Human Leukocyte Antigen Polymorphisms Research Articles

Human leucocyte antigen association of patients with Stevens-Johnson syndrome/toxic epidermal necrolysis with severe ocular complications in Han Chinese

Background/aimsStevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) induced by cold medicine (CM) may result in severe ocular complications (SOCs). The purpose of this study was to investigate the human leucocyte antigen (HLA)...

Off-the-Shelf, Immune-Compatible Human Embryonic Stem Cells Generated Via CRISPR-Mediated Genome Editing

Human embryonic stem cells (hESCs) hold promise in regenerative medicine but allogeneic immune rejections caused by highly polymorphic human leukocyte antigens (HLAs) remain a barrier to their clinical applications. Here, we used a CRISPR/Cas9-mediated HLA-editing strategy to generate a variety of HLA homozygous-like hESC lines from pre-established hESC lines. We edited four pre-established HLA-heterozygous hESC lines and created a mini library of 14 HLA-edited hESC lines in which single HLA-A and HLA-B alleles and both HLA-DR alleles are disrupted. The HLA-edited hESC derivatives elicited both low T cell- and low NK cell-mediated immune responses. Our library would cover about 40% of the Asian-Pacific population. We estimate that HLA-editing of only 19 pre-established hESC lines would give rise to 46 different hESC lines to cover 90% of the Asian-Pacific population. This study offers an opportunity to generate an off-the-shelf HLA-compatible hESC bank, available for immune-compatible cell transplantation, without embryo destruction.Graphical

The combinatorial diversity of KIR and HLA class I allotypes in Peninsular Malaysia.

Killer cell immunoglobulin-like receptors (KIRs) interact with polymorphic human leucocyte antigen (HLA) class I molecules, modulating natural killer (NK) cell functions and affecting both the susceptibility and outcome of immune-mediated diseases. The KIR locus is highly diverse in gene content, copy number and allelic polymorphism within individuals and across geographical populations. To analyse currently under-represented Asian and Pacific populations, we investigated the combinatorial diversity of KIR and HLA class I in 92 unrelated Malay and 75 Malaysian Chinese individuals from the Malay Peninsula. We identified substantial allelic and structural diversity of the KIR locus in both populations and characterized novel variations at each analysis level. The Malay population is more diverse than Malay Chinese, likely representing a unique history including admixture with immigrating populations spanning several thousand years. Characterizing the Malay population are KIR haplotypes with large structural variants present in 10% individuals, and KIR and HLA alleles previously identified in Austronesian populations. Despite the differences in ancestries, the proportion of HLA allotypes that serve as KIR ligands is similar in each population. The exception is a significantly reduced frequency of interactions of KIR2DL1 with C2+ HLA-C in the Malaysian Chinese group, caused by the low frequency of C2+ HLA. One likely implication is a greater protection from preeclampsia, a pregnancy disorder associated with KIR2DL1, which shows higher incidence in the Malay than in the Malaysian Chinese. This first complete, high-resolution, characterization of combinatorial diversity of KIR and HLA in Malaysians will form a valuable reference for future clinical and population studies.

RBM-MHC: A Semi-Supervised Machine-Learning Method for Sample-Specific Prediction of Antigen Presentation by HLA-I Alleles.

SummaryThe recent increase of immunopeptidomics data, obtained by mass spectrometry or binding assays, opens up possibilities for investigating endogenous antigen presentation by the highly polymorphic human leukocyte antigen class I (HLA-I) protein. State-of-the-art methods predict with high accuracy presentation by HLA alleles that are well represented in databases at the time of release but have a poorer performance for rarer and less characterized alleles. Here, we introduce a method based on Restricted Boltzmann Machines (RBMs) for prediction of antigens presented on the Major Histocompatibility Complex (MHC) encoded by HLA genes—RBM-MHC. RBM-MHC can be trained on custom and newly available samples with no or a small amount of HLA annotations. RBM-MHC ensures improved predictions for rare alleles and matches state-of-the-art performance for well-characterized alleles while being less data demanding. RBM-MHC is shown to be a flexible and easily interpretable method that can be used as a predictor of cancer neoantigens and viral epitopes, as a tool for feature discovery, and to reconstruct peptide motifs presented on specific HLA molecules.

