Mucosal‐associated invariant T cell alterations in adults with recent-onset and long-term oral lichen planus

Objectives Mucosal-associated invariant T (MAIT) cells play key roles in many immune-inflammatory diseases. However, their characteristics between the long-term course of oral lichen planus (OLP) and recent-onset OLP remains unknown. In this study, we aimed to investigate the function of MAIT cells in different process of OLP and to explore the immunological background of this disease. Methods The frequency, phenotype, cytokine secretion of MAIT cells and its clinical relevance by flow cytometry from the peripheral blood of 14 adults with recent-onset OLP (7-120 days after disease onset) and 16 adults with long-term course (>2 years after diagnosis) compared with 15 healthy blood donors. Statistical analyses were performed using the GraphPad Prism software. Results MAIT cells from adults with recent-onset OLP harbored an activated phenotype, as indicated by an increased frequency of CD69 ⁺ ( p  < 0.05) and CD38 ⁺ MAIT cells ( p  < 0.01) and elevated production of proinflammatory cytokines IL-17A ( p  < 0.01), compared with healthy adult donors. In adults with long-term OLP, MAIT cells exhibit an activated and exhausted phenotype, characterized by high expression of CD69 ( p  < 0.01) and PD-1 ( p  < 0.001), as well as increased production of the granzyme B released by MAIT cells ( p  < 0.01). Compared with recent-onset OLP patients, long-term OLP patients show a decrease in the production of CD8 ⁺ , and CD4 ⁻ CD8 ⁻ cells but an increase in PD-1 ⁺ production ( p  < 0.05). Conclusions The frequency, phenotype, and function of MAIT cells are more altered in adult OLP patients with long-term onset than in those with recent-onset OLP. Clinical Relevance With the prolonged course of OLP, MAIT cells play different functional roles.