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PubMed1994

Progress report on the ASHI/CAP Proficiency Survey Program in Histocompatibility Testing. II. HLA-DR, DQ serologic typing, antibody identification, and B-cell crossmatching. American Society for Histocompatibility of Immunogenetics. College of American Pathologists.

This report summarizes the 8-year experience of the DR survey program designed to evaluate the performance of histocompatibility laboratories in the serologic typing of cell specimens for HLA-DR and HLA-DQ polymorphisms and the HLA class II antibody identification and B-cell crossmatching of serum specimens. The number of participants increased from 45 in 1985 to 214 in 1992. Although the performance criteria are based on laboratory consensus, the availability of DNA typing since 1990 has enabled a critical assessment of the reliability of serologic HLA-DR, DQ typing. The survey results shows that unsplit HLA class II antigens DR1-DR8, DR52/53, and DQ1-3 are generally correctly identified in over 90% of the participating laboratories. DR9 and DR10 have not yet been tested and testing for DQ4 has not yet achieved this level on consensus. In contrast, the assignments of serologic subtypes of HLA-DR and HLA-DQ are less consistent and frequently unreliable. Although the B-cell crossmatches show generally high laboratory consensus rates, the serum screening results show frequently inconsistent results regarding HLA class-II-specific antibody identification.

Antibody Specificity↗
PubMed2003

[Association study on HLA-DP and -DQ allelic polymorphisms and nasopharyngeal carcinoma in the Han nationality in Hunan province].

OBJECTIVE: To investigate whether the polymorphisms of HLA-DPA1,DPB1,DQA1 and DQB1 alleles were associated with nasopharyngeal carcinoma(NPC). METHODS: Eighty-seven NPC patients and 91 normal controls of Han nationality in Hunan province were genotyped for HLA-DPA1, HLA-DPB1,HLA-DQA1 and HLA-DQB1 by PCR/SSO technique. RESULTS: The frequencies of allelic gene DPA1*0201, DPB1*1901 and DQA1*0201 were lower, and of DPB1*0402, DQA1*0101 were higher in patients than in controls; the frequencies of haplotype DPA1*0201-DPB1*1401 and DQA1*0201-DQB1*0201 in patients were lower than those in controls; however, the values of P are not significant after Bonferroni correction(Pc>0.05). CONCLUSION: No significant association between the HLA-DP and HLA-DQ loci and NPC in Han nationality in Hunan province was confirmed.

Adult↗
PubMed1995

Mapping and ranking of potential cytotoxic T epitopes in the p53 protein: effect of mutations and polymorphism on peptide binding to purified and refolded HLA molecules.

In many cancer cells, the p53 gene displays point mutations that result in stabilization and accumulation of the p53 protein. Therefore, p53 peptides could be presented to the immune system by tumor cells; thus, p53 might be a suitable target antigen for developing an immunotherapy against tumors using cytotoxic T lymphocytes (CTL). To map candidate CTL epitopes, we synthesized 150 peptides of 8-11 residues that contained putative anchor motifs required for binding to common HLA class I molecules. They were tested for their capacity to promote the assembly of purified and refolded HLA-A1, A2, B7 and B8 molecules. The following wild-type p53 peptides were found to be reactive with the HLA molecules tested: 196-205 and 226-234 bound moderately to HLA-A1; 25-35, 65-73, 129-137, 187-197, 263-272 and 264-272 bound strongly, and 187-195 and 256-264 moderately to HLA-A2; 26-35, 63-73, 189-197, 249-257 and 321-330 bound strongly to HLA-B7; and 135-143, 210-218 and 375-383 bound weakly to HLA-B8. We also analyzed the effects of p53 mutations occurring naturally in tumors on peptide/HLA assembly. We found substitutions that enhanced, diminished or had no effect on the peptide binding to HLA molecules. Polymorphism at position 72 mainly affected peptide/HLA-B7 binding, the proline allele P72 giving a less-reactive peptide (63-73) than the arginine allele R72. We have ranked potential p53 epitopes according to their reactivity for purified HLA molecules, allowing the selection of appropriate peptides and HLA molecules to attempt CTL induction in vitro.

