HLA-DP Alleles Research Articles

Principal contribution of HLA-DQ alleles, DQB1*06:04 and DQB1*03:01, to disease resistance against primary biliary cholangitis in a Japanese population

Identification of the primary allele(s) in HLA class II associated diseases remains challenging because of a tight linkage between alleles of HLA-DR and -DQ loci. In the present study, we determined the genotypes of seven HLA loci (HLA-A, -B, -DRB1, -DQA1, -DQB1, -DPA1 and -DPB1) for 1200 Japanese patients with primary biliary cholangitis and 1196 controls. Observation of recombination derivatives facilitated an evaluation of the effects of individual HLA alleles consisting of disease-prone/disease-resistant HLA haplotypes. Consequently, a primary contribution of DQB1*06:04 (odds ratio: 0.19, p = 1.91 × 10−22), DQB1*03:01 (odds ratio: 0.50, p = 6.76 × 10−10), DRB1*08:03 (odds ratio: 1.75, p = 1.01 × 10−7) and DQB1*04:01 (odds ratio: 1.50, p = 9.20 × 10−6) was suggested. Epistasis of the protective DQB1*06:04 to risk conferred by DRB1*08:03 was demonstrated by subpopulation analysis, implicating the presence of an active immunological mechanism that alleviates pathogenic autoimmune reactions. Further, the contribution of the aforementioned HLA alleles as well as an HLA-DP allele, DPB1*02:01 to the association signals of 304 loci among 4103 SNPs in the HLA region at the genome-wide level of significance (p values less than 5 × 10−8) was demonstrated by the stepwise exclusion of the individuals possessing these HLA alleles from the comparison.

Excavating the surface-associated and secretory proteome ofMycobacterium lepraefor identifying vaccines and diagnostic markers relevant immunodominant epitopes

For centuries, Mycobacterium leprae, etiological agent of leprosy, has been afflicting mankind regardless of extensive use of live-attenuated vaccines and antibiotics. Surface-associated and secretory proteins (SASPs) are attractive targets against bacteria. We have integrated biological knowledge with computational approaches and present a proteome-wide identification of SASPs. We also performed computational assignment of immunodominant epitopes as coordinates of prospective antigenic candidates in most important class of SASPs, the outer membrane proteins (OMPs). Exploiting the known protein sequence and structural characteristics shared by the SASPs from bacteria, 17 lipoproteins, 11 secretory and 19 novel OMPs (including 4 essential proteins) were identified in M. leprae As OMPs represent the most exposed antigens on the cell surface, their immunoinformatics analysis showed that the identified 19 OMPs harbor T-cell MHC class I epitopes and class II epitopes against HLA-DR alleles (54), while 15 OMPs present potential T-cell class II epitopes against HLA-DQ alleles (6) and 7 OMPs possess T-cell class II epitopes against HLA-DP alleles (5) of humans. Additionally, 11 M. leprae OMPs were found to have B-cell epitopes and these may be considered as prime candidates for the development of new immunotherapeutics against M. leprae.

P062 Evaluation of HLA-DP T-cell epitope (TCE) matching algorithm for selecting donors BMT/HSCT

Objective To determine the clinical validity of determining permissible or non-permissible HLA-DP Mismatch in the graft vs host direction and host vs graft direction for DP Mismatched BMT/HSCT. Methods The HLA-DP permissiveness is based on the TCE (T cell epitope) into 3 groups based on their immunogenicity or the cross reactivity of T cells allo-reactive to the HLA-DP allele as to: highly immunogenic; moderately immunogenic; and low immunogenicity [DPB1 T-Cell Epitope Algorithm v2.0 (2015–04)]. A retrospective study of 31 patients who underwent BMT/HSCT from a related or unrelated donor with whom they had a DP mismatch was done. High resolution typing by Sequence based typing was used to determine the DP alleles of the recipient and donor. The data was compiled and using the algorithm, the expected outcome was determined. The expected outcome was then compared with the clinical outcome. The results were analyzed under the following potential outcomes- transplant related mortality, GVHD, HVGD and relapse. Results Out of the 31 patients studied, the algorithm classified 15 pairs to be permissive (DP-P) and 16 non permissive (DP-NP). In the DP-NP transplants, 9 out of 16 patients were expected to develop aGVHD and 7/16 was expected to develop HVGD. In reality, 2 died due to TRM. Of the remaining 14, 6 developed GVHD and 6 developed HVHD, and 2 (15%) had relapse. In the DP-P transplants, the expected outcome was 0% TRM, 0%GVHD and, 0% HVGD. However, 2/15 (13%) died due to TRM, 7/13 (54%) developed aGVHD, 2/13 (15%) developed an HVGD with an average engraftment of 91%. The severity of aGVHD was less compared to what was observed in Non-Permissive mismatch. Among the 13 patients, 8 (61%) had relapse. Conclusions With this very limited analysis, it appears that the DP Mismatch Algorithm based on TCE seems to hold true regarding DP-NP mismatch. The DP-P mismatches had high relapse, and less severe aGVHD compared to DP-NP. The algorithm is worth exploring and we need more multi center retrospective and prospective evaluations. Ref.: Crivello P, et al. Transplantation Biol Blood Marrow Transplant (2015) 21:233–41.

