HLA-B27 subtypes determination in patients with ankylosing spondylitis from Zulia,Venezuela

To perform an investigation regarding the distribution of the human leukocyte antigen (HLA)-B27 subtypes in the Zulian population with ankylosing spondylitis (AS), 48 unrelated Mestizos, HLA-B27 positive by serology, were studied using the polymerase chain reaction-specific sequence oligonucleotides probe (PCR-SSOP) and specific sequence primers (SSP) to analyze the polymorphism in exons 2 and 3 of the HLA-B27 gene. Only two of eight HLA-B27 subtypes studied (B*2701-B*2708) were found. The distribution of these alleles in the population of patients was: B*2705, 68.8%, and B*2702, 31.2%. B*2705 subtype showed significant association with patients being male. In the healthy controls, the most common subtype was B*2708. These results were compared with frequencies reported in other Mestizo and Spanish populations and showed significant differences, such as a high frequency of B*2702. Such results show that HLA*B2705 and HLA*B2702 are the subtypes most frequently associated with AS in our Mestizo population and suggest a possible protector role for HLA*B2708, which was found only in the healthy population.     

Predominant association of HLA-B*2704 with ankylosing spondylitis in Chinese Han patients

Abstract
The HLA-B27 subtypes have a varied racial and ethnic prevalence throughout the world. However, the association of B27-subtypes with ankylosing spondylitis (AS) in the mainland China is unknown. To determine the association of B27-subtypes with AS in the Mainland Chinese Han population, a total of unrelated 153 patients with AS were enrolled in a large case-control association study, and 1545 unrelated, healthy, ethnically matched blood donors were included as controls. The genotyping of B27 and its subtypes was performed using the polymerase chain reaction with sequence specific primers (PCR-SSP). A total of 130 (84.97%) AS patients and 61 (3.95%) healthy controls were B27 positive. Three B27-subtypes, B*2704, B*2705 and B*2710, were further identified, of which both B*2704 and B*2705 were strongly AS associated. B*2710 was only detected in one AS patient and two other healthy controls. Considering only B27-positive cases and controls, a statistically different frequency of B27-subtypes was observed, with an over-representation of B*2704 ( P = 0.018). B*2704 was clearly more strongly associated than B*2705 with AS [odds ratio (OR ) = 2.4, P = 0.011]. Furthermore, a combined analysis including three previous studies of B27-subtype distributions in Chinese AS cases confirmed the stronger association of B*2704 with AS than B*2705 (OR = 2.5, P = 0.00094).     

HLA-B27 in the Greek Cypriot population: distribution of subtypes in patients with ankylosing spondylitis and other HLA-B27-related diseases. The possible protective role of B*2707

The major purpose of the present study was to investigate the frequency of human leukocyte antigen (HLA)-B27 alleles in healthy controls and in patients with ankylosing spondylitis (AS) and other HLA-B27–related diseases in the Greek Cypriot population. We selected 102 HLA-B27–positive individuals (60 controls and 42 patients). Typing of the HLA-B27 alleles was performed by polymerase chain reaction amplification with sequence-specific primers. Only two alleles were detected in the patient group: B*2702 (n = 31, 73.8%) and B*2705 (n = 11, 26.2%). The HLA-B*2707 allele was detected (n = 10, 16.7%) only in the healthy controls in addition to the B*2702 (n = 31, 51.7%) and B*2705 (n = 19, 31.7%) alleles. Our results show a restricted number of HLA-B27 subtypes associated with AS and other B27-related diseases and an elevated frequency of the B*2702 allele in the AS patients. The allele B*2707 seems to have a protective role in the population studied because it was found only in the healthy controls.     

HLA B-27 subtypes in Turkish patients with spondyloarthropathy and healthy controls

The frequency and the distribution of HLA-B27 subtypes in spondylarthropathy (SpA) patients and controls were investigated in a sample Turkish population. B27 subtyping was performed by PCR-SSP method in two groups: 49 unrelated HLA-B27 positive Turkish patients with the diagnosis of SpA according to the European Spondyloarthropathy Study Group Criteria, and 55 HLA-B27 positive healthy controls. The frequency of HLA-B*27 was 2.6% in the Turkish population, and B*2705 was the predominant allele among patients with SpA. The difference was mainly between male patients and male controls The proportion of B*2705 among B27-positive patients and controls was significantly different (P=0.02). Our study supports other reports from different populations which showed that B*2705 and B*2702 were more frequent in Caucasian patients with SpA.     