The amino acid variants in HLA II molecules explain the major association with adult-onset Still's disease in the Han Chinese population

Adult-onset Still's disease (AOSD) is a rare autoinflammatory disease with systemic involvement, and its pathophysiology remains unclear. Genome-wide association studies (GWAS) in the Chinese population have revealed an association between AOSD and the major histocompatibility complex (MHC) locus; however, causal variants in the MHC remain undetermined. In the present study, we identified independent amino-acid polymorphisms in human leukocyte antigen (HLA) molecules that are associated with Han Chinese patients with AOSD by fine-mapping the MHC locus. Through conditional analyses, we identified position 34 in HLA-DQα1 (p = 1.44 × 10−14) and Asn in HLA-DRβ1 position 37 (p = 5.12 × 10−11) as the major determinants for AOSD. Moreover, we identified the associations for three main HLA class II alleles: HLA-DQB1*06:02 (OR = 2.70, p = 3.02 × 10−14), HLA-DRB1*15:01 (OR = 2.44, p = 3.66 × 10−13), and HLA-DQA1*01:02 (OR = 1.97, p = 1.09 × 10−9). This study reveals the relationship between functional variations in the class II HLA region and AOSD, implicating the MHC locus in the pathogenesis of AOSD.

HLA Polymorphisms Are Associated with Treatment-Free Remission Following Discontinuation of Tyrosine Kinase Inhibitors in Chronic Myeloid Leukemia.

Treatment-free remission (TFR) is one of the therapeutic goals for patients with chronic phase chronic myeloid leukemia (CML-CP). Although previous reports indicated that antitumor immunity contributes to TFR, its determinants are still unclear. We previously reported that allelic polymorphisms of killer immunoglobulin-like receptors (KIR) and human leukocyte antigens (HLA) are associated with achievement of deep molecular response (DMR) in patients with CML-CP. Here, we examined the association between TFR and polymorphisms of KIRs and HLAs in patients who discontinued tyrosine kinase inhibitors (TKI). Seventy-six patients were enrolled, and their KIR and HLA polymorphisms and natural killer (NK) cell activation status were investigated as previously described. Overall, 33 patients discontinued TKIs, and 21 of 33 achieved TFR [63.6%; 95% confidence interval (CI), 44.9%-77.5%] at 1 year. Multivariate analysis revealed that male sex (HR, 0.157; 95% CI, 0.031-0.804; P = 0.003) and HLA-A*02:01, *11:01, or *24:02 (HR, 6.386; 95% CI, 1.701-23.980; P = 0.006) were associated with TFR. Patients who achieved DMR and discontinued TKIs exhibited higher NK cell activation status than those who did not. By contrast, there were no significant differences in NK cell activation status between the patients who achieved TFR and those who experienced molecular relapse. These results suggest NK cell activation status contributes to achievement of DMR, whereas T-cell-mediated immunity contributes to TFR in patients with CML-CP.

Off-the-Shelf, Immune-Compatible Human Embryonic Stem Cells Generated Via CRISPR-Mediated Genome Editing

Human embryonic stem cells (hESCs) hold promise in regenerative medicine but allogeneic immune rejections caused by highly polymorphic human leukocyte antigens (HLAs) remain a barrier to their clinical applications. Here, we used a CRISPR/Cas9-mediated HLA-editing strategy to generate a variety of HLA homozygous-like hESC lines from pre-established hESC lines. We edited four pre-established HLA-heterozygous hESC lines and created a mini library of 14 HLA-edited hESC lines in which single HLA-A and HLA-B alleles and both HLA-DR alleles are disrupted. The HLA-edited hESC derivatives elicited both low T cell- and low NK cell-mediated immune responses. Our library would cover about 40% of the Asian-Pacific population. We estimate that HLA-editing of only 19 pre-established hESC lines would give rise to 46 different hESC lines to cover 90% of the Asian-Pacific population. This study offers an opportunity to generate an off-the-shelf HLA-compatible hESC bank, available for immune-compatible cell transplantation, without embryo destruction.

