Enrichment of a CD4 ^- CD8 ^- NK-like cytotoxic Vδ1/3 T cell subset in tuberculosis disease

Tuberculosis (TB), caused by Mycobacterium tuberculosis , remains a leading cause of global morbidity and mortality. Although gamma-delta (γδ) T cells have increasingly been suggested to contribute to the TB immune response, quantitative and qualitative differences in this immune cell compartment between healthy and TB diseased individuals are not well-characterized. In this study, we used single-cell RNA sequencing to provide a high-resolution characterization of CD4 ^- CD8 ^- γδ T cells in peripheral blood across healthy Mtb -non-sensitized, healthy Mtb -sensitized, and TB disease pre-/post-treatment cohorts. We found upregulation of an activated and cytotoxic gene signature in γδ T cells of TB disease compared to both healthy cohorts. Strikingly, these differences persisted through one year following diagnosis of TB disease (corresponding to six months after completion of anti-TB therapy). We found that these transcriptomic differences were largely mediated by an NK-like cytotoxic Vδ1 and Vδ3 subset that was enriched in TB disease, with a unique Vδ3 TCR gene usage. Our findings suggest long-lasting changes in the CD4 ^- CD8 ^- γδ T cell compartment and highlight Vδ3 cells, a previously underappreciated γδ T cell subset, as potentially important in TB.