HLA-B*27 subtypes in Northern and Northeastern Thais, Karens, and Bamars determined by a high-resolution PCR-SSP technique

Human leukocyte antigens (HLA), class I, are a group of antigens expressed on most nucleated cell surfaces. They transport endogenous peptides to the cell surface for recognition by T-cell receptors. Their functions are involved in immune responses. Many diseases are associated with HLA alleles, especially HLA-B*27 that is strongly associated with ankylosing spondylitis (AS). HLA-B*27 consists of 42 subtypes. Different subtypes of HLA-B*27 were reported in different ethnic groups of AS patients. In this study, a high-resolution polymerase chain reaction–sequence-specific primer technique has been developed to define all the HLA-B*27 subtypes with a total of 29 primer mixtures. Two of the primer mixes were used to detect the HLA-B*27 -specific group, and 27 primer mixes were used to identify 42 subtypes ( B*2701–B*2721 and B*2723–B*27 43). The HLA-B*27 -group-specific primers have been tested in unrelated healthy subjects; 846 Northeastern Thais (NET), 334 Northern Thais (NT), 264 Karens, and 310 Bamars. Sixty-three NET (phenotype frequency, PF = 7.4%), 24 NT (PF = 7.1%), 5 Karens (PF = 1.8%), and 12 Bamars (PF = 3.9%) were positive for HLA-B*27 . Only B*2704 was found in Karens, whereas B*2704 , B*2705/37/39 , B*2706 , and B*2707 were found in NET and NT. In Bamars, B*2704 , B*2705/37/39 , B*2706 , and B*2725 were found. The distribution of HLA-B*27 subtypes was compared with other studies in Asian and Caucasian populations. Significant differences of the distribution of HLA-B*27 subtypes were found in most of the populations. This study established a simple technology for HLA-B*27 subtyping and provided basic information for anthropology and further studies in disease associations.     

Diversity of human leukocyte antigen-B27 alleles in Han population of Hunan province, southern China

This study was to investigate the frequency of HLA-B27 and its subtypes in the Han population of Hunan province, southern China. One hundred and sixty-nine healthy unrelated donors were tested for HLA-B27 by polymerase chain reaction-sequence-specific primer (PCR-SSP). One hundred and twenty-eight B27-positive spondyloarthropathy patients and 18 B27-positive healthy controls were subtyped using the high-resolution PCR-SSP. The phenotype frequency of human leukocyte antigen (HLA)-B27 was found to be 2.36% in healthy population. Five B27 alleles were identified: B*2704, B*2705, B*2706, B*2707, and B*2724. No significant difference was found in the distribution of HLA-B27 subtypes between the patients and controls studied. Notably, B*2724 was observed in a juvenile patient with ankylosing spondylitis. This subtype has not been previously reported in Chinese ankylosing spondylitis (AS) patients and other ethnic groups.     

HLA-A*9, a probable secondary susceptibility marker to ankylosing spondylitis in Basque patients

HLA-B27 is strongly associated to ankylosing spondylitis (AS). The objective of our study was to analyze HLA-B27 association, B27 subtype distribution and frequency of other HLA class I and DR antigens in a group of Basque AS patients. HLA class I antigens were typed serologically and HLA-B27 and A9 subtypes were determined by DNA typing in samples from 46 patients with AS, 54 B27-positive spondyloarthropathies, 82 healthy subjects and 20 B27-positive controls. A class I HLA 9.2 kb PvuII restriction fragment length polymorphism (RFLP), previously associated with AS, was analyzed in a representative group of patients and controls. We found that HLA-B*2705 conferred a relative risk of 126 for AS in this group. HLA-A9 (A*2402) allele was significantly increased in AS patients compared with healthy controls and B27-positive control group (Pcorr<0.0001) and also increased in patients affected with peripheral arthritis. No association between class I HLA 9.2 Kb RFLP and AS was found. These results suggest that HLA-A*9 allele itself or another linked gene could act as a secondary and independent susceptibility allele to AS.     

