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PubMed1988

Hybrid genes between HLA-A2 and HLA-A3 constructed by in vivo recombination allow mapping of HLA-A2 and HLA-A3 polymorphic antigenic determinants.

HLA-A2 and -A3 genes have been modified in their third exon (second domain) by using in vivo recombination. In this method Escherichia coli are transfected with a plasmid which contains two highly homologous sequences (e.g., the third exons of HLA-A2 and -A3) and has been linearized by cleavage between these two sequences. Circularization takes place in the bacteria by homologous recombination leading to hybrid A2-A3 sequences. The analysis by DNA sequencing of a number of such recombinants shows that they indeed occur by homologous recombination (no insertions or deletions) and that the probability of crossing over decreases as the distance from the free end of DNA in the homologous region increases. No double recombinants were observed. These hybrid exons were reinserted into either HLA-A2 or HLA-A3 genes, thus generating a panel of functional hybrid genes containing one or several HLA-A2 specific substitutions in an HLA-A3 background or vice versa. These genes were expressed by transfection into murine P815-high transfection efficiency recipient cells. Serologic analysis leads to the conclusion that expression of polymorphic antigenic determinants specific for HLA-A2 (detected with M58, A2A28M1, and CR11.351 mAb) is linked to the presence of threonine residue (amino acid (AA) 142) and/or histidine residue (AA 145) and valine residue (AA 152). The expression of specific HLA-A3 polymorphic determinants (recognized by GAP-A3 mAb) is correlated with the existence of a asparagine residue (AA 127) and a aspartic residue (AA 161). But aspartic residue 161 contributes with glutamic acid residue 152 in the formation of the A3 epitope recognized by the anti-A3 mAb X1.23.2.

Antibodies, Monoclonal↗

PubMed1990

Structure and diversity of HLA-B27-specific T cell epitopes. Analysis with site-directed mutants mimicking HLA-B27 subtype polymorphism.

HLA-B27 subtype polymorphism is amenable to differential recognition by CTL. Site-directed mutagenesis was used to construct a series of HLA-B27 mutants reproducing most of the changes occurring in the natural subtypes. The reactivity of 21 anti-HLA-B27 CTL clones was examined with these mutants to address three issues concerning the alloreactive response against HLA-B27: 1) diversity of clonotypic specificities, 2) structural features of the epitopes recognized by these clones, and 3) role of individual positions in the differential recognition of HLA-B27 subtypes. Virtually all CTL clones displayed unique reaction patterns with the mutants, indicating a corresponding diversity of epitopes. However, these share some molecular features, such as certain amino acid residues and related locations. Individual mutations induced complex effects on multiple B27-specific CTL epitopes, revealing some of their very precise stereochemical constrains. An important feature of HLA-B27 subtype polymorphism is that every individual change was relevant, altering recognition by many CTL clones. Although the specific set affected by each mutation was partially different, the global number of clones affected by most changes was very similar. This suggests that the antigenic profile of any given subtype is not dominated by one particular change but is uniquely defined by its corresponding set of changes. An exception was the change at position 152, which totally abrogated recognition by all 20 anti-B*2705 CTL clones. This effect decisively influences the profound differences in T cell recognition between B*2705 and the two subtypes, B*2704 and B*2706, carrying this change. The results are compatible with the idea that HLA-B27 allorecognition may involve multiple peptides bound to the alloantigen on the cell surface.

Amino Acid Sequence↗

PubMed1986

HLA-DQ structural polymorphism in HLA-DR2 associated HLA-D clusters.

Three homozygous cell lines with different cellular HLA-D specificities associated with HLA-DR2 including Dw2, Dw12, DB9 displayed structural variation in the products of the DQ locus. Nonglycosylated precursor polypeptides of DQ molecules immunoprecipitated by two-dimensional polyacrylamide gel electrophoresis (2-D gel) revealed distinct differences in the patterns of DQ alpha and DQ beta chains.

Antibodies, Monoclonal↗

PubMed1986

HLA-DO polymorphism associated with resistance to type I diabetes detected with monoclonal antibodies, isoelectric point differences, and restriction fragment length polymorphism.

