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Results for “HLA polymorphism”

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At least 649 records · Page 36Linked to original sources

PubMed1995

Inhibition of gamma delta T cell recognition by receptors for MHC class I molecules.

NK cells have receptors for MHC class I molecules that inhibit cytotoxicity against target cells. We show that recognition of gamma delta CTL is negatively regulated by receptors for MHC class I molecules. Cytolysis of C1R cells by gamma delta CTL clones was inhibited by the expression of polymorphic HLA class I molecules on target cells and was restored by blocking with anti-HLA class I mAb, suggesting the presence of inhibitory receptors for HLA class I molecules. The receptors for HLA class I molecules on gamma delta T cells were heterogenous. The immune responses to various Ags may be regulated via these inhibitory receptors on T cells and NK cells.

Clone Cells↗

PubMed1994

[Genetic polymorphism of the HLA system in Komi and Komi-Permyaks].

High frequencies of HLA-A2, -A3, -A9, -B7, -B13, -Bw35, and -Dw3 antigens were found in Sysolian and Udorian Komi (from Vizinga and Koslan, respectively), as well as in Zyuzdian Komi-Permyaks. In some populations, high frequencies of HLA-A10, -A28, -B21, -B27, and -B40 antigens were also found. Similarity in both gene frequency patterns and heterozygosity level was noted between these populations and the population of more western European regions, as well as Finno-Ugric nations. Frequencies of some alleles, e.g., HLA-B8 -B12, -B16, and -B18, were found to be intermediate between the corresponding estimates for Mongoloids and Caucasoids. The Mongoloid influence on the gene pool is expressed in increased HLA-B27, -B40, -Cw2, -Cw3, and -Cw4 frequencies. The frequencies of HLA-A3, -A28, -B7, -B13, and -B35 antigens are higher, and that of HLA-B5 is lower, than the respective frequencies in both Caucasoids and Mongoloids. This reflects the specificity of the ancestral group, whose peculiarities cannot be attributed exclusively to the results of Caucasoid-Mongoloid intermixing. The high level of genetic differentiation of Komi ethnographic groups (F st = 0.0188 +/- 0.0045) is emphasized. The characteristics of distribution of HLA antigens and haplotypes are explained in terms of the ethnogenesis of the Komi; markers for their constituent ethnic components were found.

Asian People↗

PubMed1993

Immunobiology of the human placental trophoblast.

Trophoblastic cells use several biological strategies to protect the embryo from potential immunological attack by the mother. The most important are the absence of major histocompatibility antigens, the presence of unique non-polymorphic HLA molecules (HLA-G), and the expression of complement regulatory proteins. The role of these factors is analysed in the light of recent studies.

Abortion, Habitual↗

PubMed2000

The down-regulation of HLA-DM gene expression in rheumatoid arthritis is not related to their promoter polymorphism.

HLA-DM molecule, a class II-like heterodimer, is a critical factor of HLA class II-dependent Ag presentation. It acts as a molecular chaperone and also functions as a peptide editor favoring the presentation of high-stability peptides. Thus, it appears to skew the peptide repertoire presented to T cells. Variation in HLA-DM expression has considerable effect on Ag presentation and regulation of these genes is likely to be a prerequisite to prevent autoimmunity. In this study, rheumatoid arthritis (RA) was chosen as a model of human autoimmune disease since its genetic susceptibility is known to be associated with the HLA-DR and -DM components. We described a limited nucleotide polymorphism in the HLA-DM promoters with functional impact on basal transcriptional activity and IFN-gamma induction as assessed in vitro. However, no difference of allele frequencies was found between controls and RA patients. Despite of this lack of association, expression of HLA-DM molecules was also investigated. Interestingly, an underexpression of HLA-DM transcripts and protein was shown in peripheral blood B cells from RA patients compared with controls or inflammatory arthritis patients. This underexpression does not affect HLA-DR genes and is responsible for a decrease of the DM:DR ratio in RA patients. This specific HLA-DM down-regulation is likely to have important consequences on Ag presentation and could participate in the autoimmune process in RA.

Arthritis, Rheumatoid↗

PubMed1985

Androgenetic origin of African complete hydatidiform moles demonstrated by HLA markers.

The polymorphism of HLA antigens was used as a marker to investigate the genetic origin of hydatidiform moles in Senegal. An androgenetic etiology was demonstrated. When both parents shared HLA antigens a preferential inheritance in the mole of the shared specificities was observed. This relative compatibility of the molar conceptus with the mother may be an element of the process that prevents its early rejection.

Female↗

PubMed1996

Putative linkage between HLA class I polymorphism and the susceptibility to malignant melanoma.