HLA-B27 and ankylosing spondylitis: tales from China

Abstract
The two most frequent HLA-B27 subtypes worldwide are B*2704 and B*2705. In the Han population of China B*2704 and, to a lower extent, B*2705 are found with significant frequency, and both are associated to ankylosing spondylitis (AS). Two articles in this issue report that the association to AS in this ethnic group is stronger for B*2704 than for B*2705. Thus, at least among the Han, B*2704 would be the strongest known susceptibility factor for AS.     

HLA-B27 subtypes in chinese patients with ankylosing spondylitis

The HLA-B27 allele has been extensively studied due to its strong association with ankylosing spondylitis (AS). In order to identify B27 alleles in Chinese patients with AS from the Shanghai area, we joined the AHS#5 of the 12 IHW and total of 68 B27 positive patients and 7 B27 positive normal persons have been investigated using polymerase chain reaction and Dig-ddTUP labeled oligonucleotides. Three primer pairs, E403 and E90as, E91As and E136as, E91Bs and E18as, were used to amplify codons 40-90 of HLA-B related alleles, codon 91 to 136 of HLA-B^*2701-B^*2706 and B^*2708 and codons 91-180 of B^*2707. A total of 11 probes were used to distinguish 8 B^*27 alleles from B^*2701 to B^*2708. 68 AS patients contain 69 B27 alleles because one patient is heterozygous B^*2704/B^*2705. A total of 4 alleles of B^*27 were detected in the AS-patient group. B^*2704 is the most common B^*27 allele in both AS patients and controls with similar frequency, 76.8% and 71.4%, respectively. We found a high proportion of B^*2705 in both AS patient (20.3%) and control (28.6%) groups. Although the control group is quite small we are still able to deduce that B^*2704 and probably also B^*2705 seem to be associated with AS in Shanghai area patients We also found one AS allele typed as B^*2707. Interestingly, for the first time we detected B^*2706 in an AS patient, which would argue against a protective effect of B^*2706 on AS susceptibility in Shanghai Chinese. The conclusion from this study is that the distribution of B^*27 alleles is not significantly different between AS patients and controls. Expanded numbers of AS patients and especially of healthy controls in different ethnic groups will be necessary to assess the contribution of different B27 subtypes to AS susceptibility.     

HLA-B27等位基因和亚型与强直性脊柱炎关系研究进展

大量的研究证明,强直性脊柱炎(AS)是与人类白细胞抗原(HLA)相关性最强的疾病。AS的发病与HLA-B27阳性密切相关,并与B7、B13、B40等几个等位基因有一定关系。HLA-B位点有42个等位基因,其中HLA-B27具有高度多态性,含有22个以上的亚型,不同亚型的碱基序列间只有个别差异。B27亚型在AS患者中的分布因地区和种族上的差别而不同,在中国主要以B2704和B2705为主,但以B2705分布最广。这几年大量的人B27转基因鼠实验证明AS与B27的关联性。     

少儿强直性脊柱炎与幼儿类风湿性关节炎HLA-B27亚型的鉴别诊断

目的：探讨HLA－B27等位基因亚型与少年强直性脊柱炎和幼年类风湿性关节炎的关联。方法：用PCR－SSP方法对74人HLA－B27等位基因亚型进行研究，其中少年强直性脊柱炎32例，幼年类风湿性关节炎28例，5个家系中患者的父亲或母亲5例，正常对照组9例，并进行关联分析。结果：本组人群的HLA－B27等位基因由HLA－B*2704、*2705、*2702、*2707 4种亚型组成，其中少年强直性脊柱炎患者HLA－B27等位基因亚型频率为B*2704 56.25%、B*2705 40.63%、B*2702 3.13%；幼年类风湿性关节炎HLA－B27等位基因亚型频率为B*2705 60．7％、B*2704 28．57％、B*2702 3．57％及B*2707为7．14％；少年强直性脊柱炎与幼年类风湿性关节炎结果比较，HLA－B*2704基因频率在少年强直性脊柱炎组高于幼年类风湿性关节炎组（RR＝3．21，P＜0．05）。结论：少年强直性脊柱炎与HLA－B*2704等位基因亚型关联。对HLA－B27等位基因亚型的检测可成为少年强直性脊柱炎和幼年类风湿性关节炎鉴别诊断中一个有价值的实验指标。     

