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 (MATT) and gamma delta T cells were higher in patients with inactive disease. The frequency of HLA-DR+ CD38(+) MATT 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. MATT cell activation in patients in remission may contribute to the subclinical activity of the disease.