Low mucosal-associated invariant T-cell number in peripheral blood of patients with immune thrombocytopenia and their response to prednisolone.

Mucosal-associated invariant T (MAIT) cells help protect against certain infections and are related to some autoimmune diseases. Immune thrombocytopenia (ITP) is a relatively rare hematological autoimmune disease associated with low platelet count. We designed a cross-sectional study wherein we examined peripheral blood samples of patients with ITP for the number of MAIT cells (CD3+TCR-Vα7.2+CD161+IL-18Rα+ lymphocytes) and their CD4/8 subsets (by flow cytometry) and levels of cytokines (by multiplex assays). The study cohort included 18 patients with ITP and 20 healthy controls (HCs). We first compared the number of MAIT cells between HCs and patients with ITP and then performed subgroup analysis in patients with ITP. The number of total MAIT cells in patients with ITP was significantly lower than that in HCs (p < 0.0001), and the CD4-CD8+ subset of MAIT cells showed the same trend. Moreover, patients with ITP refractory to prednisolone exhibited a significantly lower number of total MAIT and CD4-CD8+ MAIT cells than patients sensitive to prednisolone. The number of total MAIT and CD4-CD8+ MAIT cells was not correlated with the response to thrombopoietin receptor agonist treatment or with Helicobacter pylori infection. We found no relation between cytokine levels and response to prednisolone treatment, although the levels of IP-10 and RANTES showed a correlation with the number of total MAIT and CD4-CD8+ MAIT cells. In conclusion, total MAIT and CD4-CD8+ MAIT cells in peripheral blood were decreased in patients with ITP, correlating with their response to prednisolone.