Prevalence of HLA-B*27 subtypes in the Tamil population of India with Ankylosing spondylitis and its correlation with clinical features

IntroductionHLA-B*27 is strongly associated with Ankylosing spondylitis (AS). Its subtypes show considerable geographic and ethnic difference. The main aim of this study was to assess the frequency of subtypes of HLA-B*27 in the Indian Tamil AS patients.Methods and materialsAdult AS patients positive for HLA-B*27 were considered for the study. The high-resolution typing to define HLA-B*27 subtypes were done using Invitrogen B kits from One Lambda (SeCore® Sequencing Kits, Thermo Fisher, United States).Results and conclusionPrevalence of subtypes identified were HLA-B*27:04 (52.2%), HLA-B*27:05 (41.6%), HLA-B*27:07 (3.5%) and HLA-B*27:02 (2.7%). All subtypes showed disease predisposition for males. The most common extra articular manifestation seen was enthesitis in HLA-B*27:04 and HLA-B*27:05. Uveitis was mainly associated with HLA-B*27:05 and dactylitis with HLA-B*27:04. A significant peripheral joints involvement for female and axial joint involvement for males was seen in HLA-B*27:04. Our study establishes the prevalence of HLA-B*27 subtypes and the associated clinical phenotypes among the Indian Tamil population. Considering the variability of presentation, organ involvement, and disease course in different subtypes and across ethnicities it is critical to define these associations in the ethnic populations we treat for their appropriate care considering the significant negative health and socioeconomic effects of AS.     

HLA-B27 polymorphism in patients with juvenile and adult-onset ankylosing spondylitis in Southern China

Abstract
Distribution of B27 subtypes in juvenile and adult-onset ankylosing spondylitis (JAS and AAS) in Southern China was studied. A total of 505 patients belonged to Han population were included (145 JAS and 360 AAS patients), and 1368 healthy individuals were included as controls. Human leukocyte antigen (HLA)-B27 typing was performed by Luminex liquid array combining polymerase chain reaction-sequence specific oligonucleotide probe (PCR-SSOP) and/or serological method. HLA-B27 subtyping was performed by polymerase chain reaction-sequence specific primer (PCR-SSP). The sequence-based typing was performed for the B*2715 samples to verify the PCR-SSP results. HLA-B27 was presented in 453 of 505 patients (89.7%), compared with 74 of 1368 controls (5.41%). B*2704 subtype in AS group was significantly higher than controls and B*2705 subtype significantly lower. B*2715 and B*2702 were found in 1.32% and 0.66% of the B27-positive patients but none in controls, and there was no significant difference between either of them and controls. B27-positive patients were 134 (92.4%) in JAS group and 319 (88.6%) in AAS group. There was no significant difference for B27 subtypes distribution between JAS (B*2704, 05, 15) and AAS (B*2704, 05, 15, 02) groups. The frequency of B*2715 in two groups was 3 (2.24%) and 3 (0.94%), respectively. The onset age of three JAS patients carrying B*2715 was 5, 9 and 13 years old, respectively. Our results suggested that B*2704 was the predominant subtype in AS patients in Southern China. B*2715 was observed in AS group only and slightly more in JAS than in AAS, and the patients carrying this allele tended to have early onset, B*2715 may be disease-association subtype.     