A new HLA-DQ-related genetic system with two alleles, 2B3 and TA10, defined serologically by MAbs and alloantisera, showed an almost perfect correlation with charge differences on DQ beta molecules, as well as with two polymorphic DNA fragments hybridizing with a DQ beta probe and various restriction enzymes on a panel of 14 DR4+ homozygous typing cells. It was therefore concluded that the serologically defined alleles 2B3 and TA10 are coded by the DQ beta gene and situated on the HLA-DQ beta chain. This 2B3/TA10 polymorphism is independent of HLA-D and segregates with HLA in families. The TA10 allele appears to be a new marker for resistance to type I diabetes, which is independent from the known resistance marker DR2, whereas no association was observed between this DQ beta polymorphism and rheumatoid arthritis.

Antibodies, Monoclonal↗

PubMed1989

Selective changes in expression of HLA class I polymorphic determinants in human solid tumors.

Analysis of surgical biopsies with monoclonal antibodies (mAbs) to framework determinants of major histocompatibility complex class I antigens has shown that malignant transformation is frequently associated with a marked loss of these cell surface molecules. The present study sought to determine whether more selective losses of major histocompatibility complex class I expression occur. Multiple specimens from 13 different types of primary and metastatic tumors were tested utilizing mAb BB7.2, which recognizes a polymorphic HLA-A2 epitope. In each case, expression of HLA-A,B,C molecules was determined by testing with mAb W6/32 directed to a framework HLA class I determinant. We have found that in HLA-A2-positive patients (identified by reactivity of their normal tissues with mAb BB7.2), HLA-A2 products are not detectable or are reduced in their expression in 70-80% of endometrial, colorectal, mammary, and renal tumors; in 40-60% of soft-tissue, skin, ovary, urinary bladder, prostate, and stomach tumors; and in 25-30% of melanomas and lung carcinomas tested. All tumors expressed the framework HLA-A,B,C determinant. The HLA-A2 epitope recognized by mAb BB7.2 is located in a portion of the HLA-A2 molecule postulated to react with the T-cell receptor. Immune surveillance to tumors is thought to depend on cytotoxic T cells, which require corecognition of polymorphic HLA class I epitopes, and on natural killer cells, which are, on the contrary, activated by the absence of HLA class I antigens. The selective loss of an HLA class I polymorphic epitope shown in this study may explain the mechanism by which tumor cells escape both T-cell recognition and natural killer cell surveillance.

Antibodies, Monoclonal↗

PubMed1992

Autoimmunity in vitiligo: relationship with HLA, Gm and Km polymorphisms.

Eighty-six patients affected by vitiligo were investigated for Gm, and Km polymorphisms, HLA markers and the presence of organ and non organ-specific autoantibodies. Vitiligo patients had an increased frequency of autoantibodies (71%), in particular anti-parietal cells (26.6%), antithyroglobulin (24.4%) and antithyroid microsomal antibodies (43%). One patient was also affected by Hashimoto's thyroiditis, 4 by Graves' disease and two others by nontoxic, multinodular goiter. No correlation was found between chronologic age and sex and the presence of autoantibodies, while an increased frequency of organ-specific autoantibodies was found with longer duration of vitiligo. HLA-A3 and Gm (3; 23; 5, 10, 11, 13, 14) phenotype frequencies were significantly increased in patients without autoantibodies (P less than 0.05). Patients negative for these two phenotypes were significantly more prone to develop autoantibodies than those positive (P = 0.0032). C4AQO allele showed a significantly decreased frequency in the whole group of patients when compared to the controls (P less than 0.05).

Adolescent↗

PubMed1999

HLA-DRB1 polymorphisms and autoimmune responses to desmogleins in Japanese patients with pemphigus.

Pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are caused by autoantibodies against keratinocyte adhesion molecules desmoglein 3 (Dsg3) and desmoglein 1 (Dsg1), respectively. To determine possible major histocompatibility complex (MHC) class II associations with autoantibody responses to desmogleins, haplotype and allele distributions, along with molecular polymorphisms of HLA-DR and -DQ genes were analyzed based on the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) results in 85 Japanese patients with pemphigus. Each of 55 PV patients carried at least one allele of HLA-DRB1*04 and DRB1*14 subtypes, with significant increases of HLA-DRB1*0406/DQA1*0301/DQB1*0302, DRB1*14/DQA1*0104/DQB1*05 and DRB1*1406/DQA1*0503/ DQB1*0301 haplotypes compared to normal controls. The HLA-DRB1*04 and DRB*14 alleles carried by PV patients shared hydrophobic amino acid residues Phe26, Leu67 and Val86, as well as hydrophilic amino acid residues at positions 70 and 71 on the DRB1 beta chain. HLA-DR/DQ distributions did not differ among PV patients according to the presence or absence of anti-Dsg1 co-existing with anti-Dsg3. Thirty PF patients, all producing autoantibodies only to Dsg1, showed more diverse HLA-DR/DQ distributions, sharing hydrophobic amino acid residues at positions 26 and 67, as well as hydrophilic amino acid residues at positions 70 and 71, of the DRB1 chain. These findings suggest that autoantibody responses to desmogleins might be regulated by amino acid residues at positions 26, 67, 70, 71 and 86 at peptide binding sites of HLA-DRB1 molecules, and that autoimmune responses to Dsg3 might be more strictly regulated by specific amino acid residues at these positions on the HLA-DRB1 chain than responses to Dsg1.

