Association of mucosal-associated invariant T cells with different disease phases of polymyalgia rheumatica

OBJECTIVES: Although T cells are thought to be involved in the pathogenesis of PMR, whether innate-like T cells are involved in the process remains unknown. METHODS: The serum levels of 27 cytokines/chemokines in patients with PMR were measured by a multiplex immunoassay (Bio-Plex Assay). The cytokine-producing capacity of T and innate-like T cells was assessed by intracellular cytokine staining and flow cytometry. The frequency and activated status of T and innate-like T cells were investigated by flow cytometry and their associations with clinical parameters were assessed. RESULTS: The levels of inflammatory cytokines were associated with disease activity in PMR. The cytokine-producing capacity by CD8+ T and innate-like T cells was associated with disease activity. The frequency of HLA-DR+ CD38+ cells among CD8+ T cells was increased in patients with active disease. The frequencies of HLA-DR+ CD38+ cells among CD4+ T, mucosal-associated invariant T (MAIT) and gammadelta T cells were higher in patients with inactive disease. The frequency of HLA-DR+ CD38+ MAIT cells was associated with the PMR activity score and CRP levels in patients in remission. CONCLUSION: The inflammatory cytokine-producing capacity and expression of activation markers of CD8+ T and innate-like T cells were associated with the disease activity of PMR. MAIT cell activation in patients in remission may contribute to the subclinical activity of the disease.