Revisiting the association between human leukocyte antigen and end-stage renal disease.

Multiple works have studied possible associations between human leukocyte antigen (HLA) alleles and end stage renal disease (ESRD) showing, however, contradictory and inconsistent results. Here, we revisit the association between ESRD and HLA antigens, comparing HLA polymorphism (at HLA-A, -B, -C, -DRB1, -DQB1 and DQA1 loci) in ESRD patients (n = 497) and controls (n = 672). Our data identified several HLA alleles that displayed a significant positive or negative association with ESRD. We also determined whether heterozygosity or homozygosity of the ESRD-associated HLA alleles at different loci could modify the prevalence of the disease. Few HLA allele combinations displayed significant associations with ESRD, among which A*3_26 combination showed the highest strength of association (OR = 4.488, P≤ 0.05) with ESRD. Interestingly, the age of ESRD onset was not affected by HLA allele combinations at different loci. We also performed an extensive literature analysis to determine whether the association of HLA to ESRD can be similar across different ethnic groups. Our analysis showed that at least certain HLA alleles, HLA-A*11, HLA-DRB1*11, and HLA-DRB1*4, display a significant association with ESRD in different ethnic groups. The findings of our study will help in determining possible protective or susceptible roles of various HLA alleles in ESRD.

HLA genetic polymorphisms and prognosis of patients with COVID-19

ObjectiveDifferent genetic polymorphisms of human leukocyte antigen (HLA) have been associated with the risk and prognosis of autoimmune and infectious diseases. The objectives of this study were to determine whether there is an association between HLA genetic polymorphisms and the susceptibility to and mortality of coronavirus disease 2019 (COVID-19) patients.DesignObservational and prospective study.SettingEight Intensive Care Units (ICU) from 6 hospitals of Canary Islands (Spain).PatientsCOVID-19 patients admitted in ICU and healthy subjects.InterventionsDetermination of HLA genetic polymorphisms.Main variable of interestMortality at 30 days.ResultsA total of 3886 healthy controls and 72 COVID-19 patients (10 non-survivors and 62 survivor patients at 30 days) were included. We found a trend to a higher rate of the alleles HLA-A*32 (p = 0.004) in healthy controls than in COVID-19 patients, and of the alleles HLA-B*39 (p = 0.02) and HLA-C*16 (p = 0.02) in COVID-19 patients than in healthy controls; however, all these p-values were not significant after correction for multiple comparisons. Logistic regression analysis showed that the presence of certain alleles was associated with higher mortality, such as the allele HLA-A*11 after controlling for SOFA (OR = 7.693; 95% CI = 1.063–55.650; p = 0.04) or APACHE-II (OR = 11.858; 95% CI = 1.524–92.273; p = 0.02), the allele HLA-C*01 after controlling for SOFA (OR = 11.182; 95% CI = 1.053–118.700; p = 0.04) or APACHE-II (OR = 17.604; 95% CI = 1.629–190.211; p = 0.02), and the allele HLA-DQB1*04 after controlling for SOFA (OR = 9.963; 95% CI = 1.235–80.358; p = 0.03).ConclusionsThe new finding from our preliminary study of small sample size was that HLA genetic polymorphisms could be associated with COVID-19 mortality; however, studies with a larger sample size before definitive conclusions can be drawn.

CAN EPITOPE MATCHING OUTMATCH TRADITIONAL HLA MATCHING?

