%A Xiao,Xingxing %A Li,Kun %A Ma,Xueting %A Liu,Baohong %A He,Xueyang %A Yang,Shunli %A Wang,Wenqing %A Jiang,Baoyu %A Cai,Jianping %D 2019 %J Frontiers in Immunology %C %F %G English %K pigs,Immunity,T cell receptors,Mucosal-associated invariant T (MAIT) cells,phenotype %Q %R 10.3389/fimmu.2019.02070 %W %L %M %P %7 %8 2019-September-03 %9 Original Research %# %! MAIT cells in pigs %* %< %T Mucosal-Associated Invariant T Cells Expressing the TRAV1-TRAJ33 Chain Are Present in Pigs %U https://www.frontiersin.org/articles/10.3389/fimmu.2019.02070 %V 10 %0 JOURNAL ARTICLE %@ 1664-3224 %X Mucosal-associated invariant T (MAIT) cells are a subpopulation of evolutionarily conserved innate-like T lymphocytes bearing invariant or semi-invariant TCRα chains paired with a biased usage of TCRβ chains and restricted by highly conserved monomorphic MHC class I-like molecule, MR1. Consistent with their phylogenetically conserved characteristics, MAIT cells have been implicated in host immune responses to microbial infections and non-infectious diseases, such as tuberculosis, typhoid fever, and multiple sclerosis. To date, MAIT cells have been identified in humans, mice, cows, sheep, and several non-human primates, but not in pigs. Here, we cloned porcine MAIT (pMAIT) TCRα sequences from PBMC cDNA, and then analyzed the TCRβ usage of pMAIT cells expressing the TRAV1-TRAJ33 chain, finding that pMAIT cells use a limited array of TCRβ chains (predominantly TRBV20S and TRBV29S). We estimated the frequency of TRAV1-TRAJ33 transcripts in peripheral blood and tissues, demonstrating that TRAV1-TRAJ33 transcripts are expressed in all tested tissues. Analysis of the expression of TRAV1-TRAJ33 transcripts in three T-cell subpopulations from peripheral blood and tissues showed that TRAV1-TRAJ33 transcripts can be expressed by CD4+CD8, CD8+CD4, and CD4CD8 T cells. Using a single-cell PCR assay, we demonstrated that pMAIT cells with the TRAV1-TRAJ33 chain express cell surface markers IL-18Rα, IL-7Rα, CCR9, CCR5, and/or CXCR6, and transcription factors PLZF, and T-bet and/or RORγt. In conclusion, pMAIT cells expressing the TRAV1-TRAJ33 chain have characteristics similar to human and mouse MAIT cells, further supporting the idea that the pig is an animal model for investigating MAIT cell functions in human disease.