HLA B27 polymorphism in Western India

We have characterized HLA B27 alleles in a sample population of Maharastra, Western Indians (n = 51), with the aim to investigate the different subtypes present among this population. The study was carried out using polymerase chain reaction with sequence-specific primers (PCR-SSP) and reverse line strip (RLS) techniques. Significant new findings have arisen from this study: B*2704, B*2705, B*2707, B*2708 and B*2714 alleles were found to be present, and two novel B27 alleles, B*2708 and B*2714, were found in this Indian population. In addition, B*2714 was observed in a patient with ankylosing spondylitis. This association has not been previously reported in ethnic groups from India.     

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%).     

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-B*27 typing by PCR—restriction fragment length polymorphism

In this study we describe the use of PCR-RFLP for genotyping HLA-B*27. A 557 bp fragment from HLA-B locus is amplified and subjected to digestion with Sty I. The presence of B*27 is detected on electrophoresis by the appearance of 431+126 bp pattern. The same pattern could be obtained only for the very infrequent allele B*7301. However, this allele was not amplified in the B73 sample tested with the primers and conditions used in this study. Nevertheless, we have designed two PCR-RFLP approaches for separating these alleles. The PCR-RFLP method was tested on a panel of forty-three cell lines and applied to fifty spondyloarthritic patients and one-hundred-eighty healthy subjects. Given its robustness, technical simplicity and cost-effectiveness, we think that this method can be incorporated for routine use in most laboratories     

强直性脊柱炎患者HLA-B27位点等位基因相关抗原的表达

目的：探讨强直性脊柱炎（AS）患者HLA-B27位点等位基因相关抗原的表达。方法：采用补体依赖性微量淋巴细胞毒法检测418例脊柱关节炎（SpAS）患者和30例正常对照HLA-B27相关抗原。结果：418例SpAS患者73例被确诊为AS,Bw6、B27（47）、B27和B7/B27/B73/B81抗原阳性率分别为31%、28%、25%和22%。在AS中,B27阳性组与B27阴性组间有不同分布,两组B27（47）、B27、B7三种等位基因有统计学意义（P〈0.01）。在66例B27阳性组中,除B13与Bw6成负相关外,Bw4与B27（47）、B7与B27之间等均成明显的正相关。结论：在AS患者中,B13与Bw6、B60/61/47/48/81（13）,B7与B27,Bw4与B27（47）,Cw1与B42B45表达联锁失衡,B27并不是AS易感的唯一因素,其他基因位点可能起增强（如Cw1及Cw2）或抑制（如B13）AS发生的作用。     

Ligation based HLA-B*27 typing

We have established a ligation based typing method to detect HLA-B*27 alleles at the DNA level. The method requires amplification of exon 2 of the HLA-B locus from genomic DNA by the polymerase catalyzed chain reaction (PCR) using group specific primers. An aliquot of the PCR amplification product, heat stable ligase and a pair of oligonucleotide probes, designed to hybridize adjacently to HLA-B*27 specific sequences of the amplified DNA are subsequently thermocycled. If the probes are perfectly complementary they become ligated otherwise they stay separated. The ligation of probes can be detected through their different labels by an enzyme linked immunosorbent assay (ELISA). Ligation based detection of beta-actin sequences which have been co-amplified serves as positive control for each PCR reaction. We observed complete concordance when typing 76 HLA-B*27 positive and 107 HLA-B*27 negative individuals either by serology or by the ligation based approach. We conclude that ligation based typing is a reliable tool for the DNA based detection of HLA-B*27 alleles. The procedure allows automation to a large extent and should be easily applicable to the typing of other HLA-class I alleles.     

Modulation of peptide binding by HLA-B27 polymorphism in pockets A and B,and peptide specificity of B*2703

The results in this study address three aspects of peptide binding to the disease-associated antigen HLA-B27 and its modulation by polymorphism: the contribution of major anchor residues 2 and 9, the role of pocket B polymorphism in modulating peptide specificity, and the binding properties of B*2703, a subtype not found to be associated with spondyloarthropathy. Synthetic analogs of peptides naturally presented by B*2705 were used to demonstrate that residue 2 is essential, since Ala2 analogs bound marginally to B*2705, but the specificity of B*2705 for Arg2 is not absolute, and show that the contribution of basic residue 9 to binding was significant, but less than Arg2. The effect of single mutations in the B pocket was to decrease or - with the Glu > Met-45 mutation - totally shift pocket B specificity for Arg2 towards other residues at this position. This was shown by quantitating the relative binding of Gln2 and Ala2 analogs, and by pool-sequencing of the peptides bound in vivo to these mutants. Peptides naturally presented by B*2705 apparently bound with a lower affinity to pocket A variants with altered hydrogen bonding to the peptide N terminus, including B*2703. Binding of peptide analogs with changes at positions 2 or 9 suggested that in B*2703 pocket A, interactions are weaker and pocket B interactions are stronger than in B*2705. This can be explained by the effect of the unique His59 change in B*2703 in both pockets. Thus, B*2703 is probably the HLA-B27 subtype with the most stringent specificity for the Arg2 peptide motif.     

