复发性阿弗它口炎与MHC-DR基因遗传多态性研究

目的：探讨复发性阿弗它口炎（RAS）易感的分子免疫遗传学机制和确立一种较为实用的MHC-Ⅱ类基因检测方法。方法：采用聚合酶链式反应和顺序特异性引物（PCR-SSP）基因分析法,对31例复发性阿弗它口炎患者及30例无血缘关系的健康人的人类主要组织相容性复合体（MHC-Ⅱ类）DR各等位基因及亚基因进行检测分析,并将该方法与其它检测MHC-Ⅱ类基因的方法进行对比。结果：结果表明,MHC-DRB1＊0301基因与RAS呈正相关（RR=4．696,P〈0．05）,其它MHC-DRB1＊各等位基因未见异常。结论：MHC-DRB1＊0301基因可能是北方汉族人RAS的致病易感基因之一。本文所采用的方法（PCR-SSP法）具有快速、简便、敏感、准确和可靠等优点。     

A blueprint for electronic utilization of ambiguous molecular HLA typing data in organ allocation systems and virtual crossmatch

Virtual crossmatch (VXM) compares a transplant candidate’s unacceptable antigens to the HLA typing of the donor before an organ offer is accepted and, in selected cases, supplant a prospective physical crossmatch. However, deceased donor typing can be ambiguous, leading to uncertainty in compatibility prediction. We have developed a prototype web application that utilizes ambiguous HLA molecular typing data to predict which unacceptable antigens are present in the donor HLA genotype as donor-specific antibodies (DSA). The application compares a candidate’s listed unacceptable antigens to computed probabilities of all possible two-field donor HLA alleles and UNOS antigens. The VIrtual CrossmaTch for mOleculaR HLA typing (VICTOR) tool can be accessed at http://www.transplanttoolbox.org/victor. We reanalyzed historical VXM cases where a transplant center’s manual interpretation of molecular typing results influenced offer evaluation. We found that interpretation of ambiguous donor molecular typing data using imputation could one day influence VXM decisions if the DSA predictions were rigorously validated. Standardized interpretation of molecular typing data, if applied to the match run, could also change which offers are made. HLA typing ambiguity has been an underappreciated source of immunological risk in organ transplantation. The VICTOR tool can serve as a testbed for development of allocation policies with the aim of decreasing offers refused due to HLA incompatibility.     

Infection with a virus generates a polyclonal immune response with broad alloreactive potential

Virus-specific T cells have been shown to cross-react with allogeneic HLA (allo-HLA) at a clonal level. However, the impact of a single virus on the allorepertoire has never been investigated at the polyclonal level.We made an inventory of the incidence and specificity of allo-HLA-cross-reactive-virus-specific CD8⁺ T cells in 24 healthy individuals. T cells were stained for 25 virus-specific tetramers, and mixed-lymphocyte reactions were performed against a panel of HLA-typed allostimulators. Allospecificity was confirmed by IFNγ-ELISA using T-cell clones against a panel of HLA-typed cell-lines.The polyclonal immune repertoire directed against CMV alone was associated with a memory response against six allo-HLA molecules. Besides, a single allostimulator activated memory T-cell responses with multiple viral specificities.Concluding, a single virus can substantially broaden the allo-HLA memory T-cell repertoire. This study only looked at CMV- and EBV-specific T cells, whereas the immune repertoire consists of T cells directed against many different viruses. Hence, transplant patients receiving an HLA-mismatched graft may already express a polyclonal repertoire of anti-donor-memory T cells before transplantation.     

Acute Antibody-Mediated Rejection by De Novo Anti-HLA-DPβ and -DPα Antibodies After Kidney Transplantation: A Case Report

The presence of isolated de novo anti-DP antibodies is uncommon, making it difficult to determine the impact of anti-DP antibodies on graft outcome. We describe a case of acute antibody-mediated rejection mediated by de novo donor-specific anti-HLA-DP antibodies. Furthermore, the generation of non–donor-specific anti-DP antibodies (NDSAs) detected in the patient's sera was investigated. An 18-year-old woman with pretransplant 0% panel-reactive antibody received kidney transplantation from a living donor. She experienced combined acute T-cell-mediated and antibody-mediated rejection at 15 months after transplantation. High resolution HLA typing of the donor and the patient revealed that they were mismatched at both DPB1 (DPB1*31:01) and DPA1 (DPA1*02:02) loci. The single antigen bead (SAB) testing of patient's sera revealed antibodies against donor's DPB1*31:01 and DPA1*02:02 alleles. Antibodies against several non–donor-specific DP antigens were also detected. No antibodies against other HLA class I and II antigens were detected. In order to explain the reactivity pattern of NDSAs, HLAMatchmaker program was used to identify immunizing eplets shared between donor alleles and reactive beads. The analysis showed 84DEAV, a DPB1 eplet, as a shared eplet found on DPB1*31:01 (mismatched donor allele) and on DPB1-reactive alleles in SAB assay. Additionally, 50RA, a DPA1 eplet, was identified as a shared eplet found on DPA1*02:02 (mismatched donor allele) and on DPA1-reactive alleles in SAB assay. This case highlights the clinical significance of HLA-DP antibodies. Furthermore, the generation of NDSA anti-DP antibodies by epitope sharing underscores the importance of HLA-DP epitope matching in kidney transplantation.     

