).