Amino Acid Sequence↗
PubMed1990

HLA-DQ beta sequence polymorphism and genetic susceptibility to IDDM.

The analysis of HLA-DQ beta nucleotide sequence polymorphism in insulin-dependent diabetes mellitus (IDDM) patients and control subjects suggests a role for the DQ beta-chain in genetic susceptibility. Sequence determination and oligonucleotide hybridization was carried out on enzymatically amplified DNA from various HLA-DR-typed individuals, including the rare class of DR2+ patients. In the analysis of DQ beta variation in DR4, DRw6, and DR2 haplotypes, a correlation was observed between the presence of the negatively charged residue Asp at position 57 and low susceptibility and the presence of an Ala (DR4), Val (DRw6), or Ser (DR2) and higher susceptibility. However, important exceptions to this pattern have been identified in the analysis of heterozygous DR1/4 IDDM patients. In these individuals, susceptibility appears to correlate with specific DR beta l alleles (Dw4) on the DR4 haplotype, rather than with the DQ beta allele (DQB3.2) that contains Ala at position 57. The DQ beta alleles found in some Chinese IDDM patients also proved discordant with the position-57 correlations. Thus, although there is a general correlation between the residue at position 57 of the DQ beta-chain and IDDM susceptibility, these data do not support the notion that Asp 57 confers complete resistance or protection to IDDM. In general, these results suggest that IDDM susceptibility is conferred by specific combinations of DQ beta and DR beta sequences.

Alleles↗
PubMed1998

HLA class II DNA polymorphism in a Moroccan population from the Souss, Agadir area.

HLA DRB1, DQA1 and DQB1 polymorphisms were analyzed by PCR-SSO typing in a sample of the Moroccan population from Souss. Uneven allelic frequency distributions are observed at each locus, with particularly high frequencies for DRB1*0701, DRB1*0301, DQA1*0501, DQA1*0201, and DQB1*0201. Only three haplotypes (DRB1*0701-DQA1*0201-DQB1*0201, DRB1*0301-DQA1*0501-DQB1*0201 and DRB1*11-DQA1*0501-DQB1*0301) account for nearly 50% of the total gene frequencies. A genetic distance analysis reveals that the Moroccan population is close to the Spanish and the Algerians, who live in geographically neighboring areas. However, the Souss population is also characterized by a lower level of genetic diversity compared to other African and European populations from the Mediterranean area. This may be the result of a rapid genetic drift due to their likely geographical and/or cultural isolation.

Alleles↗
PubMed1995

DQCAR microsatellite polymorphisms in three selected HLA class II-associated diseases.

DQCAR is a very polymorphic CA repeat microsatellite located between the HLA DQA1 and DQB1 gene. Previous studies have shown that specific DQCAR alleles are in tight linkage disequilibrium with known HLA DR-DQ haplotypes. Of special interest was the fact that haplotypes containing long CA repeat alleles (DQCAR > 111) were generally more polymorphic within and across ethnic groups. In these latter cases, several DQCAR alleles were found even in haplotypes containing the same flanking DQA1 and DQB1 alleles. In this work, three HLA class II associated diseases were studied using the DQCAR microsatellite. The aim of this study was to test if DQCAR typing could distinguish haplotypes with the same DRB1, DQA1 and DQB1 alleles in control and affected individuals. To do so, patients with selected HLA DR-DQ susceptibility haplotypes were compared with HLA DR and DQ matched controls. This included: Norwegian subjects with Celiac disease and the HLA DRB1*0301, DQA1*05011, DQB1*02 haplotype; Japanese subjects with Type 1 (insulin-dependent) Diabetes Mellitus and the HLA DRB1*0405, DQA1*0302, DQB1*0401 haplotype; and French patients with corticosensitive Idiopathic Nephrotic Syndrome and the HLA DRB1*0701, DQA1*0201, DQB1*0202 haplotype. These specific haplotypes were selected from our earlier work to include one haplotype bearing a short DQCAR allele (celiac disease and DR3,DQ2-DQCAR99) and two haplotypes bearing long DQCAR alleles (Diabetes Mellitus and DR4,DQ4-DQCAR 113 or 115 Idiopathic Nephrotic syndrome and DR7,DQ2-DQCAR 111-121). Additional DQCAR diversity was found in both control and patients bearing haplotypes with long CA repeat alleles. The results indicate that DQCAR typing did not improve specificity in combination with high resolution DNA HLA typing as a marker for these three disorders.

