Mucosal-associated invariant T (MAIT) cells are an innate-like T cell subset important in the early response to bacterial and viral lung pathogens. MAIT cells recognize bacterial small molecule metabolites presented on the Class I-like molecule MR1. As with other Class I and Class II molecules, MR1 can likely sample ligands in the intracellular environment through multiple cellular pathways. Rab6, a small GTPase that regulates a number of endosomal trafficking pathways including retrograde transport to the trans-Golgi network (TGN), is involved in the presentation of ligands from Mycobacterium tuberculosis (Mtb) to MAIT cells. The Rab6-mediated trafficking pathway contains endosomal compartments that share features with the Mtb intracellular compartment. Using inducible expression of MR1, this study demonstrates that Rab6 regulates the recycling of MR1 molecules from the cell surface through endosomal trafficking compartments to the TGN. This Rab6-dependent pool of recycled MR1, which is available for reloading with ligands from bacterial pathogens like Mtb, may be important for early recognition of infected cells by MAIT cells in the lung.

粘膜相关不变 T (MAIT) 细胞是一种先天样 T 细胞亚群，在对细菌和病毒肺病原体的早期反应中很重要。MAIT 细胞识别 I 类样分子 MR1 上呈现的细菌小分子代谢物。与其他 I 类和 II 类分子一样，MR1 可能通过多种细胞途径对细胞内环境中的配体进行采样。Rab6 是一种小 GTP 酶，可调节许多内体运输途径，包括逆行转运至跨高尔基网络 (TGN)，参与结核分枝杆菌配体的呈递(Mtb) 到 MAIT 细胞。Rab6 介导的运输途径包含与 Mtb 细胞内隔室共享特征的内体隔室。使用 MR1 的诱导型表达，本研究表明 Rab6 调节 MR1 分子从细胞表面通过内体运输隔室到 TGN 的再循环。这种依赖于 Rab6 的回收 MR1 池可用于重新装载来自 Mtb 等细菌病原体的配体，这对于肺部 MAIT 细胞早期识别感染细胞可能很重要。