cPRA Increases With DQA,DPA, and DPB Unacceptable Antigens in the Canadian cPRA Calculator

A calculated panel reactive antibody (cPRA) estimates the percentage of donors with unacceptable antigens (UA) for a recipient. cPRA may be underestimated in transplant candidates with UA to DQA, DPA, and DPB if these are not included in the calculation program. To serve the National Canadian Transplant Programs, a cPRA calculator was developed with complete molecular typing for all donors at HLA‐A, B, C, DRB1, DRB3/4/5, DQA1, DQB1, DPA1, and DPB1, all resolved to serologic equivalents. The prevalence of UA at DQA, DPA and DPB was evaluated in a sensitized regional population. The impact of adding these additional UA to cPRA was calculated alone and in combination, and compared to the baseline cPRA for UA at A, B, C, DR, DR51/52/53, and DQ. Of 740 sensitized transplant candidates, 18% of total and 32% with cPRA≥95% had DQA UA. Twenty‐seven percent of total and 54% with cPRA≥95% had DPB UA. Of 280/740 subjects with these UA, 36/280 (13%) had cPRA increase of >20% when they were included, 7% increased cPRA to ≥80% and 6% to ≥95%. Inclusion of DQA, DPA, and DPB UA in Canadian cPRA calculations improves the accuracy of cPRA where these are relevant in allocation.     

HLA class II allele polymorphism in an outbreak of chikungunya fever in Middle Andaman,India

A sudden upsurge of fever cases with joint pain was observed in the outpatient department, Community Health Centre, Rangat during July–August 2010 in Rangat Middle Andaman, India. The aetiological agent responsible for the outbreak was identified as chikungunya virus (CHIKV), by using RT‐PCR and IgM ELISA. The study investigated the association of polymorphisms in the human leucocyte antigen class II genes with susceptibility or protection against CHIKV. One hundred and one patients with clinical features suggestive of CHIKV infection and 104 healthy subjects were included in the study. DNA was extracted and typed for HLA‐DRB1 and DQB1 alleles. Based on the amino acid sequences of HLA‐DQB1 retrieved from the IMGT/HLA database, critical amino acid differences in the specific peptide‐binding pockets of HLA‐DQB1 molecules were investigated. The frequencies of HLA‐DRB1 alleles were not significantly different, whereas lower frequency of HLA‐DQB1*03:03 was observed in CHIKV patients compared with the control population [P = 0·001, corrected P = 0·024; odds ratio (OR)  = 0, 95% confidence interval (95% CI) 0·0–0·331; Peto's OR = 0·1317, 95% CI 0·0428–0·405). Significantly lower frequency of glutamic acid at position 86 of peptide‐binding pocket 1 coding HLA‐DQB1 genotypes was observed in CHIKV patients compared with healthy controls (P = 0·004, OR = 0·307, 95% CI 0·125–0·707). Computational binding predictions of CD4 epitopes of CHIKV by NetMHCII revealed that HLA‐DQ molecules are known to bind more CHIKV peptides than HLA‐DRB1 molecules. The results suggest that HLA‐DQB1 alleles and critical amino acid differences in the peptide‐binding pockets of HLA‐DQB1 alleles might have role in influencing infection and pathogenesis of CHIKV.     

不同应激对小鼠免疫防御功能的影响及其与H2-Eb基因多态性的关系

探讨两种应激对小鼠免疫防御功能的影响及其与H2-Eb基因多态性的关系。制备束缚应激和热应激动物模型,以大肠埃希菌攻击小鼠,比较应激状态下小鼠与正常小鼠的死亡率;采用PCR技术检测以MudoEb5和MudoEb7为代表的小鼠H2-Eb位点等位基因的多态性,分析应激免疫与H2-Eb基因多态性的关系。结果发现小鼠染菌后束缚应激组和热应激组小鼠死亡率均显著高于对照组小鼠(P<0.005),束缚应激组和热应激组小鼠死亡率无明显差异(P>0.05)。正常对照组和束缚应激组小鼠MudoEb5基因型与小鼠接受细菌攻击后生存状态间均无明显相关性(P>0.05),热应激组小鼠MudoEb5基因型与小鼠接受细菌攻击后生存状态间存在明显相关性(P<0.05),三组小鼠MudoEb7基因型与小鼠接受细菌攻击后生存状态间均无明显相关性(P>0.05),MudoEb5和MudoEb7交互作用对各组小鼠染菌后生存状态均无明显影响(P>0.05)。可见束缚应激和热应激均可降低小鼠的免疫防御功能,MudoEb5可能与热应激条件下免疫防御功能降低程度有关。     

Variation in genes implicated in B‐cell development and antibody production affects susceptibility to pemphigus