Alleles↗

PubMed1998

HLA-G polymorphisms and allele frequencies in Caucasians.

HLA-G, a nonclassical class I MHC molecule, is uniquely expressed on extravillous cytotrophoblasts of the maternal-fetal interface and is suggested to be essential for establishment of maternal-fetal immune tolerance. Although the level of polymorphism in HLA-G has originally been considered low, number, nature and site of polymorphisms seem to vary between different ethnic populations. We investigated HLA-G polymorphisms in a population of German and Croatian origin by SSCP-analysis and direct sequencing as well as RFLP analysis for presence of the 1597delC mutation. HLA-A alleles associated with the different HLA-G alleles were determined by SSP PCR-typing. In Caucasians, HLA-G exhibits a low degree of polymorphism on the amino-acid level and only slightly higher variability on the nucleotide level. In 264 independent chromosomes, 4 HLA-G alleles on the level of amino acid polymorphisms and an additional 6 variations of nucleotide sequences could be identified. The null-allele G*0105N was present at an allele frequency of 2.3%, which is higher than initially suggested for Caucasians but lower than in Hispanics and African-Americans. Furthermore, some HLA-G alleles exhibit strong linkage disequilibrium with HLA-A.

Adult↗

PubMed2000

Polymorphisms of HLA DQB1 CAR1/CAR2 and TNFalpha IR2/IR4 microsatellite markers in patients affected with Graves disease.

Graves disease is an autoimmune thyroid disorder in which HLA class I and II confer susceptibility in different ethnic groups. An allele-specific polymerase chain reaction was used to characterize the variation of the HLA-DQB1 CAR1/CAR2 and TNFalpha markers located on chromosome 6 in 85 unrelated Tunisian patients affected with Graves disease and 148 healthy control subjects. In contrast to the results regarding TNFalpha alleles showing no difference between patients and controls (P = 0.904), the analysis of the HLA-DQB1 CAR1/CAR2 polymorphism showed a significant difference in its alleles (P < 0.0001). Nevertheless, no allele exhibited a predispositional effect on GD pathogenesis.

Alleles↗

PubMed1993

[HLA-DRB1 and HLA-DQB1 polymorphism in Algerians from Algiers].

The polymorphism of HLA-DRB1 and HLA-DQB1 genes in 100 unrelated Algerians from Alger was investigated using PCR amplification and oligonucleotide typing. Compared to western Europeans, this population shows a higher haplotypic frequency of HLA DRB1*03-DQB1*0201 (21.5%) and a lower haplotypic frequency of DRB1*0101-DQB1*0501 (2%). Two unexpected haplotypes are observed: DRB1*07-DQB1*0301 and DRB1*0406-DQB1*0402. DRB1*0402 is the most common subtype in the DRB1*04 group. Furthermore, we detected a rare DQB1*0305 allele, only found in a Sardinian subject until today.

Algeria↗

PubMed1986

Molecular analysis of a functional subtype of HLA-B27. A possible evolutionary pathway for HLA-B27 polymorphism.

The structure of a new HLA-B27 subtype antigen B27.4(B27D), distinguishable from the HLA-B27.1, B27.2, and B27.3 subtypes by cytolytic T lymphocytes and isoelectric focusing, has been established by comparative peptide mapping and sequence analysis. HLA-B27.4 differs from the main B27.1 subtype in the same two changes of aspartate-77 to serine-77 and valine-152 to glutamate-152, which distinguish the B27.1 and B27.3 subtypes. In addition, there are two other amino acid changes of histidine-114 to aspartate-114 and of aspartate-116 to tyrosine-116, which are unique to B27.4. The close structural relationship between B27.3 and B27.4 explains the similarity of these two subtypes in terms of T cell recognition. The presence of the two single amino acid differences between B27.3 and B27.4 within a span of three residues in the linear sequence provides a new example, suggesting that gene conversion-like mechanisms play a major role in the diversification of HLA-B27. A comparison of the structure of HLA-B27.4 with those of B27.1, B27.2, and B27.3 in the context of their ethnic distribution suggests that the diversification of the HLA-B27 antigens is an ongoing process that has continued after the separation of the major ethnic groups. A tentative evolutionary model for HLA-B27 polymorphism is proposed.