HLA-B27 allele diversity in Indians: impact of ethnic origin and the caste system

HLA-B27 is a serological specificity which encompasses an increasing number of subtypes that show varied racial/ethnic prevalence in the world. Here, data from 5129 Indians (4500 population and caste; 629 tribal) is compiled from the literature. In addition, HLA-B27 subtyping of 58 positive individuals from Maharastra is presented. Analysis revealed an increased B27 antigen frequency among the north Indian groups (>5%) compared to the south Indian groups (<5%). HLA-B27 subtyping identified B*2704 (34.48%), B*2705 (36.2%), B*2707 (15.51%), B*2708 (10.34%) and B*2714 (3.44%) alleles in the population groups from Maharastra, but these differed in their distribution among the caste and tribal groups studied. The study showed that more extensive subtyping in other Indian caste groups will be necessary to resolve the evolutionary implications of HLA-B27 subtypes and their relationship to disease association in the Indian context.     

Susceptibility to ankylosing spondylitis correlates with the C-terminal residue of peptides presented by various HLA-B27 subtypes

Susceptibility to spondyloarthropaties is strongly associated with some HLA-B27 alleles. Evidence suggests a direct pathogenic role for the B27 molecules which possibly present an arthritogenic peptide to the T cells. If this hypothesis is true, B27 subtypes that differ structurally but are disease-associated ought to be capable of presenting such peptide(s), while non-disease-associated ones would not. We have recently described a B27 subtype, B*2709, and shown its absence in ankylosing spondylitis (AS) patients. Here, we show the elution and sequence of peptides from HLA-B*2709 molecules. Similar to other B27 subtypes, these peptides are mainly nonamers with an Arg at position P2. Comparison of the C-terminal anchors of peptides eluted from B*2702 and B*2705 with those eluted from B*2709 reveals that, while B*2702 and B*2705 have a broader specificity, B*2709 molecules appear to only accept C-terminal hydrophobic residues. A common feature shared by the two caucasoid AS-associated subtypes (B*2702 and B*2705) but different from B*2709, is the presence of a Tyr as peptide C-terminal anchor. The substitution of Val for Tyr at the C terminus in one of the eluted peptides greatly reduces the binding to B*2709 molecules. This finding suggests Tyr as a discriminative amino acid allowed at the C terminus of peptides bound to the AS-associated B27 subtypes, but not to those which are not associated with AS.     

HLA-B27-restricted T cells from patients with ankylosing spondylitis recognize peptides from B*2705 that are similar to bacteria-derived peptides

Ankylosing spondylitis (AS) is an inflammatory systemic disease affecting the spine, sacroiliacal and peripheral joints. Although the aetiology of AS remains unknown, the strong association with the HLA-B27 allele might reflect directly a detrimental effect of the HLA-B27 molecule itself, resulting from its potential capability to present 'arthritogenic' peptides to CD8+ T cells. Because some forms of SpA are triggered by enterobacterial infection, such arthritogenic peptides might originate from autologous and/or bacterial proteins triggering cross-reactive CD8+ T cell clones. Intriguingly, two peptides from the second extracellular domain of HLA-B*2705 share sequence homologies with several enterobacterial antigens, exhibit the HLA-B27-binding-motif, and are presented by HLA-B*2705 itself. The objective of this study was to examine the clonal T cell reactivity against these peptides in patients with AS. To this end, we screened peripheral blood lymphocytes (PBL) of 26 patients with AS and 24 healthy donors for TNF-alpha-producing cells using ELISPOT assays. PBL and synovial fluid-derived lymphocytes (SFL) of peptide-responsive patients were then stimulated and cultured with the relevant peptide and control peptides in vitro. Antigen-specific T cell lines (TCL) were identified by standard chromium release assays. Clonal analysis was performed subsequently applying TCRB-CDR3 spectratyping. Among eight peptides tested, only the HLA-B27 168-176 peptide LRRYLENGK was recognized by PBL from B27+ AS patients but not from B27+ healthy controls (P=0.001). LRRYLENGK-specific T cell clones used preferentially the TCRBV5S1 and the BV14 segment. These results suggest that an HLA-B27-derived peptide with homology to bacterial peptides may play a role in AS.     