Base Sequence↗
PubMed1988

HLA-A and B polymorphisms predate the divergence of humans and chimpanzees.

Major histocompatibility complex (MHC) glycoproteins bind processed fragments of proteins and present them to the receptors of T lymphocytes. The extraordinary polymorphism of class I MHC molecules in man (HLA-A, B and C) and mouse (H-2 K, D and L) poses many questions concerning their diversification and evolution. Comparison of allelic sequences within a species suggests diversity is generated by the assortment of point mutations into varied combinations by mechanisms of recombination and gene conversion. We have now compared class I MHC alleles in two closely related species: humans (Homo sapiens) and chimpanzees (Pan troglodytes). Chimpanzee homologues of HLA-A, HLA-B and a non-classical gene have been identified. No features distinguishing human and chimpanzee alleles could be found. Individual HLA-A or B alleles are more closely related to individual chimpanzee alleles than to other HLA-A or B alleles. These results show that a considerable proportion of contemporary HLA-A and B polymorphism existed before divergence of the chimpanzee and human lines. The stability of the polymorphism indicates that hyper-mutational mechanisms are not necessary to account for HLA-A, B and C diversity.

Alleles↗
PubMed1990

HLA-DQA2 (DX alpha) polymorphism and insulin dependent diabetes.

A certain HLA-DQA2 locus TaqI fragment, DX alpha"U", has been reported to be associated with insulin-dependent diabetes mellitus (IDDM). Reports of various studies in this vein have ranged from stating that the association of DQA2"U" with IDDM exists even among subjects positive for HLA-DR3 and -DR4 to stating that the association of DQA2"U" with diabetes can be attributed to linkage disequilibrium between the DQA2"U" and some component(s) on the affected haplotypes. Using a synthetic 97-base probe corresponding to a portion of an intron of DQA2, in a Southern blot analysis of IDDM and control subjects from Wisconsin, we were able to confirm the association of DQA2"U" with diabetes. However, among DR3 subjects there was no significant association between DQA2"U" and diabetes (p = 0.26). Although there was a (nonsignificant) association of IDDM with DQA2"U" among DR4-positive subjects (p = 0.14), this can be completely attributed to linkage disequilibrium between DQA2"U" and DQw8. We also sequenced most of the second exon (corresponding to the alpha 1 domain of the DQA2 glycoprotein) from five individuals that were homozygous for either DQA2"U" or DQA2"L." The only polymorphisms observed were a "silent" mutation at position 36 and one example of a difference that would result in a change of amino acid at position 41.

Adult↗
PubMed2003

Association between HLA-DQA1, -DQB1 gene polymorphisms and susceptibility to asthma in northern Chinese subjects.

