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HLA (HLA) are a major barrier to transplant success, as HLA‐A and ‐B molecules are principal ligands for T‐cells, and HLA‐C for Killer cell Immunoglobulin‐like Receptors (KIR), directing Natural Killer (NK) cell function. HLA‐C molecules are designated "C1" or "C2" ligands based on residues 77 and 80, which determine the NK cell responses. Here, we investigated donor/recipient HLA‐C mismatch associations with the development of chronic lung allograft dysfunction (CLAD) following lung transplantation (LTx). 310 LTx donor/recipient pairs were Next Generation Sequenced and assessed for C1 and C2 allotypes. PIRCHE scores were used to quantify HLA mismatching between donor/recipients at amino acid level and stratify recipients into low, moderate or highly mismatched groups (n = 103–104). Associations between C ligands and freedom from CLAD was assessed with Cox regression models and survival curves. C2/C2 recipients (n = 42) had less CLAD than those with C1/C1 (n = 138) or C1/C2 genotypes (n = 130) (p < 0.05). Incidence of CLAD was lower in C2/C2 recipients receiving a mismatched C1/C1 allograft (n = 14), compared to matched (n = 8) or heterozygous (n = 20) allografts. Furthermore, ~80% of these recipients (C2/C2 recipients receiving C1/C1 transplants) remained CLAD‐free for 10 years post‐LTx. Recipients with higher HLA‐C mismatching had less CLAD (p < 0.05) an observation not explained by linkage disequilibrium with other HLA loci. Our data implicates a role for HLA‐C in CLAD development. HLA‐C mismatching was not detrimental to LTx outcome, but potentially beneficial, representing a paradigm shift in assessing donor/recipient matching. This may inform better selection of donor/recipient pairs and potentially more targeted approaches to treating CLAD. [ABSTRACT FROM AUTHOR]

HLA-B*57 control of HIV involves enhanced CD8+ T cell responses against infected cells, but extensive heterogeneity exists in the level of HIV control among B*57+ individuals. Using whole-genome sequencing of untreated B*57+ HIV-1-infected controllers and noncontrollers, we identified a single variant (rs643347A/G) encoding an isoleucine-to-valine substitution at position 47 (I47V) of the inhibitory killer cell immunoglobulin-like receptor KIR3DL1 as the only significant modifier of B*57 protection. The association was replicated in an independent cohort and across multiple outcomes. The modifying effect of I47V was confined to B*57:01 and was not observed for the closely related B*57:03. Positions 2, 47, and 54 tracked one another nearly perfectly, and 2 KIR3DL1 allotypes differing only at these 3 positions showed significant differences in binding B*57:01 tetramers, whereas the protective allotype showed lower binding. Thus, variation in an immune NK cell receptor that binds B*57:01 modifies its protection. These data highlight the exquisite specificity of KIR-HLA interactions in human health and disease.

The heterodimeric natural killer cells antigen CD94 (CD94)–NKG2‐A/NKG2‐B type II integral membrane protein (NKG2A) receptor family expressed on human and mouse natural killer (NK) cells monitors global major histocompatibility complex (MHC) class I cell surface expression levels through binding to MHC class Ia‐derived leader sequence peptides presented by HLA class I histocompatibility antigen, alpha chain E (HLA‐E; in humans) or H‐2 class I histocompatibility antigen, D‐37 (Qa‐1b; in mice). Although the molecular basis underpinning human CD94–NKG2A recognition of HLA‐E is known, the equivalent interaction in the murine setting is not. By determining the high‐resolution crystal structure of murine CD94–NKG2A in complex with Qa‐1b presenting the Qa‐1 determinant modifier peptide (QDM), we resolved the mode of binding. Compared to the human homologue, the murine CD94–NKG2A–Qa‐1b–QDM displayed alterations in the distribution of interactions across CD94 and NKG2A subunits that coincide with differences in electrostatic complementarity of the ternary complex and the lack of cross‐species reactivity. Nevertheless, we show that Qa‐1b could be modified through W65R + N73I mutations to mimic HLA‐E, facilitating binding with both human and murine CD94–NKG2A. These data underscore human and murine CD94–NKG2A cross‐species heterogeneity and provide a foundation for humanising Qa‐1b in immune system models. [ABSTRACT FROM AUTHOR]

The article reports that the host biomarkers help diagnose tuberculosis (TB) state or correlates of protection against active disease and also direct the response to therapy. Topics include examines specific CD81 memory T cells can be considered both correlates of protective immunity and potential biomarkers of infectious diseases, such as TB, particularly when there is a need to distinguish active TB fromlatent TB infection.