细胞因子对HLA-B27启动子的调节作用及其在强直性脊柱炎发病机制中的意义

目的： 构建含HLA-B27启动子的HeLa稳定转染细胞株，观察7种细胞因子对HLA-B27启动子及其上游NF-κB及ISRE顺式作用元件活性的调节作用，探讨强直性脊柱炎（AS）等B27相关疾病的发生机制。方法:转染HeLa细胞，抗生素筛选单克隆构建含HLA-B27启动子的稳定转染细胞株。构建HeLa-B27稳定细胞株和HeLa-NF-κB稳定细胞株，在瞬时转染pISRE-luc的HeLa细胞中加入白细胞介素1α（IL-1α）、 白细胞介素1β（IL-1β）、 肿瘤坏死因子α（TNF-α）、干扰素α（IFN-α）、干扰素β（IFN-β）、 干扰素γ（IFN-γ）和转化生长因子β（TGF-β），观察7种细胞因子对B27启动子及其上游NF-κB和ISRE作用元件的调节作用。另外在HeLa-B27 稳定细胞株培养液中同时加入3种细胞因子单克隆抗体和相应细胞因子，观察其对启动子活性的调节作用。结果:TNF-α、IFN-α、IFN-β 和 IFN-γ 均能明显增强HeLa细胞B27启动子活性。细胞培养96 h 后，IFN-β为最强的启动子诱导剂（5.4倍，P<0.05）；细胞培养8 h 内，TNF-α、IL1-α 和 IL1-β,可诱导NF-κB的活性增加30倍左右（P<0.05），IFN-α 和IFN-β 可诱导ISRE的活性增加12倍左右（P<0.05），抗TNF-α 抗体对于I类IFN 增加的B27 启动子活性没有明显的抑制作用。结论：TNF-α和IFN 可通过结合于B27 启动子中各种转录因子结合元件调控HLA-B27启动子的转录活性，IFN-β 可能在强直性脊柱炎等B27 相关的脊柱关节病的发病机制中起着重要作用。     

HLA-B27 polymorphism and worldwide susceptibility to ankylosing spondylitis

HLA-B27 is strongly associated to ankylosing spondylitis (AS) and represents a family of eleven B27 alleles (B*2701–11). Our aim was to analyze the distribution of B27 subtypes by PCR/SSOP and genomic sequencing in a large group of populations ( n =17). 711 B27-positive samples from Caucasoid, Asian, African, Amerindian and Polynesian populations were selected to ascertain transracial gene mapping of the B27 subtypes. 476 of these were AS patients, chosen to investigate the contribution of B27 alleles to AS susceptibility. Some significant new findings have arisen from this study: 1) B*2705 was the predominant subtype in circumpolar and subarctic areas. B*2702 was found to be practically restricted to Caucasian populations, showing a higher frequency in Middle-East (Jews) and North Africa (Arabs/Berbers) groups. 2) B*2703 appears associated with AS in Western Africans. This is of remarkable interest since it was suggested that B*2703 would be negatively disease-associated. 3) Although B*2706 appears negatively associated with AS in Thais, we identified two patients from northern China carrying it. This may be a reflection of a disease heterogeneity and could indicate that more than one pathogenic agent can be involved in AS. B*2709 has been recently described as negatively associated with AS in Sardinians. The molecular changes His 114Asp (B*2706) and Asp 116His (B*2709) could modify the genetic susceptibility to AS.     

New insights regarding HLA-B27 diversity in the Asian population

A polymerase chain reaction-sequence-specific primer (PCR-SSP) method which distinguishes all B27 alleles described at present (B*2701-23) has been developed. The distribution of B27 alleles was characterised in six different Asian populations. HLA-B*2705, 02, 04, 07, 22 (formerly B*2706) subtypes found in Asian populations differ in their ethnic distribution, which may be the result of different genetic and geographic origins. Furthermore, two novel B27 alleles were found in this study. B*2714 was identified in two Siberians, one of whom was a patient with ankylosing spondylitis. B*2715 was found in two patients with ankylosing spondylitis in Thais. These associations have not previously been reported in either ethnic group.     

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。     

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.     

外周血T淋巴细胞HLA-B27检测辅助诊断强直性脊柱炎

目的 探讨外周血T淋巴细胞HLA-B27和血清多项免疫指标检测对强直性脊梓炎(AS)的辅助诊断价值.方法 采用流式细胞仪对52例疑似AS患者外周血T淋巴细胞HLA-B27表达进行检测,结合临床资料对AS作出诊断;对其中37例男性病例血清免疫球蛋白IgG、IgA、IgM,补体C3、C4及C反应蛋白(CRP)含量进行免疫比浊法测定.结果 52例疑似AS患者共检测出 HLA-B27+13例(男性12例,女性1例),确诊AS患者12人(男性患者11人,女性1人),包括男性HLA-B27+AS患者9例(最小年龄12岁,最大58岁),男性HLA-B27-AS 2例(分别为20岁和78岁),女性HLA-B27-AS 1例为(9岁),男性AS确诊患者的HLA-B27阳性率为82%.除补体C3外,男性AS组IgG、IgA、IgM、C4及CRP均较男性非AS组高(P＜0.05).结论 AS患者体液免疫功能明显活跃,HLA-B27检测有助于临床资料疑似病例的AS诊断.     