Human leukocyte antigen (HLA) frequencies in 67 melanoma patients were compared to 120 controls in Japan. The frequency of HLA-B13 was increased in melanoma patients compared to controls and was particularly common in nodular melanoma HLA-B61 was decreased in melanoma patients. Almost 50% of acral lentiginous melanoma patients expressed HLA-B51 compared to 0% of nodular melanomas.

Asian People↗

PubMed1995

Lack of association between HLA class II polymorphisms and essential hypertension in a Belgian population.

The aim of the present study was to investigate whether the HLA class II polymorphisms contributes to the susceptibility to essential hypertension in the Belgian population. For this purpose we studied 120 hypertensive patients and 168 normotensive controls by means of a PCR-SSO assay. No significant difference in allele and genotype frequencies of the DRB and DPB1 loci could be found between the two groups. We concluded that essential hypertension as a multifactorial and heterogeneous disease cannot be associated with one of the HLA class II DRB and DPB1 alleles in Belgian patients.

Adult↗

PubMed2006

[The genetic polymorphism of HLA-DQA1 and HLA-DQB1 genes of Chinese Han population in Jiangsu area is studied by PCR-sequence-based typing].

OBJECTIVE: To investigate the polymorphism of HLA-DQA1 and DQB1 genes of Han population in Jiangsu of China. METHODS: The alleles and haplotypes frequencies of HLA-DQA1 and DQB1 genes in 100 unrelated healthy individuals were analyzed by using polymerase chain reaction-sequence-based typing (PCR-SBT). RESULTS: Among the 7 DQA1 alleles detected, the most common allele was DQA1*0301/02/03 with a frequency of 29.5%, which was followed by DQA1*0501, DQA1*0102 and DQA1*0201 with frequencies of 18.5%, 17.0% and 12.5%, respectively. Of the 13 DQB1 alleles detected, DQB1*0201/02 allele (21.5%) was the most frequent allele, followed by DQB1*0301/09 (14.5%), DQB1*0303 (13.5%) and DQB1*0603 (11.5%). The most common DQA1 vs DQB1 haplotype was DQA1*0301/02/03 vs DQB1*0303 with a frequency of 12.5%, which was followed by the DQA1*0201-DQB1*0201/02 (10.5%),DQA1*0501-DQB1*0201/02 (9.5%) and DQA1*0501-DQB1*0301/09 (7.0%). CONCLUSION: The distribution of HLA-DQ alleles and haplotypes in Jiangsu Han population shares some genetic characteristics with other population in northern of China, but has its own characteristics. The data will provide useful information for anthropology, organ transplantation and disease association studies.

Adult↗

PubMed1994

Restriction fragment length polymorphisms in HLA-DR4-DQ3 haplotypes associated with rheumatoid arthritis.

Restriction fragment length polymorphism (RFLP) patterns were studied in serologically confirmed DR4-DQ3 positive patients with rheumatoid arthritis by Southern blot analysis using full length cDNA probes specific for DRB, DQA and DQB hybridized with genomic DNA digested with informative restriction endonucleases. The RFLP patterns correlated with serology confirming all patients to be DR4+ve. The DQB1*0302 (DQ8) allele identified by 12.0kb BamHI, 3.3kb Hind III and 1.8kb Taql fragments was present in all patients suggesting them to be DR4-DQB1*0302. Hybridization of Taq 1 and PVU II digested genomic DNA with DQA cDNA probe revealed four informative RFLP patterns. While three of them correlated with known DR4 subtypes, one was a new polymorphism observed specifically in Indian patients with rheumatoid arthritis. The study further indicated that two of the several known subtypes of DR4, viz., DRB1*0401-DW4-DQB1*0302 and DRB1*0404-DW14-DQB1*0302 may be implicated in susceptibility to rheumatoid arthritis in the Indian population.

Arthritis, Rheumatoid↗

PubMed1990

Polymorphism of HLA-DR2,DQw1 haplotypes in Asian Indians.