Negatively-charged amino acids at the peptide-binding pocket of HLA-DPB1 alleles are associated with susceptibility to anti-topoisomerase I-positive systemic sclerosis

We investigated shared characteristics of amino acid sequences in the at risk HLA-DPB1 alleles in systemic sclerosis (SSc). Amino acid sequences and their structural features of HLA-DP molecules in 127 Korean SSc patients and 548 healthy Korean controls were analyzed with a focus on known HLA-DP binding motifs. The binding grooves containing more negatively-charged triplets (NCT) had higher odds ratios of anti-topoisomerase I antibody (ATA)-positive SSc. In particular, the co-existence of a NCT at position 82–85 and more than one additional NCT were critical for increased risk of ATA-positive SSc. Molecular dynamic simulations showed that the model peptide with positive charge from topoisomerase I fits more closely into HLA-DP alleles possessing more NCTs. ATA-positive SSc patients share NCTs at the peptide-binding groove of HLA-DPB1 molecules.

A large scale screening of HLA-class II-binding peptides from HBs and HBc peptide libraries

Abstract Objectives Variations in the human leukocyte antigens (HLA)-DP are associated strongly with susceptibility/protection to chronic hepatitis B virus (HBV) infection. It has been reported previously that HLA-DPB1*05:01 and *09:01, the major HLA-DP alleles in East Asians, are associated with susceptibility, while HLA-DPB1*04:01 and *04:02, the major alleles in Europeans, confer protection against chronic hepatitis B (Kamatani, et al. Nat Genet (2009); Nishida, et al. PLoS One (2012)). To identify the peptides that are potentially involved in immunological responses against HBV infection, we screened the peptide libraries of the HBV surface antigen (HBs) and core antigen (HBc) through the cell-surface HLA expression assay. Methods The six major HLA-DP haplotypes that are associated with susceptibility to or protection against chronic hepatitis B were used in this study. Peptide libraries were designed for the entire HBs and HBc antigens, based on the consensus sequence of the genotype C. To identify the HLA-DP-binding region, we expressed HLA-DP in fusion with each peptide, using fibroblast cell line as an expression host. Result The level of HLA-peptide interaction was estimated by measuring the level of cell-surface expression of each HLA-peptide fusion construct. Out of >70 peptides that cover the entire HBs and HBc antigens, we found several regions that bound strongly to certain HLA-DP allele products. In this presentation we show an overview of the methodology and discuss potential mechanisms that might underlie association of HLA-DP with chronic hepatitis B.

Effects of HLA-DPB1 genotypes on chronic hepatitis B infection in Japanese individuals.

