A comparative analysis of mucosal associated invariant T cells and invariant natural killer T cells

• ¹ University of Oxford, Nuffield Department of Clinical Neurosciences, United Kingdom
• ² Advanced Medical and Dental Institute, University of Science, Malaysia, Cluster of Regenerative Medicine, Malaysia
• ³ Quest International University Perak, Department of Pharmacology, Faculty of Medicine, Malaysia
• ⁴ University of Oxford, Experimental Medicine Division, United Kingdom

Background CD1d-restricted invariant natural killer T (iNKT) cells and MR-1-restricted mucosal associated invariant T (MAIT) cells are two subsets of non-conventional T cells, with conserved T-cell receptor (TCR) repertoire, functions, homing and cytokine production. Both cell types show remarkable differences in their abundance in humans and mice; iNKT cells are found at a higher frequency in mice than human, whereas the opposite situation is true for MAIT cells. This suggests that the T cell subsets can potentially replace the other. Since MAIT cells dominate CD161++CD8+T cell population, the aim of this study is to compare the common phenotypes and roles between CD161++CD8+ T and iNKT cells. Methods CD161++CD8+ T and iNKT cells were characterised in terms of chemokine and cytokine receptor expression and functionality. This study compared peripheral blood iNKT cells and MAIT cells from healthy individuals. Since CD161 is widely expressed by lymphocytes, flow cytometry was employed to analyse the two study populations at the single cell level, and distinguish them from other CD161 expressing cells. Results Both cell types displayed preferential tissue-homing molecules, and different subsets of CD4/CD8 cell. Some of the Th17 characteristics were also found in iNKT cells, like IL23R and CCR6. In the present study, both the cells expressed granzyme A, K and perforin, with lower/undetectable expression of granzyme B. CD161++CD8+T cells were also observed to express higher levels of D prostanoid receptor (DP) 1 at the cell surface and at the mRNA level when compared to those seen in iNKT cells. Conclusions CD161++CD8+ T and iNKT cells are distinctive from conventional T cells. Both these cells are selectively recruited to the site of inflammation and exhibit antimicrobial activity. Although some overlapping functions were observed between these populations, differences were detected in the cytokine expressions and cytolytic granule contents.