HLA-B27 polymorphism in Mumbai, Western India

Human leucocyte antigen (HLA)-B27 encompasses an increasing number of subtypes that show diverse racial/ethnic prevalence in the world. One thousand-one-hundred and seventy unrelated individuals from Mumbai, Maharashtra, Western India were typed for HLA-B27 antigen by serological methods. HLA-B27 positivity was confirmed by polymerase chain reaction using sequence specific primers. High-resolution typing using sequence specific primers for HLA-B27 alleles (B*2701 - B*2721) was carried out in 70 HLA-B27-positive individuals. The frequency of B27 ranged between 1.48 and 9.6% among the caste groups studied. HLA-B27 subtyping identified B*2702 (1.43%), B*2704 (14.29%), B*2705 (70%), B*2707 (12.86%) and B*2718 (1.43%), respectively. The findings illustrate substantial genetic variation and heterogeneity within population groups from India. Extensive subtyping in other Indian caste groups will be necessary to resolve the evolutionary implications of HLA-B27 subtypes and their relationship to disease association in the Indian context.     

HLA-B27 polymorphism in the Malays

The frequency of HLA-B27 and its subtypes was determined in 878 Malay subjects. Thirty-five of the subjects typed for HLA-A, -B and -DR were found to be positive for HLA-B27. The frequency of this allele in the Malay population was found to be 3.99%. The subtypes observed and their frequencies are: HLA-B*2704 (19.4%), HLA-B*2705 (5.6%), HLA-B*2706 (72.2%) and HLA-B*2707 (2.8%).     

Large sharing of T-cell epitopes and natural ligands between HLA-B27 subtypes (B*2702 and B*2705) associated with spondyloarthritis

HLA-B*2702 is an ankylosing spondylitis-associated allotype that differs from the more common B*2705 at residues 77, 80, and 81, in the peptide-binding site. The diversity and fine specificity of alloreactive cytolytic T-lymphocyte (CTL) raised against B*2702 were analyzed at the clonal level. Significant crossreaction with B*2705 and B*2709 indicated that the three subtypes share numerous T-cell epitopes. However, some epitopes shared by B*2702 and B*2705 were lost in B*2709, which correlates with weaker association of this subtype to disease. Clonal specificities were donor-dependent, indicating that allo-immunogenicity is variable among individuals. Anti-B*2702 CTL were little affected by single mutations mimicking B*2702/B*2705 polymorphism, but the double mutant at positions 77 and 81 was recognized worse than B*2705, suggesting a compensatory effect of residue 80. Thus, HLA-B27 polymorphism modulated alloreactivity through cooperative and compensatory effects on T-cell epitope structure. Comparison of B*2705- and B*2702-bound peptide repertoires revealed that they overlapped by 73% and 81%, respectively. This was larger than B*2702/B*2705 cross-reaction, indicating that HLA-B27 allospecificity is only partially determined by the nature of peptide repertoires. The large sharing of natural ligands and T-cell epitopes is consistent with a pathogenetic role of B*2702 and B*2705 in spondyloarthritis based on antigen presentation.     

An HLA-B27 polymorphism (B*2710) that is critical for T-cell recognition has limited effects on peptide specificity

Abstract: The B*2710 subtype differs from the HLA-B27 prototype (B*2705) only by having Glu instead of Val at position 152, in the α2 helix of the peptide-binding site. In spite of its structural similarity most allore-active CTL raised against B*2705 fail to cross-react with B*2710. Indeed, of the residues that are polymorphic among HLA-B27 subtypes, the Val> Glu152 change has the greatest influence on HLA-B27 T-cell antigenicity. The molecular basis for this antigenic disparity was analyzed in this study. Sequence analysis indicated that B*2710-bound peptides have very similar motifs to B*2705-bound ones both at the main and auxiliary anchor positions. In addition, most of the individual ligands sequenced from B*2710 were previously found in B*2705. Together these results indicate that both subtypes have largely overlapping peptide repertoires. Molecular dynamics simulations of a common ligand in complex with either B*2710 or B*2705 failed to detect significant conformational changes in the peptidic main chain or in solvent accessibility of the side chains. In addition, modeling of the Val>Glu152 change into the MHC-peptide-TCR structure suggested a direct role of residue 152 in interaction with the TCR. Thus, the large differences in T-cell recognition between B*2710 and B*2705 are not explained by an effect of the Glu152 change on peptide specificity or conformation, but by different direct interactions with the TCR.