Effects of interleukin-23 on the activation of mucosal-associated invariant T cells from oral lichen planus

OBJECTIVE: Oral lichen planus (OLP) is a T cell-mediated inflammatory condition in the oral cavity. Mucosal-associated invariant T (MAIT) cells are gaining more relevance in immune diseases because they can be activated by cytokines without T cell receptor stimulation. Herein, we tested the effect of interleukin-23 (IL-23) on the activation status of OLP MAIT cells. METHODS: Peripheral blood mononuclear cells (PBMCs) isolated from OLP patients were stimulated by IL-23 in the absence or presence of phorbol myristate acetate (PMA) and ionomycin. The activation status of MAIT cells was analyzed by flow cytometry after staining for CD3, CD4, CD8, CD161, TCR Vα7.2, and CD69. RESULTS: The fraction of MAIT cells in OLP peripheral blood was approximately 0.38% to 3.97%, and CD8(+) subpopulations overwhelmed CD4(+) cells. The mean percentages of OLP MAIT cells in PBMCs and CD8(+)MAIT cells in MAIT cells were approximately 40%. PMA and ionomycin significantly increased CD69 expression on OLP T cells, MAIT cells, and CD8(+)MAIT cells. Cells with enhanced activation had different responsiveness to exogenous IL-23, showing increased CD69 expression on OLP T cells, decreased CD69 on OLP CD8(+)MAIT cells, and no significant change on OLP MAIT cells. CONCLUSIONS: IL-23 showed different effects on the activation status of OLP MAIT cells and CD8(+)MAIT cells.