We examined the polymorphism of DR2,DQw1 haplotypes in Epstein-Barr virus-transformed B-lymphoblastoid cell lines (HTCs) and unrelated (32 Canadian Caucasians and 24 Asian Indians) individuals by restriction fragment length polymorphism (RFLP) and oligonucleotide typing. The data demonstrate that three subtypes of DR2,DQw1 haplotypes, DRw15(B1.1501).DQw6a(A1.0102,B1.0602),DRw15(B1.1502). DQw6b(A1.0103,B1.0601), DRw16(B1.1601).DQw5(A1.0102,B1.0502) are present in HTCs and Canadian Caucasians. Of these, DRw15(B1.1501).DQw6a (A1.0102,B1.0602) haplotype was present in majority (81.3%) of Caucasians. Among Asian Indians, this haplotype was present only in one DR2,DQw1-positive individual. In addition, three new haplotypes representing different combinations of DRB1, DQA1 and DQB1 genes were demonstrable in Asian Indians. These new haplotypes are DRw15(B1.1501).DQw6b(A1.0103,B1.0601),DRw15(B1.1501). DQw5(A1.0102,B1.0502), and DRw15(B1.1501).DQw6c(A1.0102, B1.0601). The most frequent haplotypes among Asian Indians were DRw15(B1.1502).DQw6b(A1.0103,B1.0601) and DRw15(B1.1501). DQw6b(A1.0103,B1.0601). The distribution of subtypes of DR2,DQw1 haplotypes in Asian Indians was significantly different from that in Canadian Caucasians. The results in the present study have important implications for HLA and for HLA-disease associations.

Asia↗

PubMed2002

HLA class I polymorphism has a dual impact on ligand binding and chaperone interaction.

This article will describe coordinated analyses of how amino acid substitutions in the HLA class I antigen binding groove modify chaperone interaction and peptide ligand presentation. By parallel testing of ligand presentation and chaperone interaction with a series of natural HLA-B subtypes, this study has discovered that position 116 of the HLA-B15 class I heavy chain is pivotal in both peptide selection and control of interaction between the assembly complex and the class I heavy chain. Correlated with these qualitative differences in peptide selection and chaperone association are quantitative differences in the expression levels of the HLA molecules at the cell surface. These parallel studies, therefore, demonstrate that particular HLA class I polymorphisms can simultaneously influence ligand presentation and interaction with intracellular chaperones.

HLA-B Antigens↗

PubMed2006

HLA class II polymorphism: protective or risk factors to breast cancer in Tunisia?

HLA system plays a key role in the tumor cells' escape from immune surveillance. Herein is the first report on the correlation of the susceptibility to breast cancer with HLA class II markers in Tunisia. Molecular typing of HLA-DRB1 and -DQB1 loci was undertaken for 70 Tunisian female patients. Comparison of allele and haplotype distribution between patients and 70 female control subjects reveals a negative association between HLADRB1* 07-DQB1*02 and the incidence of breast cancer in the Tunisian population.

Adult↗

PubMed2001

[Investigation of the polymorphism of HLA-DQCAR microsatellites in the healthy and pulmonary tuberculosis in Hunan Hans].

OBJECTIVE: To observe HLA-DQCAR microsatellite distribution and the association of this gene with pulmonary tuberculosis in Hunan Hans. METHODS: The polymorphism of HLA-DQCAR microsatellite was analyzed by electrophoresis on a 8% denaturing polyacrylamide gel. The length of its alleles was determined by sequencing. RESULTS: Ten alleles, DQCAR101, 103, 105, 107, 111, 113, 115, 117, 119 and 121, were found in 68 Hunan healthy Hans, but the frequencies of them were different. In addition to the above-mentioned alleles, DQCAR 99 and 109, were also found in 79 pulmonary tuberculosis patients in Hunan Hans. This results as well showed that DQCAR115 allele was significantly associated with pulmonary tuberculosis in Hunan Hans (RR = 2.12, Pc < 0.05). CONCLUSIONS: The frequency of DQCAR alleles is of great polymorphism. DQCAR115 is significantly associated with pulmonary tuberculosis in Hunan Hans.

Adolescent↗

PubMed1993

Antigen processing gene polymorphisms in HLA-DR2 multiple sclerosis.

The association between multiple sclerosis (MS) and alleles of the HLA class II genes indicates that at least one MS susceptibility gene is linked to the HLA class II region. However, the actual locus responsible has not been precisely identified. The recent cloning of new genes involved in antigen processing that map within the HLA class II region led us to investigate--using the restriction fragment length polymorphism (RFLP) technique and sequence-specific oligonucleotide analysis--whether these genes might play a role in conferring susceptibility to MS. We studied large multifunctional protease (LMP) 2 and 7 and transporter associated with antigen processing (TAP) 1 and 2 gene polymorphisms in 60 HLA-DR2 MS patients and 60 HLA-DR2 healthy subjects and found no specific or preferential RFLP patterns or coding sequence variants in the patient group. Our data do not support a role for these genes in MS susceptibility.

Adult↗

PubMed1992

HLA-DR,DQ sequence polymorphisms in Polynesians, Micronesians, and Javanese.