Members of the killer cell immunoglobulin-like receptor (KIR) family, a large group of polymorphic receptors expressed on natural killer (NK) cells, recognize particular peptide-laden human leukocyte antigen (pHLA) class I molecules and have a pivotal role in innate immune responses (1). Allelic variation and extensive polymorphism within the three-domain KIR family (KIR3D, domains D0-D1-D2) affects pHLA binding specificity and is linked to the control of viral replication and the treatment outcome of certain haematological malignancies (1-3). Here we describe the structure of a human KIR3DL1 receptor bound to HLA-B*5701 complexed with a self-peptide. KIR3DL1 clamped around the carboxy-terminal end of the HLA-B*5701 antigen-binding cleft, resulting in two discontinuous footprints on the pHLA. First, the D0 domain, a distinguishing feature of the KIR3D family, extended towards β2-microglobulin and abutted a region of the HLA molecule with limited polymorphism, thereby acting as an 'innate HLA sensor' domain. Second, whereas the D2-HLA-B*5701 interface exhibited a high degree of complementarity, the D1-pHLA-B*5701 contacts were suboptimal and accommodated a degree of sequence variation both within the peptide and the polymorphic region of the HLA molecule. Although the two-domain KIR (KIR2D) and KIR3DL1 docked similarly onto HLA-C (4,5) and HLA-B respectively, the corresponding Dl-mediated interactions differed markedly, thereby providing insight into the specificity of KIR3DL1 for discrete HLA-A and HLA-B allotypes. Collectively, in association with extensive mutagenesis studies at the KIR3DL1-pHLA-B*5701 interface, we provide a framework for understanding the intricate interplay between peptide variability, KIR3D and HLA polymorphism in determining the specificity requirements of this essential innate interaction that is conserved across primate species., HLA-B57 carriage has been associated with delayed progression to AIDS in HIV-infected individuals, with a strong genetic association between the KIR3DL1-HLA-B57 interaction, reduced viral loads and delayed HIV disease progression [...]

Infections localized to peripheral tissues such as the skin result in the priming of T-cell responses that act to control pathogens. Activated T cells undergo migrational imprinting within the draining lymph nodes (1), resulting in memory T cells that provide local and systemic protection (2). Combinations of migrating and resident memory T cells have been implicated in long-term peripheral immunity, especially at the surfaces that form pathogen entry points into the body (3). However, T-cell immunity consists of separate [CD4.sup.+] helper T cells and [CD8.sup.+] killer T cells, with distinct effector and memory programming requirements (4). Whether these subsets also differ in their ability to form a migrating pool involved in peripheral immunosurveillance or a separate resident population responsible for local infection control has not been explored. Here, using mice, we show key differences in the migration and tissue localization of memory [CD4.sup.+] and [CD8.sup.+] T cells following infection of the skin by herpes simplex virus. On resolution of infection, the skin contained two distinct virus-specific memory subsets; a slow-moving population of sequestered [CD8.sup.+] T cells that were resident in the epidermis and confined largely to the original site of infection, and a dynamic population of [CD4.sup.+] T cells that trafficked rapidly through the dermis as part of a wider recirculation pattern. Unique homing-molecule expression by recirculating [CD4.sup.+] T effector-memory cells mirrored their preferential skin-migratory capacity. Overall, these results identify a complexity in memory T-cell migration, illuminating previously unappreciated differences between the [CD4.sup.+] and [CD8.sup.+] subsets., Intravital microscopy has provided novel insights into the migration of naive and effector T cells in lymphoid and non-lymphoid compartments, although there has been no concurrent investigation of [CD4.sup.+] and [...]