Amino Acid Sequence↗

PubMed1992

Polymorphisms of HLA class III genes in allergic contact dermatitis.

HLA class III polymorphisms (BF, C4A, C4B) were studied in 55 patients of different age and sex suffering from allergic contact dermatitis, with sensitization to different substances. In the overall group of patients no significant correlation between the disease and HLA markers was found. BF F allele was present in 34% and BS S in 64% of patients suffering from allergic contact dermatitis to nickel only versus 16.45% (relative risk, RR = 2.61) and 80.76% (RR = 0.42), respectively, of the control population. The BF FB subtype frequency was 23.91% versus 7.57% in the control samples (RR = 3.88). We thus hypothesize that this polymorphic serum protein might be involved in the pathogenesis of allergic contact dermatitis to nickel.

Adolescent↗

PubMed1994

HLA-DPB1 polymorphisms in patients with hyperthyroid Graves' disease and early onset myasthenia gravis.

Using the technique of in vitro enzymatic DNA amplification and dot blot hybridization with sequence-specific oligonucleotide (SSO) probes, a study of genetic polymorphism of HLA-DPB1 was performed in 83 unrelated patients with Graves' disease (GD), 48 patients with early onset myasthenia gravis (EOMG) and 100 normal British caucasoid subjects who were also tissue typed for HLA-A, B and DR antigens. HLA-DPB1*0401 was the commonest allele in both patient and control groups with gene frequencies of 0.380, 0.333 and 0.445 for GD, EOMG and controls, respectively. No significant independent association was found with any HLA-DPB1 allele. As expected, HLA-DR17 is significantly associated with Graves' disease (pc < 8 x 10(-3), RR = 2.9), while both HLA-B8 and DR17 are significantly associated with EOMG (pc < 2 x 10(-7), RR = 10.3 and pc < 0.02, RR = 3.4, respectively)] HLA-DR2 is also significantly increased in EOMG patients who were negative for HLA-DR17 (pc < 0.02, RR = 6.4). In addition, the co-occurrence of HLA-B8 with DPB1*0402 was significantly commoner in patients with GD (p < 0.021, RR = 6.2) and EOMG (p < 0.0007, RR = 10.8) than in controls, although the HLA-DPB1*0402 by itself showed no significant increase.

Adult↗

PubMed1998

HLA-G polymorphisms: ethnic differences and implications for potential molecule function.

PROBLEM: Human leukocyte antigen (HLA)-G is uniquely expressed on extravillous cytotrophoblasts of the placenta and is postulated to be a mediator of maternal immune tolerance. Although it was originally considered to be nonpolymorphic, variations of the HLA-G DNA sequence have been reported, and a limited number of HLA-G alleles been defined. METHOD OF STUDY: The HLA-G wild-type sequence was compared with HLA-A2 with regard to the conservation of functionally essential parts of classical HLA-I molecules. HLA-G polymorphisms were analyzed under the aspect of ethnic differences, site, and consequences for postulated molecule functions. RESULTS: HLA-G exhibits a high degree of conservation relative to HLA-A2 in functionally relevant sites of HLA-class I molecules. However, polymorphic sites in HLA-G and classical HLA loci are not congruent. CONCLUSION: The type and localization of HLA-G polymorphisms suggest that different parts of HLA-G molecule underlie different selective constraints.

Ethnicity↗

PubMed1994

HLA-DPB1 polymorphisms on the MHC-extended haplotypes of families of patients with Graves' disease: two distinct HLA-DR17 haplotypes.