The origins of the Polynesians remain an enigma. Linguistic reconstructions of proto-Austronesian languages suggest a shared origin for Polynesians, Micronesians, and Javanese with dispersal from northern Borneo and Sulawesi. Analysis of 810 chromosomes for nucleotide sequence polymorphism at HLA-DRB1, DRB3, DRB5, DQA1, and DQB1 loci in Polynesian (Rarotonga, Western Samoa, and Niue), Micronesian (Nauru and Kiribati), and Javanese populations showed virtually no overlap of HLA class II haplotypes between contemporary Polynesians and Javanese. Further, there were marked differences in population distributions of some HLA-DRB1 alleles that could not be distinguished in earlier serologic or restriction fragment length polymorphism (RFLP) studies, e.g., for DR12, DRB1*1201 had a frequency of 15%-30% in Polynesians (1% in Micronesians and Javanese), whereas DRB1*1202 had a frequency of 28%-38% in Micronesians and 51% in Javanese (1% in Polynesians). A novel DR6-related allele, DRB1*1408, was found in all three Polynesian study populations. The Polynesian HLA class II genetic repertoire is not readily derived from the island Southeast Asian gene pool.

Adult↗

PubMed1989

Characterization of the class I HLA 9.2-kb PVU II restriction fragment length polymorphism. Linkage to HLA-A and lack of disease association.

The strongest reported association between a class I HLA allele and disease is that of HLA-B27 with ankylosing spondylitis (AS). However, it has not been shown whether B27 is the gene that predisposes to the development of AS or if it is merely linked with the disease-susceptibility locus. Furthermore, if B27 itself is the disease-susceptibility gene, there may be epistatic loci that also contribute to the development of AS or modify its clinical manifestation. A class I HLA 9.2-kb Pvu II restriction fragment was recently identified, which, when present in a B27-positive individual, further increased the relative risk for developing AS (from 119 to 297). This study was therefore designed to confirm the association between AS and this restriction fragment length polymorphism (RFLP) and to map the location of this fragment in the genome. The data presented here suggest that the class I HLA 9.2-kb Pvu II RFLP represents a Pvu II polymorphism at the 5' end of the HLA-A locus that is tightly linked with both HLA-A3 and A9 alleles. However, there is no association between this RFLP and AS in a population of patients living in Baltimore.

Arthritis, Reactive↗

PubMed2005

TAP1 and TAP2 gene polymorphisms and HLA-TAP haplotypes in Koreans based on 90 families.

We have investigated the polymorphism of TAP genes and the distribution of human leukocyte antigen (HLA)-TAP haplotypes in 90 Korean families (180 parents and 233 children), previously typed for HLA class II alleles. TAP1 (codons 333 and 637) and TAP2 (codons 379, 565, 577, 651, 665, and 687) typings were carried out by use of polymerase chain reaction-restriction fragment length polymorphism method. For TAP1, four alleles (gene frequency: A 81.9%, B 15.0%, C 2.5%, D 0.5%) and for TAP2, nine alleles (A1 31.7%, A2 14.2%, B 32.5%, Bky2 6.1%, C 6.9%, D 2.5%, E 3.9%, G 0.8%, and H 1.4%) were detected. Sixteen different TAP1-TAP2 haplotypes were observed with frequencies > 0.5%, and we found that significant linkage disequilibrium was present between TAP1 and TAP2 loci (p < 0.001). When HLA-DRB1-DQB1 haplotypes were extended to TAP1 and TAP2 loci, much diversification of haplotypes was observed: 26 different DRB1-DQB1 haplotypes (frequencies > 0.8%) formed 90 different extended haplotypes. Eight recombinant haplotypes between DQB1 and DPB1 loci were observed, and most (seven of eight) of the recombinations occurred between TAP2 and DPB1 loci. These results add more evidence to the view that recombination hot spot is present within and around TAP gene region.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2004

Multiplexed analysis of polymorphisms in the HLA gene complex using bead array chips.

A novel custom bead array technology is introduced, and it is applied to multiplexed analysis of highly polymorphic human leukocyte antigen (HLA) genetic loci. Our technology combines the construction of probe libraries on color-encoded microparticles (beads) with semiconductor chip processing to produce custom-designed high-density bead array chips in large quantities. Using this novel assay format, two modes of parallel molecular typing of the HLA complex were implemented, namely direct hybridization, illustrated here for class II HLA-DR, and a novel format of on-chip polymerase-mediated primer elongation, illustrated here for class I HLA-A, HLA-B, and HLA-DR using patient and reference cell-line DNA samples. Hybridization-mediated multiplexed analysis of polymorphism method was validated with 142 samples, resulting in 100% concordance with sequence-specific oligonucleotide typing results and a concomitant average of 40% less allele ambiguity. In addition, elongation and hybridization reactions were combined to identify multiple polymorphisms on the same phase of DNA for allele identification.

HLA Antigens↗