OBJECTIVE: Human leukocyte antigen (HLA) class II genes, especially HLA-DQ genes, which are highly polymorphic, have been thought to be candidate loci for the etiology of asthma, and shown to be involved in antigenic presentation. This study was conducted to investigate whether susceptibility or resistance to asthma is associated with HLA-DQA1 and DQB1 genes polymorphism. METHODS: Venous blood samples were collected from northern Chinese population with Han ethnic. (1) One hundred and twenty-five unrelated asthmatic individuals and 52 subjects from 12 asthmatic pedigrees. (2) Ninety-six healthy controls without asthma and atopy with the same ethnic. Genomic DNA was extracted using standard phenol-chloroform method. The second exon of HLA-DQA1 and DQB1 genes were amplified by sequence-specific primer-polymerase chain reaction (SSP-PCR) method. All asthmatics had their serum IgE (total and specific) antibody or skin-prick test measured, bronchial reactivity to methacholine (Mch) and bronchial reversibility by beta(2)-agonist evaluated. RESULTS: HLA-DQA1 * 0104 allele and HLA-DQB1 * 0201 allele were significantly higher in asthmatics than those in healthy controls (0.408 vs 0.177, P < 0.01; 0.568 vs 0.198, P < 0.01). Odds ratios (ORs) were 3.203 (95% CI 1.699 - 6.037), 5.328 (95% CI 2.883 - 9.849) respectively. Conversely, HLA-DQA1 * 0301 allele and HLA-DQB1 * 0301 were significantly decreased in asthmatics compared to healthy controls (0.296 vs 0.50, P < 0.01; 0.4 vs 0.563, P < 0.05); Logistic regression analysis showed that HLA-DQA1 * 0104 allele was associated independently with asthma etiology, OR [represented by Exp(B)] was 5.0942 with 95% CI 2.2520 - 21.1813; Spearman's analysis showed that HLA-DQA1 * 0104 allele and HLA-DQB1 * 0201 allele were positively associated with atopy, the correlation coefficient were 0.183 and 0.289 respectively, P < 0.01. By contrast, HLA-DQA1 * 0301 allele was negatively related to atopy, the correlation coefficient was -0.168, P < 0.05; linkage analysis did not support the view that HLA-DQA1/DQB1 genes were linked to asthma with LOD value being 0.72. CONCLUSIONS: HLA-DQA1 * 0104 allele and HLA-DQB1 * 0201 allele were implicated in susceptibility to asthma and atopy, HLA-DQA1 * 0301 allele and HLA-DQB1 * 0301 might be protective factor against asthma. Asthma and atopy are multifactorial disorders, HLA-DQA1 and DQB1 genes are involved in the regulation of immune specific response to common allergen.

Adult↗
PubMed1999

Identification of peptides from autoantigens GAD65 and IA-2 that bind to HLA class II molecules predisposing to or protecting from type 1 diabetes.

Type 1 diabetes is a T-cell-mediated disease in which presentation of autoantigens to CD4+ T-cells is thought to play a crucial role. Polymorphism of HLA class II genes accounts for 50% of the genetic risk of contracting type 1 diabetes. HLA-DQ and -DR molecules predisposing to or protecting from type 1 diabetes have been identified, but the molecular basis controlling these associations is as yet undefined. Apart from distinct thymic selection of autoreactive T-cells by susceptible and protective HLA molecules, exclusive presentation of autoantigenic peptides by type 1 diabetes-predisposing HLA molecules or, alternatively, induction of regulatory T-cells by protective alleles are potential mechanisms for modification of type 1 diabetes risk by HLA polymorphism. As a first step in exploring the role of HLA molecules in autoantigen-specific cellular responses in type 1 diabetes, we have screened peptides covering the sequence of two major autoantigens targeted by humoral and cellular immune responses, GAD65 and islet associated-2 (IA-2), for binding to class II molecules. We developed a sensitive novel competition binding assay allowing us to measure peptide binding on intact cells to 10 HLA-DR and 4 HLA-DQ molecules. For all tested alleles, multiple peptides binding with high affinity were identified. We report clustering of binding peptides in the COOH-terminal regions of GAD65 and IA-2, as well as highly promiscuous binding patterns of some peptides. Our results demonstrate that most peptides derived from the GAD and IA-2 autoantigens can bind to both type 1 diabetes-predisposing and type 1 diabetes-protective HLA molecules, although some exceptions were observed. The binding inventory presented here for GAD and IA-2 peptides can be useful for mapping natural epitopes and predicting peptide-specific responses induced by preventive immunization.

Alleles↗
PubMed1994

Improved risk assessment for insulin-dependent diabetes mellitus by analysis of amino acids in HLA-DQ and DRB1 loci.

