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J Immunol. 2015 Oct 1;195(7):3472-81. doi: 10.4049/jimmunol.1500258. Epub 2015 Aug 21.

Human Mucosa-Associated Invariant T Cells Accumulate in Colon Adenocarcinomas but Produce Reduced Amounts of IFN-γ.

Author information

1
Department of Microbiology and Immunology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden;
2
Department of Surgery, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, 413 35 Gothenburg, Sweden;
3
Department of Microbiology and Immunology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden; Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 171 77 Stockholm, Sweden;
4
Department of Pathology, National University Hospital, Singapore 119074; and Department of Microbiology, National University, Singapore 119260.
5
Department of Microbiology and Immunology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden; marianne.quiding@microbio.gu.se.

Abstract

Mucosa-associated invariant T (MAIT) cells are innate-like T cells with a conserved TCR α-chain recognizing bacterial metabolites presented on the invariant MHC-related 1 molecule. MAIT cells are present in intestinal tissues and liver, and they rapidly secrete IFN-γ and IL-17 in response to bacterial insult. In colon cancer, IL-17-driven inflammation promotes tumor progression, whereas IFN-γ production is essential for antitumor immunity. Thus, tumor-associated MAIT cells may affect antitumor immune responses by their secreted cytokines. However, the knowledge of MAIT cell presence and function in tumors is virtually absent. In this study, we determined the frequency, phenotype, and functional capacity of MAIT cells in colon adenocarcinomas and unaffected colon lamina propria. Flow cytometric analyses showed significant accumulation of MAIT cells in tumor tissue, irrespective of tumor stage or localization. Colonic MAIT cells displayed an activated memory phenotype and expression of chemokine receptors CCR6 and CCR9. Most MAIT cells in unaffected colon tissues produced IFN-γ, whereas only few produced IL-17. Colonic MAIT cells also produced TNF-α, IL-2, and granzyme B. In the tumors, significantly lower frequencies of IFN-γ-producing MAIT cells were seen, whereas there were no differences in the other cytokines analyzed, and in vitro studies showed that secreted factors from tumor tissue reduced IFN-γ production from MAIT cells. In conclusion, MAIT cells infiltrate colon tumors but their ability to produce IFN-γ is substantially reduced. We suggest that MAIT cells have the capacity to promote local immune responses to tumors, but factors in the tumor microenvironment act to reduce MAIT cell IFN-γ production.

PMID:
26297765
DOI:
10.4049/jimmunol.1500258
[Indexed for MEDLINE]
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