CD27 and inflammatory bowel disease: In treatment-naive IBD patients at the time of diagnosis, researchers identified four distinct T cell maturation profiles based on CD45RA and CD27 expression, with the A profile, enriched with CD45RA + CD27 + naïve T cells, being observed exclusively in the ileum/colon of IBD patients and correlating with increased TNF-α expression and reduced IFN-γ expression [39].