Significant associations of HLA-DP alleles with chronic hepatitis B (CHB) infection are evident in Asian and Arabian populations, including Japanese, Han Chinese, Korean, and Saudi Arabian populations. Here, significant associations between CHB infection and five DPB1 alleles (two susceptibility alleles, DPB1(*) 05:01 and (*) 09:01, and three protective alleles, DPB1(*) 02:01, (*) 04:01, and (*) 04:02) were confirmed in a population comprising of 2582 Japanese individuals. Furthermore, odds ratios for CHB were higher for those with both DPB1 susceptibility alleles than for those with only one susceptibility allele; therefore, effects of susceptibility alleles were additive for risk of CHB infection. Similarly, protective alleles showed an additive effect on protection from CHB infection. Moreover, heterozygotes of any protective allele showed stronger association with CHB than did homozygotes, suggesting that heterozygotes may bind a greater variety of hepatitis B-derived peptides, and thus present these peptides more efficiently to T-cell receptors than homozygotes. Notably, compound heterozygote of the protective allele (any one of DPB1*02:01, *04:01, and *04:02) and the susceptible allele DPB1*05:01 was significantly associated with protection against CHB infection, which indicates that one protective HLA-DPB1 molecule can provide dominant protection. Identification of the HLA-DPB1 genotypes associated with susceptibility to and protection from CHB infection is essential for future analysis of the mechanisms responsible for immune recognition of hepatitis B virus antigens by HLA-DPB1 molecules.

HLA-DPB1 and HLA Class I Confer Risk of and Protection from Narcolepsy

Type 1 narcolepsy, a disorder caused by a lack of hypocretin (orexin), is so strongly associated with human leukocyte antigen (HLA) classII HLA-DQA1(∗)01:02-DQB1(∗)06:02 (DQ0602) that very few non-DQ0602 cases have been reported. A known triggering factor for narcolepsy is pandemic 2009 influenza H1N1, suggesting autoimmunity triggered by upper-airway infections. Additional effects of other HLA-DQ alleles have been reported consistently across multiple ethnic groups. Using over 3,000 case and 10,000 control individuals of European and Chinese background, we examined the effects of other HLA loci. After careful matching of HLA-DR and HLA-DQ in case and control individuals, we found strong protective effects of HLA-DPA1(∗)01:03-DPB1(∗)04:02 (DP0402; odds ratio [OR] = 0.51 [0.38-0.67], p = 1.01× 10(-6)) and HLA-DPA1(∗)01:03-DPB1(∗)04:01 (DP0401; OR = 0.61 [0.47-0.80], p = 2.07× 10(-4)) and predisposing effects of HLA-DPB1(∗)05:01 in Asians (OR = 1.76 [1.34-2.31], p = 4.71× 10(-05)). Similar effects were found by conditional analysis controlling for HLA-DR and HLA-DQ with DP0402 (OR = 0.45 [0.38-0.55] p = 8.99× 10(-17)) and DP0501 (OR = 1.38 [1.18-1.61], p = 7.11× 10(-5)). HLA-class-II-independent associations with HLA-A(∗)11:01 (OR = 1.32 [1.13-1.54], p = 4.92× 10(-4)), HLA-B(∗)35:03 (OR = 1.96 [1.41-2.70], p = 5.14× 10(-5)), and HLA-B(∗)51:01 (OR = 1.49 [1.25-1.78], p = 1.09× 10(-5)) were also seen across ethnic groups in the HLA class I region. These effects might reflect modulation of autoimmunity or indirect effects of HLA class I and HLA-DP alleles on response to viral infections such as that of influenza.

Relationship between HLA-DP gene polymorphisms and the risk of hepatocellular carcinoma: a meta-analysis.

The association between the HLA-DP single nucleotide polymorphisms (SNPs) rs3077 and rs9277535 and hepatocellular carcinoma (HCC) has been reported, but results have been inconclusive and controversial. Therefore, to investigate the relationship between these HLA-DP SNPs and HCC susceptibility, a meta-analysis of studies published before January 2014 was carried out using the PubMed and Google Scholar databases. Odds ratios (ORs) and 95% confidence intervals (CI) were calculated for HLA-DP alleles, and for co-dominant, dominant, and recessive genotype models of each SNP, based on fixed- or random-effects models. A total of nine studies from six published articles were included. The association study between rs3077 and HCC susceptibility was performed in four independent comparisons that contained 1871 cases with hepatitis B virus (HBV)-related HCC and 3207 carriers with persistent HBV. Association between rs9277535 and HCC susceptibility was examined in five separate comparisons that contained 2017 cases and 3930 carriers. Our analysis indicated a significant association of rs3077 and rs9277535 with HCC susceptibility, suggesting that rs3077 might act beneficially against HCC susceptibility (A vs G: OR = 0.884, 95%CI = 0.803-0.973, P = 0.012; GA vs GG: OR = 0.842, 95%CI = 0.733-0.967, P = 0.015; AA+GA vs GG: OR = 0.848, 95%CI = 0.744-0.968, P = 0.014), and that rs9277535 might promote HCC susceptibility (AA vs GA: OR = 1.202, 95%CI = 1.011-1.428, P = 0.037). This study suggested that HLA-DP rs3077 and rs9277535 polymorphisms are associated with HCC susceptibility in the Asian population.

