Mucosal-associated invariant T (MAIT) cells are innate-like T cells involved in anti-bacterial im-munity. Recent studies have demonstrated that MAIT cells might be implicated in inflammatory bowel diseases (IBDs), but their precise function in IBD remains to be elucidated. We investigated the possible involvement of MAIT cells in the immunopathogenesis of IBDs. Heparinized peripheral blood and biopsy specimens of the colon were collected from 25 patients with ulcerative colitis (UC), 15 patients with Crohn's disease (CD), and 19 heathy individuals. Lymphocytes were isolated from the blood and colon, and then MAIT cells were analyzed by flow cytometry. The frequency of MAIT cells was significantly lower in the blood of IBD patients compared to healthy donors and significantly higher in the inflamed colons compared to healthy colons (P = 0.001). Among the IBD patients, the frequency of MAIT cells in the blood and colon was correlated with disease activities. In vitro activated MAIT cells from IBD patients secreted significantly more tumor necrosis factor-α and interleukin-17 than those from healthy donors. These findings indicate that MAIT cells are activated in IBD patients, and their accumulation in the inflamed mucosa is correlated with disease activities.Inflammatory bowel diseases (IBDs), including ulcerative colitis (UC) and Crohn's disease (CD), are chronic, relapsing inflammatory conditions of the gastrointestinal tract. Although host genetic susceptibility and environmental factors have been implicated in causing the disturbed homeostasis of the intestinal immune system that results in IBD, the exact etiology of IBD is still unknown (11,19,20). Genetic variants clearly play a central role in conferring risk for IBD, but a wide range of environmental factors, including smoking, diet drugs, social stress, and microbial factors, are also thought to confer risk for IBD (2). Accumulating evidence has suggested that among those environmental factors, the dynamic balance between commensal flora and host defensive responses within the intestinal mucosa plays a pivotal role in both the initiation and per-

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These findings suggested that MAIT cells were activated, exhausted, and persistently depleted in PBC patients even after ursodeoxycholic acid treatment, possibly as a consequence of persistent liver inflammation.

Background and Aim: Recent studies have demonstrated that B cells and follicular helper T (Tfh) cells, which are central regulators of humoral immune response, contribute to the development and progression of autoimmune diseases. Because Tfh cells can be divided into several subsets with distinct functional properties, this study aimed to examine the roles of different subsets of circulating Tfh cells in the immune pathogenesis of autoimmune hepatitis (AIH). Methods: Thirty-five patients with AIH, 28 patients with primary biliary cholangitis, 22 patients with chronic hepatitis B (CHB), and 44 health controls (HC) were enrolled. The frequencies of different Tfh subsets in the blood and liver were examined by flow cytometry and immunohistochemical staining. The function of circulating Tfh subsets was examined after in vitro stimulation. Results: In newly diagnosed AIH patients, the frequency of circulating chemokine C-C receptor 7À programmed cell death-1 + Tfh subset was significantly increased compared with that in CHB patients and HC, significantly correlated with clinical parameters, including serum IgG, prothrombin time and albumin levels, and significantly decreased after corticosteroid treatment. In the liver of AIH patients, the frequencies of activated Tfh subsets were significantly increased and positively correlated with those in the blood. Moreover, the ability to produce interleukin-21 and interleukin-17 from circulating Tfh cells was significantly increased in AIH patients compared with HC. Conclusions: These results significantly extend our understanding of Tfh subsets in AIH and suggest a potential role of dysregulated chemokine C-C receptor 7À programmed cell

Introduction Mucosal-associated invariant T (MAIT) cells are innate-like T cells that are involved in anti-bacterial immunity. MAIT cells are found in the intestines, but their role and distribution within the large intestine have not been fully elucidated. Therefore, we investigated the distribution of MAIT cells within the cecum and colon. Material and methods Surgically resected tissues of the cecum and colon were obtained from 4 patients with cecal appendix cancer and 8 patients with colorectal cancer, respectively. Lymphocytes were isolated from the intestinal epithelium (intraepithelial lymphocytes – IELs) and the underlying lamina propria (lamina propria lymphocytes – LPLs), and then, MAIT cells were analyzed by flow cytometry. Results Compared with the colon, the cecum showed a significantly increased frequency of MAIT cells among IELs (p < 0.01). CD69 expression on MAIT cells was significantly increased in the cecum and colon compared with that in the blood, and the frequency of natural killer group 2, member A + cells among MAIT cells was significantly increased in the cecum. Conclusions These results suggest that the distribution of MAIT cells was different between the cecum and colon and that MAIT cells were more likely to be activated, especially in the intestinal epithelium of the cecum than in the colon and blood.