Pemphigus foliaceus (PF) is an autoimmune blistering skin disease characterized by the presence of pathogenic autoantibodies against desmoglein 1, a component of intercellular desmosome junctions. PF occurs sporadically across the globe and is endemic in some Brazilian regions. Because PF is a B‐cell‐mediated disease, we aimed to study the impact of variants within genes encoding molecules involved in the different steps of B‐cell development and antibody production on the susceptibility of endemic PF. We analysed 3,336 single nucleotide polymorphisms (SNPs) from 167 candidate genes genotyped with Illumina microarray in a cohort of 227 PF patients and 193 controls. After quality control and exclusion of non‐informative and redundant SNPs, 607 variants in 149 genes remained in the logistic regression analysis, in which sex and ancestry were included as covariates. Our results revealed 10 SNPs within or nearby 11 genes that were associated with susceptibility to endemic PF (OR >1.56; p < 0.005): rs6657275*G (TGFB2); rs1818545*A (RAG1/RAG2/IFTAP);rs10781530*A (PAXX), rs10870140*G and rs10781522*A (TRAF2); rs535068*A (TNFRSF1B); rs324011*A (STAT6);rs6432018*C (YWHAQ); rs17149161*C (YWHAG); and rs2070729*C (IRF1). Interestingly, these SNPs have been previously associated with differential gene expression, mostly in peripheral blood, in publicly available databases. For the first time, we show that polymorphisms in genes involved in B‐cell development and antibody production confer differential susceptibility to endemic PF, and therefore are candidates for possible functional studies to understand immunoglobulin gene rearrangement and its impact on diseases.     

Major histocompatibility complex class II (DRB1*, DQA1*, and DQB1*) and DRB1*04 subtypes' associations of Hashimoto's thyroiditis in a Greek population

Hashimoto's thyroiditis (HT) is an autoimmune disease resulting from complex interactions between genetic and environmental factors. The disease is associated with certain human leukocyte antigen (HLA) class II alleles in various populations. We aimed to determine in this study, for the first time in a Greek population, the association of HLA-DRB1*, -DQA1*, and -DQB1* alleles with HT. HLA-DRB1*, -DQA1*, and -DQB1* alleles' and -DRB1*04 subtypes' distribution was evaluated in 125 patients with HT and in 500 healthy control individuals by using a DNA-based sequence-specific primer method. Chi^_squared tests and Bonferroni correction method were applied in the statistical analysis of the data. Significantly higher frequency of DRB1*04 (24.8% vs 7.7%, P  < 0.0001) was observed in HT patients, while HLA-DRB1*07 was significantly decreased (2.8% vs 7.9%, P  < 0.05). HLA-DRB1*04 subtyping showed a significant increase of DRB1*0405 (21% vs 7.8%, P  < 0.0001) in HT patients. Also significant high frequencies of DQB1*0201 (14.8% vs 8.2%, P  < 0.001), DQB1*0302 (18.8% vs 7.0%, P  < 0.0001), and DQA1*0301 (25.6% vs 7.8%, P  < 0.0001) were recorded in the patient group. Conducting the first research of this kind in a Greek population, our study tries to provide an evaluation of the prevalence of HT relating to HLA-DRB1*0405, and we report a relative risk of 2.7 for HT in a Greek population.     

Identification of the first Toll-like receptor gene in passerine birds: TLR4 orthologue in zebra finch (Taeniopygia guttata)

Toll-like receptors (TLRs) are the basic components of the vertebrate pathogen recognition system. Despite uniform general structure, remarkable variability in domain composition can be found in individual TLRs among species. Knowledge of interspecific differences is of particular importance to our understanding of selective pressures on TLRs. Currently, most TLRs are characterized only in a limited number of model species, including domestic chicken as a universal avian model. Here, we describe structure and expression pattern of TLR4 in zebra finch, a widely used passerine model species. The tgTlr4 gene consists of three exons (204, 167 and 3033–3043 bp) that are transcribed into messenger RNA with a relatively long 3'-untranslated region (788 bp). Predicted protein is composed of 842 amino acids (aas) forming extracellular domain with nine leucine-rich repeat (LRR) motives flanked at the carboxy-terminal end by leucine-rich repeat carboxy-terminal domain, transmembrane domain and cytoplasmic toll/interleukin-1 receptor domain. The overall structure is similar to other known TLR4 molecules with 32%–49% aa identity to various mammals and 74% to chicken. Although the position of most of the domains in zebra finch TLR4 resembles their position in chicken, there is one extra LRR at the aa position 207–229 in tgTLR4 and one LRR known in chTLR4 is missing. The gene is highly expressed in the bone marrow and in the spleen, intermediately in the gut and low expression was found in the liver and lungs. For the first time in birds, expression of tgTLR4 in peritoneal macrophages was found to be enhanced by the Escherichia coli lipopolysaccharide treatment.     

Lipoprotein immunogenetics and atherosclerosis

The discovery of the first human lipoprotein polymorphism by Allison and Blumberg [Lancet i:634-637, 1961] and the availability of alloimmune sera stimulated us to begin immunogenetic studies on swine in search of lipoprotein diversity and its relationship to biological functions. We found considerable lipoprotein polymorphism, complexity, and heterogeneity in this species. These results and the correlation between immunogenetically defined lipoprotein type and arterial lipidosis in swine, fed a high fat diet, are discussed. Immunogenetic studies of lipoproteins, initiated more recently in rhesus monkeys, will be reviewed also. Preliminary data show similarities between these two species with regard to polymorphism, complexity, phenotypic expression of lipoprotein genes and, most importantly, their serological relationship to human lipoproteins. We also note immunogenetic studies on lipoproteins done by other investigators, or in other species. Brief remarks on implications of the lipoproteins in atherosclerosis, their general classification, immunological properties, and immunological methods used in their study precede the immunogenetic presentation.