Amino acid 95 causes strong alteration of peptide position Pomega in HLA-B*41 variants

Association of Protective HLA-A With HLA-B∗27 Positive Ankylosing Spondylitis

Objectives

To further elucidate the role of the MHC in ankylosing spondylitis by typing 17 genes, searching for HLA-B^∗27 independent associations and assessing the impact of sex on this male biased disease.

Methods

High-confidence two-field resolution genotyping was performed on 310 cases and 2196 controls using an n-1 concordance method. Protein-coding variants were called from next-generation sequencing reads using up to four software programs and the consensus result recorded. Logistic regression tests were applied to the dataset as a whole, and also in stratified sets based on sex or HLA-B^∗27 status. The amino acids driving association were also examined.

Results

Twenty-five HLA protein-coding variants were significantly associated to disease in the population. Three novel protective associations were found in a HLA-B^∗27 positive population, HLA-A^∗24:02 (OR = 0.4, CI = 0.2–0.7), and HLA-A amino acids Leu95 and Gln156. We identified a key set of seven loci that were common to both sexes, and robust to change in sample size. Stratifying by sex uncovered three novel risk variants restricted to the female population (HLA-DQA1^∗04.01, -DQB1^∗04:02, -DRB1^∗08:01; OR = 2.4–3.1). We also uncovered a set of neutral variants in the female population, which in turn conferred strong effects in the male set, highlighting how population composition can lead to the masking of true associations.

Conclusion

Population stratification allowed for a nuanced investigation into the tightly linked MHC region, revealing novel HLA-B^∗27 signals as well as replicating previous HLA-B^∗27 dependent results. This dissection of signals may help to elucidate sex biased disease predisposition and clinical progression.

The Mechanistic Differences in HLA-Associated Carbamazepine Hypersensitivity

Drug hypersensitivity reactions that resemble acute immune reactions are linked to certain human leucocyte antigen (HLA) alleles. Severe and life-threatening Stevens Johnson Syndrome and Toxic Epidermal Necrolysis following treatment with the antiepileptic and psychotropic drug Carbamazepine are associated with HLA-B*15:02; whereas carriers of HLA-A*31:01 develop milder symptoms. It is not understood how these immunogenic differences emerge genotype-specific. For HLA-B*15:02 an altered peptide presentation has been described following exposure to the main metabolite of carbamazepine that is binding to certain amino acids in the F pocket of the HLA molecule. The difference in the molecular mechanism of these diseases has not been comprehensively analyzed, yet; and is addressed in this study. Soluble HLA-technology was utilized to examine peptide presentation of HLA-A*31:01 in presence and absence of carbamazepine and its main metabolite and to examine the mode of peptide loading. Proteome analysis of drug-treated and untreated cells was performed. Alterations in sA*31:01-presented peptides after treatment with carbamazepine revealed different half-life times of peptide-HLA- or peptide-drug-HLA complexes. Together with observed changes in the proteome elicited through carbamazepine or its metabolite these results illustrate the mechanistic differences in carbamazepine hypersensitivity for HLA-A*31:01 or B*15:02 patients and constitute the bridge between pharmacology and pharmacogenetics for personalized therapeutics.

Carbamazepine-Mediated Adverse Drug Reactions: CBZ-10,11-epoxide but Not Carbamazepine Induces the Alteration of Peptides Presented by HLA-B∗15:02

Among patients treated with the anticonvulsive and psychotropic drug carbamazepine (CBZ), approximately 10% develop severe and life-threatening adverse drug reactions. These immunological conditions are resolved upon withdrawal of the medicament, suggesting that the drug does not manifest in the body in long term. The HLA allele B∗15:02 has been described to be a genomic biomarker for CBZ-mediated immune reactions. It is not well understood if the immune reactions are triggered by the original drug or by its metabolite carbamazepine-10,11-epoxide (EPX) and how the interaction between the drug and the distinct HLA molecule occurs. Genetically engineered human B-lymphoblastoid cells expressing soluble HLA-B∗15:02 molecules were treated with the drug or its metabolite. Functional pHLA complexes were purified; peptides were eluted and sequenced. Applying mass spectrometric analysis, CBZ and EPX were monitored by analyzing the heavy chain and peptide fractions separately for the presence of the drug. This method enabled the detection of the drug in a biological situation post-pHLA assembly. Both drugs were bound to the HLA-B∗15:02 heavy chain; however, solely EPX altered the peptide-binding motif of B∗15:02-restricted peptides. This observation could be explained through structural insight; EPX binds to the peptide-binding region and alters the biochemical features of the F pocket and thus the peptide motif. Understanding the nature of immunogenic interactions between CBZ and EPX with the HLA immune complex will guide towards effective and safe medications.