Collaborative Transplant Study. Introduction: Pre-transplant presence and post-transplant development of alloantibodies against highly polymorphic human leukocyte antigen (HLA) allele mismatches (mm) play a major role in rejection of kidney allografts. However, antibodies recognize small sequences on HLA alleles called epitopes and the same epitope can be present on different alleles, impairing the precision of matching. Using the Collaborative Transplant Study database, we analyzed whether a T-cell epitope-based matching of donor-recipient pairs using the PIRCHE-II algorithm is a better predictor of graft survival than the currently applied allele group-based HLA-A, -B, -DR matching. Methods: 68,606 European deceased donor kidney-only transplantations during 1996–2016 were analyzed. PIRCHE-II mismatch score was calculated based on split typing using the 2007 NMDP haplotype frequency database and the PIRCHE matching service. Multivariable Cox regression analyses were performed to calculate hazard ratios (HRs) for death-censored graft loss. Correlation was analyzed with Spearman’s rank correlation. In order to achieve comparable HRs, a log-transformed PIRCHE-II score was used, followed by a linear transformation to match the value range of 0–6 HLA A+B+DR mm. Linear transformations in Cox regression analysis change the HR per point without changing the P- and Z-values. Results and Discussion: The HLA mismatch-derived PIRCHE-II score correlated strongly with the number of HLA mm (correlation coefficient ρ=0.65, P<0.001). Cox regression analyses revealed that Pirche II score and HLA mm are predictive confounders for death-censored graft loss at year 5 with highly significant prognostic power (Z-value for Pirche II: 9.8; for HLA: 11.2; P<0.001) (Table 1).The full Cox model per transformed PIRCHE-II score without HLA mm resulted in a hazard ratio (HR) for graft loss of 1.102 (95% CI=1.081–1.123; P<0.001). When HLA mm were added to the model, the HR per PIRCHE-II score decreased to 1.042 but remained statistically significant (95% CI=1.015–1.071; P=0.002) (Table 1). Overall, considering the HLA loci currently used for typing at split antigen level, HLA mm still had a higher predictive value than the PIRCHE-II score (11.2 vs. 9.8) regarding graft survival. As illustrated in Figure 1, the variance in PIRCHE-II score increased with higher number of HLA mm.Therefore, the possible clinical benefit of PIRCHE-II score matching improved with higher number of HLA mismatches. As demonstrated in Table 1, the risk of graft loss increases with each additional PIRCHE-II score. Conclusion: Our results indicate that PIRCHE-II score is useful and can be included into matching algorithms. However, it cannot fully replace traditional HLA matching. There seems to be information on immunological differences PIRCHE-II score cannot cover in its present form using HLA typing data at split level. This needs to be analyzed also for HLA matching at 4-digit molecular typing level.

Association between human leukocyte antigen gene polymorphisms and multiple EPIYA-C repeats in gastrointestinal disorders

BACKGROUNDPolymorphisms of human leukocyte antigen (HLA) genes are suggested to increase the risk of gastric cancer (GC).AIMTo investigate the HLA allele frequencies of patients with GC relative to a control group in terms of CagA+ multiple (≥ 2) EPIYA-C repeats.METHODSThe patient group comprised 94 patients [44 GC and 50 duodenal ulcer (DU) patients], and the control group comprised 86 individuals [(50 non-ulcer dyspepsia patients and 36 people with asymptomatic Helicobacter pylori (H. pylori)]. Polymerase chain reaction was performed for the amplification of the H. pylori cagA gene and typing of EPIYA motifs. HLA sequence-specific oligonucleotide (SSO) typing was performed using Lifecodes SSO typing kits (HLA-A, HLA-B HLA-C, HLA-DRB1, and HLA-DQA1-B1 kits).RESULTSThe comparison of GC cases in terms of CagA+ multiple (≥ 2) EPIYA-C repeats showed that only the HLA-DQB1*06 allele [odds ratio (OR): 0.37, P = 0.036] was significantly lower, but significance was lost after correction (Pc = 0.1845). The HLA-DQA1*01 allele had a high ratio in GC cases with multiple EPIYA-C repeats, but this was not significant in the univariate analysis. We compared allele frequencies in the DU cases alone and in GC and DU cases together using the same criterion, and none of the HLA alleles were significantly associated with GC or DU. Also, none of the alleles were detected as independent risk factors after the multivariate analysis. On the other hand, in a multivariate logistic regression with no discriminative criterion, HLA-DQA1*01 (OR = 1.848), HLA-DQB1*06 (OR = 1.821) and HLA-A*02 (OR = 1.579) alleles were detected as independent risk factors for GC and DU.CONCLUSIONNone of the HLA alleles were detected as independent risk factors in terms of CagA+ multiple EPIYA-C repeats. However, HLA-DQA1*01, HLA-DQB1*0601, and HLA-A*2 were independent risk factors with no criterion in the multivariate analysis. We suggest that the association of these alleles with gastric malignancies is not specifically related to cagA and multiple EPIYA C repeats.