New Susceptibility and Resistance HLA-DP Alleles to HBV-Related Diseases Identified by a Trans-Ethnic Association Study in Asia

Previous studies have revealed the association between SNPs located on human leukocyte antigen (HLA) class II genes, including HLA-DP and HLA-DQ, and chronic hepatitis B virus (HBV) infection, mainly in Asian populations. HLA-DP alleles or haplotypes associated with chronic HBV infection or disease progression have not been fully identified in Asian populations. We performed trans-ethnic association analyses of HLA-DPA1, HLA-DPB1 alleles and haplotypes with hepatitis B virus infection and disease progression among Asian populations comprising Japanese, Korean, Hong Kong, and Thai subjects. To assess the association between HLA-DP and chronic HBV infection and disease progression, we conducted high-resolution (4-digit) HLA-DPA1 and HLA-DPB1 genotyping in a total of 3,167 samples, including HBV patients, HBV-resolved individuals and healthy controls. Trans-ethnic association analyses among Asian populations identified a new risk allele HLA-DPB1*09∶01 (P = 1.36×10−6; OR = 1.97; 95% CI, 1.50–2.59) and a new protective allele DPB1*02∶01 (P = 5.22×10−6; OR = 0.68; 95% CI, 0.58–0.81) to chronic HBV infection, in addition to the previously reported alleles. Moreover, DPB1*02∶01 was also associated with a decreased risk of disease progression in chronic HBV patients among Asian populations (P = 1.55×10−7; OR = 0.50; 95% CI, 0.39–0.65). Trans-ethnic association analyses identified Asian-specific associations of HLA-DP alleles and haplotypes with HBV infection or disease progression. The present findings will serve as a base for future functional studies of HLA-DP molecules in order to understand the pathogenesis of HBV infection and the development of hepatocellular carcinoma.

SAT0010 Common epitope structure of HLA-DPB1 in systemic sclerosis

BackgroundSpecific alleles of HLA-DPB1 (HLA-DPB1*0901, *1301, *0301) were found to be most strongly associated with anti-topoisomerase I (Topo-I)-positive systemic sclerosis (SSc) in multiethnic genome-wide association study and HLA-analysis (1, 2)....

Predicting Non-Specifically Bound Ions: Application to Bion Webserver and Beryllium Disease

Ions are important component of all living organisms. They affect the biological macromolecules either via direct binding or as a screening ion cloud. While some ion binding is highly specific and frequently associated with the function of the macromolecule, other ions bind to the protein surface non-specifically presumably because of electrostatic attraction being strong enough to immobilize them. Recently we developed a methodology utilizing DelPhi generated potential map to predict non-specifically bound ions and this methodology is now implemented into a webserver, the BION server. We use the BION to investigate the molecular mechanism associated with the beryllium disease via malfunctioning of HLA protein. The HLA-DP allele is known to cause chronic beryllium disease in humans while binding beryllium ion. Although several binding sites for beryllium ion to HLA-DP allele are already proposed, based on genetic susceptibility of organism and chemical properties of possible ion binding sites, they are still under intensive discussion. But as far as beryllium ion is expected to bind to the surface of protein, one may expect that this bonding is non-specific, and electrostatic force favors it. The HLA-DP with predicted bound ions is then investigated to reveal the effect of the ions on the protein flexibility to infer plausible mechanism of the disease. The work is supported by NIH, NIGMS, grant number 1R01GM093937.

