Vaccines get a help-MAIT

Vaccines Mucosal-associated invariant T (MAIT) cells are a T cell subset important for mucosal homeostasis. These cells recognize derivatives of microbiota-derived vitamin B2 precursors but can also be activated by certain cytokines in the context of viral infections. Provine et al. report that a leading adenoviral vector vaccine, ChAdOx1, activated MAIT cells in immunized mice (see the Perspective by Juno and O'Connor). This activation required interferon-α produced by plasmacytoid dendritic cells as well as monocyte-derived interleukin-18 and tumor necrosis factor. MAIT cell activation positively correlated with vaccine-mediated T cell responses in human subjects, and mice deficient in MAIT cells showed impaired CD8+ T cell immunity to target antigens after vaccination. This work suggests an additional pathway that could be exploited to enhance the efficacy of vaccines. Science , this issue p. [521][1]; see also p. [460][2] [1]: /lookup/doi/10.1126/science.aax8819 [2]: /lookup/doi/10.1126/science.abf8121