Polymorphism of HLA-A, -B, -C, -DRB1 and -DQB1 Allele and Haplotype Frequency at High Resolution in Guangxi Zhuang Population

To analyze the characteristics of allelic and haplotypic polymorphisms of human leukocyte antigens at HLA-A, -B, -C, DRB1 and DQB1 loci in Guangxi Zhuang population. Polymerase chain reaction-sequence based typing (PCR-SBT) was used to detect. The five loci (HLA-A, -B, -C, -DRB1, -DQB1) in 350 unrelated Zhuang ethnic individual from Guangxi region. Allelic and haplotypic frequencies were calculated by using Arlequin software 3.5.2.2. Phylogeny tree were constructed by using MEGA software 6.0, and SPSS software was used for principal component analysis. Among the five loci in the population, only HLA-A and DRB1 loci were observed as departures from Hardy-Weinberg expectations. A total of 19 HLA-A, 42 HLA-B, 22 HLA-C, 25 HLA-DRB1 and 15 HLA-DQB1 alleles were found in 350 samples. The most highest frequent alleles were A*11: 01(28.57%), B*46: 01(14.00%), C*01: 02(18.43%), DRB1*16: 02 (15.71%）and DQB1*05: 02 (35.00%) . The most common five loci haplotype was A*33: 03-C*03: 02-B*58: 01-DRB1*03: 01-DQB1*02: 01（6.86%）. The phylogenetic tree analysis showed that Guangxi Zhuang population had a relative close genetic relationship with southern Han Chinese populations. This reaserch found that the HLA-A, B, C, DRB1 and DQB1 loci are highly polymorphic in Guangxi Zhuang population.

A CD33 frameshift variant is associated with neuromyelitis optica spectrum disorders

BackgroundNeuromyelitis optica spectrum disorder (NMOSD) is a rare neuroimmunology disorder predominantly affecting the East Asia population, the reason for this preference remains unknown. Genetic factors such as polymorphisms in human leukocyte antigen (HLA) and interleukins (IL) genes have been reported. Although the familial occurrence of NMOSD is rare, it supports that genetic factors may play a role. MethodsWhole exome sequencing (WES) study was performed on the affected mother and daughter, as well as the unaffected father in a Taiwanese family with NMOSD. A cohort of 19 sporadic patients with aquaporin 4 antibody (AQP4-Ab) positive NMOSD was also recruited; all fulfilled the 2015 International NMOSD Diagnosis Criteria. Sanger sequencing was performed on exon 4 of the CD33 gene on the sporadic NMOSD cohort. ResultsWES study revealed a 19 base pair deletion in exon 4 of the CD33 gene, resulting in frameshift premature truncating protein, which segregated with the affected status. CD33 was the most likely candidate gene due to its known function in immune regulation. A total of 19 sporadic NMOSD patients were tested using Sanger sequencing, including 3 patients with other concomitant autoimmune disorders. Two additional NMOSD patients were found to have the same CD33 frameshift variant, which accounts for 19.04% of all NMOSD patients, and 15% following correction for the familial cases; compared to 2% in Taiwanese population controls. ConclusionIn this study, we identified a 19 base pair deletion in the CD33 gene may be a potential risk locus for NMOSD, which is predicted to cause loss of function of CD33. The loss of CD33 inhibitory function may affect the regulation of the immune system in NMOSD patients. This finding requires further larger cohorts of NMOSD patients and functional study to corroborate.

Gene Polymorphisms and Their Association to Coronavirus Family Infections: Susceptibility in Different Populations

Human leukocyte antigen (HLA) loci are highly polymorphic and determine differential features of the immune response in subjects from different regions. HLA genes have been proposed to determine genetic susceptibility to several diseases, particularly to viral infections. Moreover, it has been suggested that each ethnic group could have a different specificity of T-lymphocyte reactivity to the same viral infections. In this review, we analyzed the distribution of HLA types in countries of the Asian, European and North African region. Also, we studied the relation between these HLA polymorphisms and susceptibility to infection by the coronavirus. Our findings indicated that homozygosity would increase susceptibility to viral infections and, in some cases, to coronavirus infection. HLA types showing higher susceptibility were reported in Asian population, including China, Singapore, and Taiwan. In contrast, lower susceptibility HLA variants were detected among African populations, some Asian populations, and Mediterranean populations. The presented evidence along with the spread pattern of COVID-19 infection suggests that HLA genetic variants might be related to its infection susceptibility and severity. The investigation of HLA genetic variants distribution would be a useful tool to predict different populations’ susceptibility to viral infections.

