Innate immunity, such as MR1-dependent MAIT cell response, is essential for host defense against bacteria. Yet the key cells mediating MR1 antigen presentation were unclear. Recently, McWilliam and colleagues identified macrophages as the dominant MR1-expressing cells responsible for presenting microbial antigens to activate antibacterial MAIT cells and regulate microbiota composition.
Qiao et al. (Fri,) studied this question.