Collection and storage of HLA NGS genotyping data for the 17th International HLA and Immunogenetics Workshop

For over 50?years, the International HLA and Immunogenetics Workshops (IHIW) have advanced the fields of histocompatibility and immunogenetics (H&I) via community sharing of technology, experience and reagents, and the establishment of ongoing collaborative projects. Held in the fall of 2017, the 17th IHIW focused on the application of next generation sequencing (NGS) technologies for clinical and research goals in the H&I fields. NGS technologies have the potential to allow dramatic insights and advances in these fields, but the scope and sheer quantity of data associated with NGS raise challenges for their analysis, collection, exchange and storage. The 17th IHIW adopted a centralized approach to these issues, and we developed the tools, services and systems to create an effective system for capturing and managing these NGS data. We worked with NGS platform and software developers to define a set of distinct but equivalent NGS typing reports that record NGS data in a uniform fashion. The 17th IHIW database applied our standards, tools and services to collect, validate and store those structured, multi-platform data in an automated fashion. We have created community resources to enable exploration of the vast store of curated sequence and allele-name data in the IPD-IMGT/HLA Database, with the goal of creating a long-term community resource that integrates these curated data with new NGS sequence and polymorphism data, for advanced analyses and applications.     

Association of HLA-E*01:01/*01:03 polymorphism with methotrexate-based treatment response in South Indian rheumatoid arthritis patients

ObjectivesNon-classical HLA-E molecules may influence the disease susceptibility and phenotype including treatment response in chronic inflammatory disorders such as Rheumatoid Arthritis (RA) by virtue of their capacity to modulate innate immune processes. This study was carried out to investigate the role of HLA-E polymorphism in RA susceptibility, clinical and serological phenotype as well as treatment response.MethodsGenomic DNA from 221 RA patients and 200 healthy controls (HC) were typed for HLA-E rs2844724 (C/T) and rs1264457 (HLA-E*01:01/*01:03) single nucleotide polymorphisms (SNPs) using the TaqMan 5'nuclease assay consisting of allele-specific fluorogenic oligonucleotide probes.ResultsOur study did not find any association between HLA-E polymorphism and RA susceptibility or disease phenotype. However, it was observed that the frequency of HLA-E*01:03 allele was higher in all RA cases (Pc = 0.03, OR = 3.02, 95% CI = 1.06–9.39), young onset RA (YORA) (Pc = 0.03, OR = 3.20, 95% CI = 1.11–9.98) and female RA (Pc = 0.04, OR = 3.04, 95% CI = 1.06–9.46) patients who responded well (good responders) to a combination of non-biological disease modifying anti rheumatic drugs (DMARDs), methotrexate (MTX) and hydroxychloroquine (HCQ) as compared to non-responders. Moreover, the frequency of rs2844724 T allele and TT genotype was observed to be higher in patients with low titers of rheumatoid factor (RF) than those with high titers (90% vs. 77% and 79% vs. 59% respectively), although the difference did not reach statistical significance.ConclusionThe results of our study suggest that HLA-E rs1264457 may influence the patient response to treatment with methotrexate-based DMARD therapy. Thus, it may be a useful genetic marker for treatment response in patients with RA.     

Review: Pathogenesis of cholestatic liver diseases

Cholestatic liver diseases (CLD) begin to develop after an impairment of bile flow start to affect the biliary tree. Cholangiocytes actively participate in the liver response to injury and repair and the intensity of this reaction is a determinant factor for the development of CLD. Progressive cholangiopathies may ultimately lead to end-stage liver disease requiring at the end orthotopic liver transplantation. This narrative review will discuss cholangiocyte biology and pathogenesis mechanisms involved in four intrahepatic CLD: Primary biliary cholangitis, primary sclerosing cholangitis, cystic fibrosis involving the liver, and polycystic liver disease.     

Etiopathogenesis of primary sclerosing cholangitis

Primary sclerosing cholangitis（PSC） is a chronic cholestatic liver disease of unknown etiology but lymphocytic portal tract infiltration is suggestive of an immune-mediated basis for this disease.Associations with inflammatory bowel disease（IBD） especially ulcerative colitis（UC）,and with particular autoimmune diseases,as well as the genetic associations further suggest PSC may be an immune-mediated disease.The immunogenetics of PSC have been the subject of active research and several HLA and non-HLA associated genes have been implicated in the development of the disease.Lymphocytes derived from the inflamed gut may enter the liver via the enterohepatic circulation to cause hepatic disease.PSC may be triggered in genetically susceptible individuals by infections or toxins entering the portal circulation through a permeable colon and hence evoking an abnormal immune response.     

MHC class II sequences of susceptibility and protection in Mexicans with autoimmune hepatitis

Background/Aims: Autoimmune hepatitis has a genetic background associated with different HLA DRB1 alleles depending on the ethnic group. The aim of this study was to analyse the immunogenetics of type I autoimmune hepatitis in Mexicans.Methods: Thirty Mexican Mestizo patients and 175 healthy controls were HLA typed as follows: class I antigens were determined by microlymphocytotoxicity and class II typing was done on DNA samples using PCR-SSO and PCR-SSP for DRB1, DQA1 and DQB1 loci.Results: A significant association of autoimmune hepatitis with DRB1*0404 was found, (χ²Y=19.95, pc=0.002, RR=7.71), suggesting the presence of a susceptibility gene located at the DRB1 locus. Resistance was at least partially due to a DQB1 gene, since a significant decrease in DQB1*0301 was also detected (χ²Y=8.21, pc=0.04). Analysis of subgroups according to age at onset showed an association with DBR1*0404 (χ²Y=4.31, p=0.04) in patients with late onset (after 30 years), while DQA1*0501 (χ²Y=5.12, p=0.02) was increased in the early onset group.Conclusions: The possible mechanism of HLA association is due to “shared epitopes”, since DRB1*0404, and those found in other populatios namely, DRB1*0401, *0405 and *0301 share almost the same sequence at position 67–72 (LLEQRR, R or K at 71). Valine-86 is also relevant to the age at onset because DRB1*0404 is increased in the patients with an average age at onset of 32. These findigs are relevant in determining which peptides in the liver are targets for T cells.