P100 CD161 levels are reduced in all subpopulations of T-cell colonic mucosal lymphocytes in inflammatory bowel disease

Abstract

Background CD161 is a type C lectin expressed in NKs cells and peripheral T cells (TCRγδ and αβ, NKTs), enriched in intestinal populations. Its expression can be modulated by infections and inflammation. MAIT cells are a subset of innate antimicrobial T-cells abundant in the mucosa but their role in immunological regulation is still unknown. Aim To measure CD161 levels in subtypes of T-lymphocytes of intestinal mucosa: CD4+, CD8+, double positive (DP,CD4+CD8+), double negative (DN,CD4−CD8−), MAIT cells (CD161+TCRVα7.2+) and intraepithelial cells (CD103+) Methods Twenty-six patients with active inflammatory bowel disease (IBD) without immunosuppressive treatment (n = 9 Crohn’s disease -CD- colon, 9 CD ileum, n = 8 ulcerative colitis -UC- and 10 healthy controls (paired biopsies of ileum, right and left colon) were included. Lymphocyte subpopulations were analysed with LSRFortessa cytometer. Non-parametric Kruskal–Wallis test was applied. Results are expressed as % of median (25–75%IQI). Results In healthy mucosa, we did not find differences related to location in any of CD161 subpopulations except for increase of CD3+CD161+CD103+ and decrease of CD3+CD161+CD103− in left colon compared with right colon and ileum. Regarding MAIT cells, a progressive decrease was observed in distal parts of intestine for CD3+MAIT+CD103+ while CD3+MAIT+CD103− subpopulation has a specular behaviour; CD3+CD8+MAIT+ was increased in ileum compared with colon (Table 1). Conclusion There is a regional specialisation for the subset CD103+ of both CD161+CD103+ and MAIT_CD103+ cells in healthy intestine. CD3+CD161+ T cells are reduced in IBD colonic inflammation and could serve as a marker of active IBD but not to sort between CD and UC.