TRAV1-2+ CD8+ T-cells including oligoconal expansions of MAIT cells are enriched in the airways in human tuberculosis

Mucosal-associated invariant T (MAIT) cells typically express a TRAV1-2 + semi-invariant TCRα that enables recognition of bacterial, mycobacterial, and fungal riboflavin metabolites presented by MR1. MAIT cells are associated with immune control of bacterial and mycobacterial infections in murine models. Here, we report that a population of pro-inflammatory TRAV1-2 + CD8 + T cells are present in the airways and lungs of healthy individuals and are enriched in bronchoalveolar fluid of patients with active pulmonary tuberculosis (TB). High-throughput T cell receptor analysis reveals oligoclonal expansions of canonical and donor-unique TRAV1-2 + MAIT-consistent TCRα sequences within this population. Some of these cells demonstrate MR1-restricted mycobacterial reactivity and phenotypes suggestive of MAIT cell identity. These findings demonstrate enrichment of TRAV1-2 + CD8 + T cells with MAIT or MAIT-like features in the airways during active TB and suggest a role for these cells in the human pulmonary immune response to Mycobacterium tuberculosis . Emily Wong et al. observe that Mycobacterium tuberculosis (Mtb) infection induces recruitment and expansion of a CD8 + TRAV1-2 + T-cell population in the airways of human patients. T cell receptor analysis showed expansion of this cell population, including oligoclonal MAIT cells, in sites where Mtb antigens are present, suggesting they act as sentinels of pulmonary infection.