Skin- and gut-homing molecules on human circulating γδ T cells and their dysregulation in inflammatory bowel disease

Changes in phenotype and function of ?d T cells have been reported in inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC). Dysregulation of lymphocyte migration plays a key role in IBD pathogenesis; however, data on migratory properties of ?d T cells are scarce. Human circulating ?d T cells from healthy controls (n = 27), patients with active CD (n = 15), active UC (n = 14) or cutaneous manifestations of IBD (n = 2) were characterized by flow cytometry. Circulating ?d T cells in healthy controls were CD3hi and expressed CD45RO. They expressed gut-homing molecule beta 7 but not gut-homing molecule corresponding chemokine receptors (CCR)9, or skin-homing molecules cutaneous lymphocyte-associated antigen (CLA) and CCR4, despite conventional T cells containing populations expressing these molecules. CCR9 expression was increased on ?d T cells in CD and UC, while skin-homing CLA was expressed aberrantly on ?d T cells in patients with cutaneous manifestations of IBD. Lower levels of CD3 expression were found on ?d T cells in CD but not in UC, and a lower proportion of ?d T cells expressed CD45RO in CD and UC. Enhanced expression of gut-homing molecules on circulating ?d T cells in IBD and skin-homing molecules in cutaneous manifestations of IBD may be of clinical relevance.