SNP-HLA Reference Consortium (SHLARC): HLA and SNP data sharing for promoting MHC-centric analyses in genomics.

Genome‐wide associations studies have repeatedly identified the major histocompatibility complex genomic region (6p21.3) as key in immune pathologies. Researchers have also aimed to extend the biological interpretation of associations by focusing directly on human leukocyte antigen (HLA) polymorphisms and their combination as haplotypes. To circumvent the effort and high costs of HLA typing, statistical solutions have been developed to infer HLA alleles from single‐nucleotide polymorphism (SNP) genotyping data. Though HLA imputation methods have been developed, no unified effort has yet been undertaken to share large and diverse imputation models, or to improve methods. By training the HIBAG software on SNP + HLA data generated by the Consortium on Asthma among African‐ancestry Populations in the Americas (CAAPA) to create reference panels, we highlighted the importance of (a) the number of individuals in reference panels, with a twofold increase in accuracy (from 10 to 100 individuals) and (b) the number of SNPs, with a 1.5‐fold increase in accuracy (from 500 to 24,504 SNPs). Results showed improved accuracy with CAAPA compared to the African American models available in HIBAG, highlighting the need for precise population‐matching. The SNP‐HLA Reference Consortium is an international endeavor to gather data, enhance HLA imputation and broaden access to highly accurate imputation models for the immunogenomics community.

Variability in the frequency of single nucleotide polymorphisms of N-acetyl transferase 2 (NAT2) gene among the different ethnic groups in Taiwan

Significant variations in the frequency of single nucleotide polymorphisms (SNPs) of human leukocyte antigen among Taiwan's aboriginal tribes and high homogeneity within each tribe have been reported. To identify variations in genetic polymorphisms of drug-metabolizing enzyme in seven of Taiwan's ethnic groups, the SNPs of N-acetyl transferase 2, a conjugation enzyme in phase II metabolism, were investigated. Methods: Three SNPs of NAT2, NAT2*5, NAT2*6, and NAT2*7, were determined by the TaqMan® method and subsequently confirmed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Our results showed statistically significant variations in the frequency of NAT2 genotype categories according to the 3 SNPs of NAT2 within 7 Taiwanese ethnic groups (Chi-square = 32.08, p<0.05). The distribution of the frequency of the slow acetylator genotype ranged from 32.0% in the Hakka population to 75.5% in the Paiwan population. A lack of NAT2*5 SNP alleles was found in the Atayal population, while a NAT2*5 allele frequency of 31.6% was observed in the Paiwan group. The frequencies of allele NAT2*6 and NAT2*7 in the investigated ethnic groups ranged from 11.2-37.0% and 17.0-53%, respectively. Our results also showed the considerable variations in drug-metabolizing enzyme NAT2 genotypes among Taiwan's aboriginal and general population. The variation in the genetic polymorphisms of drug-metabolizing enzyme in Taiwan's groups is worthy of further study to understand different therapeutic and adverse drug responses in ethnic groups.

Targeted analysis of polymorphic loci from low-coverage shotgun sequence data allows accurate genotyping of HLA genes in historical human populations

The highly polymorphic human leukocyte antigen (HLA) plays a crucial role in adaptive immunity and is associated with various complex diseases. Accurate analysis of HLA genes using ancient DNA (aDNA) data is crucial for understanding their role in human adaptation to pathogens. Here, we describe the TARGT pipeline for targeted analysis of polymorphic loci from low-coverage shotgun sequence data. The pipeline was successfully applied to medieval aDNA samples and validated using both simulated aDNA and modern empirical sequence data from the 1000 Genomes Project. Thus the TARGT pipeline enables accurate analysis of HLA polymorphisms in historical (and modern) human populations.