Personalized adoptive immunotherapy for patients with EBV-associated tumors and complications: Evaluation of novel naturally processed and presented EBV-derived T-cell epitopes

Morbidity and mortality of immunocompromised patients are increased by primary infection with or reactivation of Epstein-Barr virus (EBV), possibly triggering EBV⁺ post-transplant lymphoproliferative disease (PTLD). Adoptive transfer of EBV-specific cytotoxic T cells (EBV-CTLs) promises a non-toxic immunotherapy to effectively prevent or treat these complications. To improve immunotherapy and immunomonitoring this study aimed at identifying and evaluating naturally processed and presented HLA-A*03:01-restricted EBV-CTL epitopes as immunodominant targets. More than 15000 peptides were sequenced from EBV-immortalized B cells transduced with soluble HLA-A*03:01, sorted using different epitope prediction tools and eleven candidates were preselected. T2 and Flex-T peptide-binding and dissociation assays confirmed the stability of peptide-MHC complexes. Their immunogenicity and clinical relevance were evaluated by assessing the frequencies and functionality of EBV-CTLs in healthy donors (n > 10) and EBV⁺ PTLD-patients (n = 5) by multimer staining, Eli- and FluoroSpot assays. All eleven peptides elicited EBV-CTL responses in the donors. Their clinical applicability was determined by small-scale T-cell enrichment using Cytokine Secretion Assay and immunophenotyping. Mixtures of these peptides when added to the EBV Consensus pool revealed enhanced stimulation and enrichment efficacy. These EBV-specific epitopes broadening the repertoire of known targets will improve manufacturing of clinically applicable EBV-CTLs and monitoring of EBV-specific T-cell responses in patients.

HLA-A*02 alleles are associated with tetanus antitoxin-induced exanthematous drug eruptions in Chinese patients

OBJECTIVE

Tetanus antitoxin (TAT) is an effective antitetanus medicine, but may sometimes cause adverse drug reactions such as rapid-onset anaphylactic shock and late-onset cutaneous adverse drug reactions, including exanthematous drug eruptions (EDE). Human leukocyte antigen (HLA) class I alleles are strongly associated with different types of cutaneous adverse drug reactions. This study aimed to assess whether there is an association between TAT-induced EDE and HLA-A, HLA-B, and HLA-C alleles in the Chinese Han population.

PATIENTS AND METHODS

We carried out an association study in 15 patients with TAT-induced EDE and two groups of general Han Chinese patients. Allele-level genotypes of the HLA-A, HLA-B, and HLA-C genes of each patient were determined using the PCR-sequence-specific oligonucleotides method.

RESULTS

The carrier frequency of HLA serotype A2 was significantly higher in the TAT-induced EDE patients than in the general Han Chinese study participants from the human major histocompatibility complex database [n=283, odds ratio (OR)=6.93; P=0.0061]. Particularly, the carrier frequency of three A2 alleles, including HLA-A*02:01, HLA-A*02:06, and HLA-A*02:07, is significantly higher than that of the control group (OR=14.40; P=2.4×10). Furthermore, HLA-B*39:01 was in complete linkage disequilibrium with HLA-A*02:06 in the case patients. Consequently, the distribution of the HLA-A*02:06/-B*39:01 haplotype was also significantly different in the cases and the controls (OR=105.00; P=0.0024).

CONCLUSION

The HLA-A*02:06/-B*39:01 haplotype is a potential genetic marker for the TAT-induced EDE. Furthermore, the HLA-A2 serotype, especially three alleles A*02:01, A*02:06, and A*02:07, was identified to be associated with the TAT-induced EDE in the Han Chinese population for the first time.

The diversity of the HLA-E-restricted peptide repertoire explains the immunological impact of the Arg107Gly mismatch

Human leukocyte antigen (HLA)-E molecules are potent inhibitors of NK cell-mediated killing. Low in polymorphisms, two alleles are widely expressed among diverse populations: HLA-E*01:01 and HLA-E*01:03. Both alleles are distinguished by one SNP resulting in the substitution Arg107Gly. Both alleles present a limited set of peptides derived from class I leader sequences physiologically; however, HLA-E*01:01 presents non-canonical peptides in the absence of HLA class I molecules. To further assess the functional differences between both alleles, we analyzed the peptide repertoire of HLA-E*01:03 by applying soluble HLA technology followed by mass-spectrometric peptide sequencing. HLA-E*01:03 restricted peptides showed a length of 9-17 amino acids and differed in their biophysical properties, no overlap in the peptide repertoire of both allelic variants could be observed; however, both alleles shared marginal peptides from the same proteomic content. Artificial APCs expressing empty HLA-E*01:01 or E*01:03 molecules were generated and stabilized using cognate HLA class I-derived peptide ligands to analyze the impact of residue 107 within the HLA-E heavy chain on the NKG2/CD94 receptor engagement. Differences in peptide stabilization could be translated to the density and half-life time of peptide-HLA-E molecules on the cell surface that subsequently impacted NK cell inhibition as verified by cytotoxicity assays. Taken together, these data illustrate functional differences of HLA-E allelic variants induced by a single amino acid. Furthermore, the function of HLA-E in pathophysiologic situations when the HLA processing machinery is interrupted seems to be more emphasized than previously described, implying a crucial role for HLA-E in tumor or viral immune episodes.