HLA-B27, antinuclear antibodies and drug-induced agranulocytosis

Summary Eight female patients with drug-induced agranulocytosis (five patients with definite seropositive rheumatoid arthritis (RA), three patients with upper respiratory infections) were studied for the presence of HLA-B27 and antinuclear antibodies (ANA). Five of eight patients were found to be HLA-B27 positive and all RA patients had ANA in their serum. The frequency of HLA-B27 and ANA was found to be significantly different from control groups. It is concluded that the occurrence of HLA-B27 in female patients with seropositive RA (especially in those with ANA) and of HLA-B27 alone in other individuals could reflect an increased risk for drug-induced agranulocytosis.We are grateful to Dr. D. Rusch for his support by performing the statistical calculations     

The pathogenesis of HLA-B27 associated arthritis: lessons from the B27 crystal

The most remarkable association between a major histocompatibility complex antigen and disease susceptibility - HLA-B27 and seronegative spondyloarthropathies, particularly ankylosing spondylitis - was discovered 20 years ago. During the two intervening decades advances in basic immunology and molecular biology have not only revealed the biosynthesis and structure of HLA-B27 but also given clues to the basic function of this molecule, the presentation of allele-specific peptides to CD8+ cytotoxic T cells. The recently reported three-dimensional structure of HLA-B27 and the identification of self-peptides bound to this major histocompatibility complex class I antigen can be viewed as a landmark in the understanding of the pathogenic role of HLA-B27. Based on crystallographic evidence, a peptide-binding motif can be postulated that should allow identification of HLA-B27 complexed peptides which may trigger an immune reaction causing arthritis.Abbreviations CTL CD8⁺ cytotoxic T-cells - TCR T-cell receptor - ₂m ₂-microglobulin - LMP low molecular mass polypeptide Correspondence to: H. Kellner     

Chemical reactivity of an HLA-B27 thiol group

Techniques have been developed to measure the reactivity of free thiols in the HLA class I antigen-binding cleft. HLA-B27, which sequencing predicts has a free cysteine at position 67, reacts rapidly with the positively charged thiol reagent monobromotrimethyl-ammoniobimane bromide (qBBr) to give products which are identifiable by isoelectric focusing. HLA-B38, B39, B64 and B65, all of which have a similar Cys 67, react less strongly. Several other class I molecules, notably HLA-C antigens, are reactive in this system, and it may be capable of recognizing subtypes such as A*0207 which also carry free cysteine. The accessibility of thiol to qBBr depends both on the chemistry of the class I molecule and other factors in the cell. Two human cell lines which are known to carry identical B27 genes but do not present the same peptides, differ considerably in the accessibility of their B27 thiol. Evidence from mouse cells transfected with mutant B27 genes suggests that a unique lysine at position 70 in the wild-type molecule increases reactivity to thiol-reactive metabolites. The failure of B27 to give a complete reaction with qBBr in our model systems suggests that it can exist in more than one chemical form. This may leave the molecule susceptible to oxidation, causing errors in T cell recognition and an exaggerated inflammatory response.     

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.     

Non-conventional forms of HLA-B27 are expressed in spondyloarthritis joints and gut tissue

ObjectivesHuman leukocyte antigen (HLA)-B27 (B27) is the strongest genetic factor associated with development of Ankylosing Spondylitis and other spondyloarthropathies (SpA), yet the role it plays in disease pathogenesis remains unclear. We investigated the expression of potentially pathogenic non-conventional heavy chain forms (NC) of B27 in synovial and intestinal tissues obtained from SpA patients. We also determined the presence of NC-B27 in joints, lymphoid and gastrointestinal tissue from B27 transgenic (TG¹) rats with M.tuberculosis-induced SpA.MethodsExpression of NC-B27 in human SpA joints and gut and in (21-3 × 283-2)F₁ HLA-B27/Huβ2m rat tissue was determined by immunohistochemistry, flow cytometry and confocal microscopy analysis using HC10 and HD6 antibodies.ResultsBoth HC10- and HD6-reactive HLA molecules were present in synovial tissue from SpA patients. Both NC-B27 and KIR3DL2, a ligand for NC-B27, were expressed in inflamed terminal ileal tissues in patients with early SpA. Infiltrating cells in inflamed joint tissues isolated from B27 TG¹ rats expressed high levels of NC-B27. NC-B27 were also expressed in joint-resident cells from ankle and tail joints of B27 TG¹ rats prior to clinical arthritis. The expression of NC-B27 on B27 TG¹ rat CD11b/c⁺, CD8α⁺, cells from spleens and LNs increased with animal age and disease progression.ConclusionsNon-conventional HLA class 1 molecules are expressed on resident and infiltrating cells in both synovial and GI tissues in human SpA. NC-B27 expression in joints and lymphoid tissues from B27 TG¹ rats prior to the onset of arthritis is consistent with the hypothesis that they play a pathogenic role in SpA.