129-P

Aim Considering the incidence of solid organ transplant recipients who are sensitized with DP antibodies, improved methods of DP typing and of antigen equivalent grouping would be useful. A lack of serological information about most DP molecular genotypes impedes ready assignment into “serological equivalents” as practiced with other HLA loci. Since DP antibodies are most commonly identified by Single Antigen Bead (SAB) tests, the current state of the art requires comparing complicated DP genotyping data with SAB results from only a limited set of beads. We therefore sought a new, rapid method of molecular DP typing with practical “serological equivalent” assignments. Methods Linkage Biosciences’ real-time PCR technology combining allele specific amplification with melt curve detection (LinkSēq™) was used in blinded testing against a set of previously typed samples with a broad range of DP specificities. Since DP antibody response is most often directed toward a limited number of immunodominant hypervariable region epitopes, we focused on the six critical epitope regions of exon 2 of the beta locus as well as the four major groups of the alpha locus to assign DP Epitypes. Results LinkSēq reduced test time by 50% and hands-on time by up to 90% compared to SSP or SSO methods, and all LinkSēq types were concordant with the expected types. 149 HLA-DP alleles (IMGT v3.5.0) were readily grouped into 103 Epitypes based on the pattern of epitopes in each DP allele. SureTyper™ software then used donor and recipient DP genotyping information, combined with recipient SAB results, to enable an automated virtual crossmatching tool. Conclusions LinkSēq offers a rapid method of DP genotyping with a simple workflow and avoidance of post-amplification contamination. SureTyper software provides a practical approach to Epityping DP alleles, determining Epitype compatibility, and allowing virtual crossmatching without tedious manual identification of cognate antibody-epitope pairings. Antovich: Linkage Biosciences: Employee; Stockholder. Russnak: Linkage Biosciences: Employee; Stockholder. King: Linkage Biosciences: Employee; Stockholder. Ly: Linkage Biosciences: Employee; Stockholder. Quinto: Linkage Biosciences: Employee. Grumet: Linkage Biosciences: Consultant; Stockholder.

Genome-Wide Association Study Identifies HLA-DP as a Susceptibility Gene for Pediatric Asthma in Asian Populations

Asthma is a complex phenotype influenced by genetic and environmental factors. We conducted a genome-wide association study (GWAS) with 938 Japanese pediatric asthma patients and 2,376 controls. Single-nucleotide polymorphisms (SNPs) showing strong associations (P<1×10−8) in GWAS were further genotyped in an independent Japanese samples (818 cases and 1,032 controls) and in Korean samples (835 cases and 421 controls). SNP rs987870, located between HLA-DPA1 and HLA-DPB1, was consistently associated with pediatric asthma in 3 independent populations (P combined = 2.3×10−10, odds ratio [OR] = 1.40). HLA-DP allele analysis showed that DPA1*0201 and DPB1*0901, which were in strong linkage disequilibrium, were strongly associated with pediatric asthma (DPA1*0201: P = 5.5×10−10, OR = 1.52, and DPB1*0901: P = 2.0×10−7, OR = 1.49). Our findings show that genetic variants in the HLA-DP locus are associated with the risk of pediatric asthma in Asian populations.

Peptide binding prediction for the human class II MHC allele HLA-DP2: a molecular docking approach

BackgroundMHC class II proteins bind oligopeptide fragments derived from proteolysis of pathogen antigens, presenting them at the cell surface for recognition by CD4+ T cells. Human MHC class II alleles are grouped into three loci: HLA-DP, HLA-DQ and HLA-DR. In contrast to HLA-DR and HLA-DQ, HLA-DP proteins have not been studied extensively, as they have been viewed as less important in immune responses than DRs and DQs. However, it is now known that HLA-DP alleles are associated with many autoimmune diseases. Quite recently, the X-ray structure of the HLA-DP2 molecule (DPA*0103, DPB1*0201) in complex with a self-peptide derived from the HLA-DR α-chain has been determined. In the present study, we applied a validated molecular docking protocol to a library of 247 modelled peptide-DP2 complexes, seeking to assess the contribution made by each of the 20 naturally occurred amino acids at each of the nine binding core peptide positions and the four flanking residues (two on both sides).ResultsThe free binding energies (FBEs) derived from the docking experiments were normalized on a position-dependent (npp) and on an overall basis (nap), and two docking score-based quantitative matrices (DS-QMs) were derived: QMnpp and QMnap. They reveal the amino acid preferences at each of the 13 positions considered in the study. Apart from the leading role of anchor positions p1 and p6, the binding to HLA-DP2 depends on the preferences at p2. No effect of the flanking residues was found on the peptide binding predictions to DP2, although all four of them show strong preferences for particular amino acids. The predictive ability of the DS-QMs was tested using a set of 457 known binders to HLA-DP2, originating from 24 proteins. The sensitivities of the predictions at five different thresholds (5%, 10%, 15%, 20% and 25%) were calculated and compared to the predictions made by the NetMHCII and IEDB servers. Analysis of the DS-QMs indicated an improvement in performance. Additionally, DS-QMs identified the binding cores of several known DP2 binders.ConclusionsThe molecular docking protocol, as applied to a combinatorial library of peptides, models the peptide-HLA-DP2 protein interaction effectively, generating reliable predictions in a quantitative assessment. The method is structure-based and does not require extensive experimental sequence-based data. Thus, it is universal and can be applied to model any peptide - protein interaction.