Polymorphisms in HLA class II genes have been shown to contribute to susceptibility or protection against insulin-dependent diabetes mellitus (IDDM). In the present study the role of HLA class II haplotypes and the role of DQ alpha Arg52, DQ beta Asp57 and of polymorphic amino acids, located in the antigen-binding groove and the CD4-binding domain of the DR beta 1 chain, were studied in 210 unrelated Caucasian IDDM patients and 205 controls. The results showed that the genotype homozygous for DR beta 1Lys71+, which is in linkage disequilibrium with DQ alpha 1Arg52+ provided a major risk (relative risk, RR = 15.46) for IDDM and that combination of DR beta 1Lys71+/+ with homozygosity for DQ beta qAsp57-/- of the DQ beta 1 chain significantly increased the RR for developing IDDM (RR = 20.41). The DQ alpha 1Arg52(-)-DQ beta 1Asp57+ haplotype in cis or trans position conferred the highest protection against IDDM (RR = 0.08). Our findings confirm that protection against IDDM is provided by HLA-DQ loci but that susceptibility for IDDM is provided by both HLA-DRB1 and DQB1 loci. Our results also provide a new and more specific approach to determine the risk of any random Caucasian individual to develop IDDM. Indeed, increased susceptibility or protection against IDDM can be determined by the rapid and simple typing of DR beta 1Lys71, DQ alpha 1Arg52 and DQ beta 1Asp57 in a random person.

Adolescent↗
PubMed1998

Polymorphism at the HLA-DQ locus determines susceptibility to experimental autoimmune myasthenia gravis.

Studies in myasthenia gravis (MG) patients demonstrate that polymorphism at the HLA-DQ locus influences the development of MG. Several studies using the mouse models also demonstrate the influence of class II molecules, especially the H2-A, which is the mouse homologue of HLA-DQ, in experimental autoimmune myasthenia gravis (EAMG). We used transgenic mice expressing two different DQ molecules, DQ8 (DQA1*0301/B1*0302) and DQ6 (DQA1*0103/B1*0601), to evaluate the role of HLA-DQ genes in MG. These mice do not express endogenous mouse class II molecules since they contain the mutant H2-A beta0 gene. The mice were immunized with Torpedo acetylcholine receptor, and EAMG was assessed by clinical evaluation and was confirmed by electrophysiology. Clinical scores for EAMG were highest in HLA-DQ8 transgenic mice, whereas the scores of HLA-DQ6 mice rarely exceeded grade 1. There was no incidence of EAMG in class II-deficient (H2-A beta0) mice. These results demonstrate that polymorphism at the HLA-DQ locus affects the incidence and the severity of EAMG. The manifestation of susceptibility to EAMG in the context of human class II molecules underscores the important roles of these molecules in the initiation and perpetuation of EAMG.

Animals↗
PubMed1991

Restriction fragment length polymorphism of two HLA-B-associated transcripts genes in five autoimmune diseases.

The restriction fragment length polymorphism of the two human HLA-B-associated transcripts (BATs) genes, BAT1 and BAT2, identifying polymorphic bands of 12, 8, 2.5, and 1.1 kb, and at 3.3, 2.7, 2.3, and 0.9 kb, respectively, was investigated in patients with primary biliary cirrhosis (PBC), systemic lupus erythematosus (SLE), pauciarticular juvenile rheumatoid arthritis (P-JRA), rheumatoid arthritis (RA), and primary Sjögren's syndrome (pSS), and in healthy Danes. The BAT2/RsaI 2.7-kb band fragment was more frequent in PBC, pSS, and SLE than in controls, but the p values did not reach significance when corrected for multiple comparisons. For pSS and SLE, the associations may be secondary to primary associations with HLA-B8 because the BAT2/RsaI 2.3-kb band, which is allelic to the BAT2/RsaI 2.7-kb band, is strongly negatively associated with HLA-B8 and HLA-DR3. The only significance obtained shows that the HLA-B8 frequency is increased in BAT2/RsaI 2.7-kb positive pSS patients as compared to the corresponding controls indicating that the HLA-B8 association may be strongest. No missing or extra DNA fragments were observed in the disease groups when compared with controls indicating that gross deletions or duplications of the BAT1 and BAT2 genes in the patients are unlikely. In conclusions, it cannot be excluded that the BAT2/RsaI 2.7-kb band may contribute to the susceptibility to PBC, pSS, and SLE.

