Increased IFN-gamma(+) and TNF-alpha(+) mucosal-associated invariant T cells in patients with aplastic anemia

Background: Aplastic anemia (AA) is known as an autoimmune disease in which T cell activation is aberrant. It has been reported that unconventional T cells, mucosal-associated invariant T (MAIT) cells, play an important role in several autoimmune diseases, but it is unclear if they are involved in AA.Methods: In this study, we for the first time analyzed the proportions, phenotypes, and cytokine properties of MAIT cells in AA by flow cytometry.Results: We found that the percentage of circulating MAIT cells was generally higher for CD3(+), CD8(+), and CD8(-) T cells in AA patients compared with healthy individuals. Moreover, the percentage of IL-18R alpha-, NKG2D-, IFN-gamma-, and TNF-alpha- positive MAIT cells was also significantly higher in AA patients. In addition, the percentage of IFN-gamma(+) CD3(+) or TNF-alpha(+)CD8(-) MAIT cells had a significant negative correlation with the absolute neutrophil count.Conclusions: We present the first observation of MAIT cells in patients with AA. MAIT cells are associated with a higher frequency of IFN-gamma and TNF-alpha production and may contribute to the pathogenesis of AA.