Peptide binding predictions for HLA DR, DP and DQ molecules.

BackgroundMHC class II binding predictions are widely used to identify epitope candidates in infectious agents, allergens, cancer and autoantigens. The vast majority of prediction algorithms for human MHC class II to date have targeted HLA molecules encoded in the DR locus. This reflects a significant gap in knowledge as HLA DP and DQ molecules are presumably equally important, and have only been studied less because they are more difficult to handle experimentally.ResultsIn this study, we aimed to narrow this gap by providing a large scale dataset of over 17,000 HLA-peptide binding affinities for a set of 11 HLA DP and DQ alleles. We also expanded our dataset for HLA DR alleles resulting in a total of 40,000 MHC class II binding affinities covering 26 allelic variants. Utilizing this dataset, we generated prediction tools utilizing several machine learning algorithms and evaluated their performance.ConclusionWe found that 1) prediction methodologies developed for HLA DR molecules perform equally well for DP or DQ molecules. 2) Prediction performances were significantly increased compared to previous reports due to the larger amounts of training data available. 3) The presence of homologous peptides between training and testing datasets should be avoided to give real-world estimates of prediction performance metrics, but the relative ranking of different predictors is largely unaffected by the presence of homologous peptides, and predictors intended for end-user applications should include all training data for maximum performance. 4) The recently developed NN-align prediction method significantly outperformed all other algorithms, including a naïve consensus based on all prediction methods. A new consensus method dropping the comparably weak ARB prediction method could outperform the NN-align method, but further research into how to best combine MHC class II binding predictions is required.

Linking Genetic Susceptibility and T Cell Activation in Beryllium-induced Disease

Chronic beryllium disease (CBD) is a granulomatous lung disorder caused by beryllium (Be) exposure in the workplace. It is characterized by the accumulation of Be-specific CD4(+) T cells in the lung as well as persistent lung inflammation, culminating in the development of lung fibrosis. CBD occurs in 2 to 16% of Be-exposed workers depending on the individuals' genetic susceptibility and the characteristics of the exposure. Genetic susceptibility to Be-induced disease has been linked to major histocompatibility complex class II molecules. In particular, HLA-DP alleles possessing a glutamic acid at the 69th position of the beta-chain (betaGlu69) are most strongly linked to disease susceptibility. The HLA-DP alleles that present Be to T cells match those implicated in the genetic susceptibility, suggesting that the HLA contribution to disease is based on the ability of those molecules to bind and present Be to T cells. However, the structural features of betaGlu69-containing HLA-DP molecules that explain the disease association remain unknown. We have recently crystallized HLA-DP2, which is the most prevalent of the betaGlu69-containing HLA-DP molecules. Its unique structure, which includes surface exposure of betaGlu69, provides an explanation of the genetic linkage between betaGlu69-containing HLA-DP alleles and Be-induced disease.