Identifying the HLA DRB1-DQB1 molecules and predicting epitopes associated with high-risk HPV infection clearance and redetection

Several determining factors are involved in HPV infection outcomes; human leukocyte antigen (HLA) polymorphisms have been described as related factors. This study has ascertained the effect of genetic variation on HLA-DRB1 and DQB1 genes on HPV-16/-18/-31/-33/-45 and -58 clearance and redetection in Colombian women. PCR and qPCR were used for viral identification and the Illumina MiSeq system was used for HLA-typing of cervical samples (n = 276). Survival models were adjusted for identifying alleles/haplotypes related to HPV clearance/redetection; L1/L2 protein-epitope binding to MHC-II molecules was also predicted. Significant associations suggested effects favouring or hampering clearance/redetection events depending on the viral type involved in infection, e.g. just DRB1*12:01:01G favoured HPV-16 (coeff: 4.8) and HPV-45 clearance (coeff: 12.65) whilst HPV-18 (coeff: 2E-15), HPV-31 (coeff: 8E-17) and HPV-58 hindered elimination (coeff: 1E-14). An effect was only observed for some alelles when configured as haplotypes, e.g. DRB1*04:07:01G (having the greatest frequency in the target population) was associated with DQB1*02:01:1G or *03:02:03. Epitope prediction identified 23 clearance-related peptides and 29 were redetection-related; eight might have been related to HPV-16/-18 and -58 persistence and one to HPV-18 elimination. HLA allele/haplotype relationship with the course of HPV infection (clearance/redetection) depended on the infecting HPV type, in line with the specific viral epitopes displayed.

Polymorphic Region-Specific Antibody for Evaluation of Affinity-Associated Profile of Chimeric Antigen Receptor

Antibody applications in cancer immunotherapy involve diverse strategies, some of which redirect T cell-mediated immunity via engineered antibodies. Affinity is a trait that is crucial for these strategies, as optimal affinity reduces unwanted side effects while retaining therapeutic function. Antibody-antigen pairs possessing a broad affinity range are required to define optimal affinity and to investigate the affinity-associated functional profiles of T cell-engaging strategies such as bispecific antibodies and chimeric antigen receptor-engineered T cells. Here, we demonstrate the unique binding characteristic of the developed antibody clone MVR, which exhibits robust binding to B-lymphoid cell lines. Intriguingly, MVR specifically recognizes the highly polymorphic human leukocyte antigen (HLA)-DR complex and exhibits varying affinities that are dependent upon the HLA-DRB1 allele type. Remarkably, MVR binds to the conformational epitope that consists of two hypervariable regions. As an application of MVR, we demonstrate an MVR-engineered chimeric antigen receptor (CAR) that elicits affinity-dependent function in response to a panel of target cell lines that express different HLA-DRB1 alleles. This tool evaluates the effect of affinity on cytotoxic killing, polyfunctionality, and activation-induced cell death of CAR-engineered T cells. Collectively, MVR exhibits huge potential for the evaluation of the affinity-associated profile of T cells that are redirected by engineered antibodies.

Comprehensive assessment of association between HLA polymorphisms and acute leukemia in Iranian population

Immune system has a prominent role in both prevention and treatment of leukemia. Based on the role of human leukocyte antigen (HLA) in determination of response to therapeutic options and risk of development of leukemia, several studies have addressed association between HLA alleles and this disorder. Here, we conducted a single-center analysis of HLA-A/-B/-DRB1 distribution in Iranian patients with acute leukemia. The study enrolled 92 patients with acute lymphoblastic leukemia (ALL), 76 patients with acute myeloid leukemia (AML) and 90 healthy controls. HLA-A/-B/-DRB1 alleles were identified using PCR method with sequence specific primers. There was no significant difference in distribution of HLA-A/-B/-DRB1 alleles between three study subgroups. However, distribution of HLA-A-B-DRB1 haplotypes was significantly different between AML and ALL patients and between both groups of patients and controls (P<0.0001). The results of the current study should be verified in future studies with larger sample sizes.