T cell receptors (TCRs) recognize antigens presented by major histocompatibility complex (MHC) and MHC class I–like molecules. We describe a diverse population of human γδ T cells isolated from peripheral blood and tissues that exhibit autoreactivity to the monomorphic MHC-related protein 1 (MR1). The crystal structure of a γδTCR–MR1–antigen complex starkly contrasts with all other TCR–MHC and TCR–MHC-I-like complex structures. Namely, the γδTCR binds underneath the MR1 antigen-binding cleft, where contacts are dominated by the MR1 α3 domain. A similar pattern of reactivity was observed for diverse MR1-restricted γδTCRs from multiple individuals. Accordingly, we simultaneously report MR1 as a ligand for human γδ T cells and redefine the parameters for TCR recognition.

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In nonhuman primates, Vγ9Vδ2+ (Vδ2)T cells proliferate and accumulate in mucosal tissues following microbial activation. Human Vδ2T cells produce proinflammatory cytokines in response to bacterial species that colonize the gut, but the role played by Vδ2T cells in intestinal immunity is unknown. We hypothesized that circulating Vδ2T cells can populate the human intestine and contribute to mucosal inflammation. Cell suspensions prepared from peripheral blood and intestinal biopsies were stimulated with microbial phosphoantigen (1-hydroxy-2-methyl-2-buten-4-yl 4-diphosphate [HDMAPP]) and analyzed by flow cytometry to determine Vδ2T cell phenotype, cytokine production, and proliferative potential. Circulating Vδ2T cells expressed gut-homing integrin α4β7 (>70%), which was coexpressed with skin-associated cutaneous leukocyte Ag by up to 15% of the total population. However, Vδ2T cell activation with HDMAPP and exposure to retinoic acid (signaling via retinoic acid receptor α) increased α4β7 expression and enhanced binding to mucosal addressin cell adhesion molecule-1 in vitro while simultaneously suppressing cutaneous leukocyte Ag, thereby generating a committed gut-tropic phenotype. Confocal microscopy and flow cytometry identified frequent Vδ2T cells that migrated out of human intestinal biopsies and comprised both CD103+ and CD103− subsets that produced TNF-α and IFN-γ upon phosphoantigen exposure, with more frequent cytokine-producing cells in the CD103− population. Activated intestinal Vδ2T cells expressed CD70 and HLA-DR but were unable to drive the proliferation of allogeneic naive CD4+ T cells. Instead, phosphoantigen-activated CD103− Vδ2T cells increased T-bet expression and enhanced IFN-γ production by autologous colonic αβ T cells via an IFN-γ–dependent mechanism. These data demonstrate that circulating Vδ2T cells display enhanced gut-homing potential upon microbial activation and populate the human intestinal mucosa, generating functionally distinct CD103+ and CD103− subsets that can promote inflammation by colonic αβ T cells.

Big data has become a central part of medical research, as well as modern life generally. “Omics” technologies include genomics, proteomics, microbiomics and increasingly other omics. These have been driven by rapid advances in laboratory techniques and equipment. Crucially, improved information handling capabilities have allowed concepts such as artificial intelligence and machine learning to enter the research world. The COVID‐19 pandemic has shown how quickly information can be generated and analyzed using such approaches, but also showed its limitations. This review will look at how “omics” has begun to be translated into clinical practice. While there appears almost limitless potential in using big data for “precision” or “personalized” medicine, the reality is that this remains largely aspirational. Oncology is the only field of medicine that is widely adopting such technologies, and even in this field uptake is irregular. There are practical and ethical reasons for this lack of translation of increasingly affordable techniques into the clinic. Undoubtedly, there will be increasing use of large data sets from traditional (e.g. tumor samples, patient genomics) and nontraditional (e.g. smartphone) sources. It is perhaps the greatest challenge of the health‐care sector over the coming decade to integrate these resources in an effective, practical and ethical way.