γδ T cells are a unique and conserved population of lymphocytes that have been the subject of a recent explosion of interest owing to their essential contributions to many types of immune response and immunopathology. But what does the integration of recent and long-established studies really tell us about these cells and their place in immunology? The time is ripe to consider the evidence for their unique and crucial functions. We conclude that whereas B cells and αβ T cells are commonly thought to contribute primarily to the antigen-specific effector and memory phases of immunity, γδ T cells are distinct in that they combine conventional adaptive features (inherent in their T cell receptors and pleiotropic effector functions) with rapid, innate-like responses that can place them in the initiation phase of immune reactions. This underpins a revised perspective on lymphocyte biology and the regulation of immunogenicity.

Summary To gain further insight into the genetic architecture of psoriasis, we conducted a meta-analysis of three genome-wide association studies (GWAS) and two independent datasets genotyped on the Immunochip, involving 10,588 cases and 22,806 controls in total. We identified 15 new disease susceptibility regions, increasing the number of psoriasis-associated loci to 36 for Caucasians. Conditional analyses identified five independent signals within previously known loci. The newly identified shared disease regions encompassed a number of genes whose products regulate T-cell function (e.g. RUNX3, TAGAP and STAT3). The new psoriasis-specific regions were notable for candidate genes whose products are involved in innate host defense, encoding proteins with roles in interferon-mediated antiviral responses (DDX58), macrophage activation (ZC3H12C), and NF-κB signaling (CARD14 and CARM1). These results portend a better understanding of shared and distinctive genetic determinants of immune-mediated inflammatory disorders and emphasize the importance of the skin in innate and acquired host defense.