Crystal structure of HLA-DP2 and implications for chronic beryllium disease

Chronic beryllium disease (CBD) is a fibrotic lung disorder caused by beryllium (Be) exposure and is characterized by granulomatous inflammation and the accumulation of Be-responsive CD4(+) T cells in the lung. Genetic susceptibility to CBD has been associated with certain alleles of the MHCII molecule HLA-DP, especially HLA-DPB1*0201 and other alleles that contain a glutamic acid residue at position 69 of the beta-chain (betaGlu69). The HLA-DP alleles that can present Be to T cells match those implicated in the genetic susceptibility, suggesting that the HLA contribution to disease is based on the ability of those molecules to bind and present Be to T cells. The structure of HLA-DP2 and its interaction with Be are unknown. Here, we present the HLA-DP2 structure with its antigen-binding groove occupied by a self-peptide derived from the HLA-DR alpha-chain. The most striking feature of the structure is an unusual solvent exposed acidic pocket formed between the peptide backbone and the HLA-DP2 beta-chain alpha-helix and containing three glutamic acids from the beta-chain, including betaGlu69. In the crystal packing, this pocket has been filled with the guanidinium group of an arginine from a neighboring molecule. This positively charged moiety forms an extensive H-bond/salt bridge network with the three glutamic acids, offering a plausible model for how Be-containing complexes might occupy this site. This idea is strengthened by the demonstration that mutation of any of the three glutamic acids in this pocket results in loss of the ability of DP2 to present Be to T cells.

Five HLA-DP molecules frequently expressed in the worldwide human population share a common HLA supertypic binding specificity.

Compared with DR and DQ, knowledge of the binding repertoires and specificities of HLA-DP alleles is somewhat limited. However, a growing body of literature has indicated the importance of DP-restricted responses in the context of cancer, allergy, and infectious disease. In the current study, we developed high-throughput binding assays for the five most common HLA-DPB1 alleles in the general worldwide population. Using these assays on a comprehensive panel of single-substitution analogs and large peptide libraries, we derived novel detailed binding motifs for DPB1*0101 and DPB1*0501. We also derived more detailed quantitative motifs for DPB1*0201, DPB1*0401, and DPB1*0402, which were previously characterized on the basis of sets of eluted ligands and/or limited sets of substituted peptides. Unexpectedly, all five DP molecules, originally selected only on the basis of their frequency in human populations, were found to share largely overlapping peptide motifs. Testing panels of known DP epitopes and a panel of peptides spanning a set of Phleum pratense Ags revealed that these molecules also share largely overlapping peptide-binding repertoires. This demonstrates that a previously hypothesized DP supertype extends far beyond what was originally envisioned and includes at least three additional very common DP specificities. Taken together, these DP supertype molecules are found in >90% of the human population. Thus, these findings have important implications for epitope-identification studies and monitoring of human class II-restricted immune responses.

Preformed donor-directed anti-HLA-DP antibodies may be an impediment to successful kidney transplantation

Recent reports have suggested an association of antiDP antibodies with allograft rejection and graft loss, in both primary kidney transplant recipients and in re-grafts [1–3]. However, in most cases, it is difficult to separate the effects of anti-HLA-DP antibodies from other anti-HLA class I and class II antibodies. Among non-conserved haplotypes, HLA-DP allele mismatches occur despite matching for HLA class I and class II loci, because of the lack of linkage disequilibrium between DP and other HLA loci [4]

Fully human antibody exhibits pan‐human leukocyte antigen‐DR recognition and high in vitro/vivo efficacy against human leukocyte antigen‐DR‐positive lymphomas

HD8, a fully human monoclonal antibody specific for human leukocyte antigen-DR (HLA-DR), was generated by using the transchromosome mouse that bears the human immunoglobulin genes. HD8 could bind to all 13 tested HLA-DR-positive cell lines and 35 B-cells from healthy donors. Epitope mapping revealed that while the antibody recognizes the most polymorphic region of the HLA-DRB chain, its critical epitope residues are conserved in the major alleles. Indeed, HD8 could recognize 99.2% of HLA-DRB alleles. Since its essential epitope residues are also largely conserved in HLA-DP and HLA-DQ, HD8 could recognize 100% and 66% of the HLA-DP and HLA-DQ alleles tested, respectively. HD8 exerted strong antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity in vitro, and significantly extended the life span of immunocompromised mice inoculated with non-Hodgkin lymphoma cell lines. The HD8 antibody may be highly useful in HLA-DR-targeted immunotherapy as it is likely to evoke similarly strong responses in individuals carrying different HLA-DR alleles.