Abstract
BACKGROUND: Mucosal-associated invariant T (MAIT) cells are involved in acute ischemic stroke in mice models. This study aimed to clarify the dynamics and role of circulating MAIT cells in patients with acute ischemic stroke. METHODS: Patients with acute ischemic stroke were classified according to the National Institutes of Health Stroke Scale into severe (score ≥ 10) and mild (score < 10) groups; outpatients with matched sex and age were selected as controls. Circulating MAIT cells, activation (CD69+), and cytokine production (IFN-γ [interferon-gamma] + and IL-17 [interleukin-17]+) on days 3, 10, and 17 after stroke, along with invariant natural killer T cells, gamma delta T cells, CD4+, and CD8+ T-cell populations, were analyzed by flow cytometry. The relationship between MAIT cell dynamics and clinical outcomes was examined. RESULTS: One hundred participants (30 severe, 40 mild, 30 controls) were included. On day 3, patients with severe stroke had a significantly lower proportion of MAIT cells than the mild group and controls (severe, mild, control [median]: 0.09%, 0.33%, 0.38%, respectively; P < 0.001), which gradually recovered on day 17. Severe stroke MAIT cells showed higher frequencies of CD69 expression and IL-17 production. Multivariate analysis showed patients in the lowest MAIT cell population quartile on day 3 had a significantly higher probability of poor outcomes at 3 months than those in the highest quartile (odds ratio, 21.64 [95% CI, 1.41-331.58]; P = 0.027). CONCLUSIONS: An early decrease in MAIT cells with higher activity and proinflammatory cytokine production correlated with stroke severity and poor outcomes, suggesting a significant role of MAIT cells in acute cerebral infarction and unfavorable outcomes.