Autoimmune Diseases↗
PubMed1988

Polymorphism of the HLA-DR1 haplotype in American blacks. Identification of a DR1 beta-chain determinant recognized in the mixed lymphocyte reaction.

Mixed lymphocyte typing provides an exquisitely sensitive means of detecting the polymorphism of HLA class II molecules. By using this technique, the differences between divergent human populations become apparent. This study describes a DR1 haplotype commonly present in the American black population. Unlike the Northern European population in which almost all DR1 individuals are DQw1 and type as Dw1 by using mixed lymphocyte typing, approximately 50% of DR1, DQw1 positive American blacks express an undefined Dw specificity. The DR beta polypeptide encoded by a DR1,Dw-cell differs from a previously described DR1,Dw1 beta sequence by two amino acid replacements at positions 85 and 86 in the first domain. One silent nucleotide substitution has also been identified. DQ alpha and beta first domain cDNA sequences from this haplotype are identical with previously described DQ sequences from a DR1,Dw1 cell. This relatively minor change in amino acid sequence of the DR molecule appears to produce the undefined HLA-D specificity in this haplotype. The variant DR1 sequence is shared with a DR beta-chain from the DR2,DwMN2 haplotype suggesting that a gene conversion-like mechanism has generated this difference.

Amino Acid Sequence↗
PubMed1983

Polymorphic restriction endonuclease fragment segregates and correlates with the gene for HLA-B8.

Cellular DNA from HLA-typed individuals was digested with the restriction endonuclease EcoRV. After electrophoresis and transfer to a hybridization membrane, the restriction endonuclease fragments were probed with cDNA carrying the nucleotide sequence encoding a class 1 HLA gene. Polymorphism for presence or absence of various EcoRV fragments was noted in a panel of unrelated HLA-typed individuals. A polymorphic 8.6-kilobase pair EcoRV fragment was found which correlated in the panel with the serologically defined gene HLA-B8. A family study revealed that this fragment segregated with the haplotype carrying the HLA-B8 gene. This fragment may carry the gene for HLA-B8 or it may represent another class 1 gene (or pseudogene) in linkage disequilibrium with HLA-B8.

DNA Restriction Enzymes↗
PubMed2006

Aspartic acid homozygosity at codon 57 of HLA-DQ beta is associated with susceptibility to pulmonary tuberculosis in Cambodia.

After infection with Mycobacterium tuberculosis, clinical disease usually remains latent, contained by the host immune response. Although polymorphisms of HLA loci have been hypothesized to play a major role in the breakdown of latency, a functional link has not been established. Molecular-based HLA-typing methods were used to test the association of sets of HLA alleles encoding an aspartic acid at codon 57 of the HLA-DQ beta-chain (HLA-DQ beta57-Asp) with susceptibility to tuberculosis in a cohort of 436 pulmonary tuberculosis patients and 107 healthy controls from Cambodia. HLA class II null cells were transduced with HLA-DQ beta57-Asp or HLA-DQ beta57-Ala and evaluated for their ability to bind peptides from two immunogenic M. tuberculosis specific proteins, ESAT-6 and CFP-10. In this study, we report a highly significant association between progressive pulmonary tuberculosis and homozygosity for HLA-DQ beta57-Asp alleles. The presence of HLA-DQ beta57-Asp resulted in a significantly reduced ability to bind a peptide from the central region of the ESAT-6 protein. Furthermore, when this peptide was presented by an HLA-DQ beta57-Asp allele, Ag-specific IFN-gamma production from CD4+ T cells from tuberculosis patients was significantly less than when this peptide was presented by an HLA-DQ-beta allele encoding an alanine at codon 57. Multiple genetic loci and ethnic-specific factors are likely involved in the human immune response to tuberculosis. The data presented here provide a functional explanation for a highly significant association between an HLA polymorphism and tuberculosis in a highly characterized group of patients with susceptibility to progressive tuberculosis infection in Cambodia.

Adolescent↗