HLA-DPB1 polymorphisms were investigated in 217 members of 21 multiplex families of patients with Graves' disease, who had previously been haplotyped, using in vitro enzymatic DNA amplification and hybridization with sequence-specific oligonucleotide probes. Using the strategy of group-specific amplification, we were able to assign 19 DPB1 alleles with the use of 13 sequence specific oligonucleotide probes. No recombination was found between HLA-DPB1 and the HLA-DR/DQ complex in 243 informative meioses. HLA-DPB1*0401 was found to be the most common allele followed by DPB1*0101, *0201 and 0402 with allele frequencies of 0.4214, 0.1132, 0.1069 and 0.1006, respectively. Besides the strong linkage disequilibrium between HLA-DPB1*0101 allele and the HLA-B8, DR17/DQ2 haplotype; HLA-DPB1*0202 and *1101 alleles were also found to be significantly associated with HLA-B18 and DR7 with Pc < 0.001 and Pc < 0.009, respectively. HLA-DR17/DQ2 was found to be more commonly associated with HLA-DPB1*0101 on the Affected haplotypes (from family members affected with Graves' disease) while associated with DPB1*0401 on the Ab + ve haplotypes (deduced from thyroid autoantibody positive unaffected members). The differences in the frequency of this preferential association on the Affected and Ab + ve haplotypes was statistically significant (ch 2 = 10.18, df = 2, P < 0.007). Though it is rater unlikely that the HLA-DPBI polymorphism by itself could contribute a direct role towards the genetic susceptibility for the development of autoimmune thyroid disease, it could serve as a marker in identifying family members with the HLA-DR17/DQ2 haplotype who are more likely to develop Grave's disease or thyroid autoantibodies.

Graves Disease↗

PubMed1992

Production and characterization of murine monoclonal antibodies recognizing HLA-DQ polymorphisms obtained by immunizing mice with transfected L cells.

Two polymorphic anti-HLA-DQB1 mAbs, TM 902 and TM 903, have been produced by immunizing F1 mice (Balb/C x C3H) with HLA-DQ-transfected mouse L cells. Cytotoxic analysis on a panel of HLA-typed cell lines has shown that TM 902 reacts with all the DQB1* alleles except DQB1*0501, *0502, and *0503, and DQB1*0601, *0602, *0603, and *0604, whereas TM 903 reacts with the DQB1*0501, *0502, and *0503, DQB1*0601, *0602, *0603, and *0604, and DQB1*0401 and *0402 alleles. The same reactivity pattern has been confirmed by cytofluorimetric analysis. Indirect immunofluorescence with various class-II-transfected cell lines showed no binding of both mAbs to the DR or DP products, suggesting their reactivity to the DQ products. The use of transfectants expressing HLA-DR/DQ heterodimers demonstrates that TM902 and TM903 mAbs are both specific for the DQ-beta chain. Comparison of the amino acid sequences of the DQ-beta chain suggests the involvement of residues 84-90 (QLELRTT) in the formation of TM902 epitope and of residues 54-55 (GR) in the formation of TM903 epitope.

Alleles↗

PubMed1996

Frequencies of HLA-A24 and HLA-DR4-DQ8 are increased and that of HLA-B blank is decreased in chronic toxic oil syndrome.

The cause of toxic oil syndrome (TOS) has not yet been definitively determined, but some genetic susceptibility factors (certain HLA antigens and female sex) have been identified in 236 patients. Similarities with genetic factors for scleroderma and hydralazine-induced lupus (i.e. in TOS female sex and HLA-A24, Pcorrected = 0.00001 and DR4, Pcorrected = 0.04, respectively) may provide a clue to the responsible xenobiotic and its pathogenesis, and may also help in understanding the basis of the related eosinophilia-myalgia syndrome associated with tryptophan ingestion. In this paper it is also established that a human class I antigen (HLA-A24) and, independently, an HLA class II haplotype (DR4-DQ8, Pcorrected = 0.04) and arginine 52 in the alpha-DQ chains (Pcorrected = 0.03) are associated with TOS susceptibility, similarly to insulin-dependent diabetes. This further supports the classification of TOS as an autoimmune disease. Also, the increased frequency of a particular set of low-frequency HLA class I antigens in chronic TOS patients (i.e. B27, B37, B38 and B49) and the probable decrease in the frequency of HLA-B homozygotes in surviving patients (Pcorrected = 0.008) may provide an objective model to explain the maintenance of the HLA polymorphism: less frequent HLA alleles may be more advantageous in the event of unexpected human contact with unusual xenobiotics (not only microbes); however, other mechanisms working together to preserve and generate HLA polymorphism may coexist.

Fatty Acids, Monounsaturated↗

PubMed2003

[HLA gene polymorphism and forensic medicine].

The gene complex of Human Leukocyte Antigen (HLA) is located of chromosome 6p21, which is the most complicated dominant polymorphic genetic system. The HLA system has 108 genotypes. It is the best human genetic marker. It has been applied to forensic paternity test and individual identification. This article discusses the research development of HLA polymorphism and its application in forensic medicine.

Forensic Medicine↗