HLA-E: a novel player for histocompatibility

The classical class I human leukocyte antigens (HLA-A, -B, and -C) present allele-specific self- or pathogenic peptides originated by intracellular processing to CD8(+) immune effector cells. Even a single mismatch in the heavy chain (hc) of an HLA class I molecule can impact on the peptide binding profile. Since HLA class I molecules are highly polymorphic and most of their polymorphisms affect the peptide binding region (PBR), it becomes obvious that systematic HLA matching is crucial in determining the outcome of transplantation. The opposite holds true for the nonclassical HLA class I molecule HLA-E. HLA-E polymorphism is restricted to two functional versions and is thought to present a limited set of highly conserved peptides derived from class I leader sequences. However, HLA-E appears to be a ligand for the innate and adaptive immune system, where the immunological response to peptide-HLA-E complexes is dictated through the sequence of the bound peptide. Structural investigations clearly demonstrate how subtle amino acid differences impact the strength and response of the cognate CD94/NKG2 or T cell receptor.

Soluble HLA technology as a strategy to evaluate the impact of HLA mismatches

HLA class I incompatibilities still remain one of the main barriers for unrelated bone marrow transplantation (BMT); hence the molecular understanding of how to mismatch patients and donors and still have successful clinical outcomes will guide towards the future of unrelated BMT. One way to estimate the magnitude of polymorphisms within the PBR is to determine which peptides can be selected by individual HLA alleles and subsequently presented for recognition by T cells. The features (structure, length, and sequence) of different peptides each confer an individual pHLA landscape and thus directly shape the individual immune response. The elution and sequencing of peptides by mass spectrometric analysis enable determining the bona fide repertoire of presented peptides for a given allele. This is an effective and simple way to compare the functions of allelic variants and make a first assessment of their degree of permissivity. We describe the methodology used for peptide sequencing and the limitations of peptide prediction tools compared to experimental methods. We highlight the altered peptide features that are observed between allelic variants and the need to discover the altered peptide repertoire in situations of "artificial" graft versus host disease (GvHD) that occur in HLA-specific hypersensitive immune responses to drugs.

Peptide-binding motifs and characteristics for HLA -B*13:01 molecule

Trichloroethylene (TCE)-induced hypersensitivity dermatitis is one of the critical occupational diseases among workers in China. Our previous studies have identified a strong linkage between the disease and the HLA-B*13:01 allele. In this study, we searched for peptides bound to the HLA-B*13:01 molecule; 57 HLA-B*13:01-bound peptides in total were identified and 54 peptides were used to calculate frequency of amino acid residues to obtain binding motifs of HLA-B*13:01 molecule. The results showed P2, P3, and P9 were the primary binding anchor positions with the dominant anchor motifs of L, Q at P2, L at P9, D at P3. HLA-B*13:01-bound peptides were identified for the first time in our research, the results of which could contribute to the human leukocyte antigen (HLA)-binding peptides database.

HLA-B*13:01 and the dapsone hypersensitivity syndrome

BACKGROUND

Dapsone is used in the treatment of infections and inflammatory diseases. The dapsone hypersensitivity syndrome, which is associated with a reported mortality of 9.9%, develops in about 0.5 to 3.6% of persons treated with the drug. Currently, no tests are available to predict the risk of the dapsone hypersensitivity syndrome.

METHODS

We performed a genomewide association study involving 872 participants who had received dapsone as part of multidrug therapy for leprosy (39 participants with the dapsone hypersensitivity syndrome and 833 controls), using log-additive tests of single-nucleotide polymorphisms (SNPs) and imputed HLA molecules. For a replication analysis, we genotyped 24 SNPs in an additional 31 participants with the dapsone hypersensitivity syndrome and 1089 controls and performed next-generation sequencing for HLA-B and HLA-C typing at four-digit resolution in an independent series of 37 participants with the dapsone hypersensitivity syndrome and 201 controls.

RESULTS

Genomewide association analysis showed that SNP rs2844573, located between the HLA-B and MICA loci, was significantly associated with the dapsone hypersensitivity syndrome among patients with leprosy (odds ratio, 6.18; P=3.84×10(-13)). HLA-B*13:01 was confirmed to be a risk factor for the dapsone hypersensitivity syndrome (odds ratio, 20.53; P=6.84×10(-25)). The presence of HLA-B*13:01 had a sensitivity of 85.5% and a specificity of 85.7% as a predictor of the dapsone hypersensitivity syndrome, and its absence was associated with a reduction in risk by a factor of 7 (from 1.4% to 0.2%). HLA-B*13:01 is present in about 2 to 20% of Chinese persons, 1.5% of Japanese persons, 1 to 12% of Indians, and 2 to 4% of Southeast Asians but is largely absent in Europeans and Africans.

CONCLUSIONS

HLA-B*13:01 was associated with the development of the dapsone hypersensitivity syndrome among patients with leprosy. (Funded by the National Natural Science Foundation of China and others.).

Pocketcheck: updating the HLA class I peptide specificity roadmap

The structural determination of peptide:HLA (human leucocyte antigen) class I complexes by X-ray crystallography has provided valuable information for understanding how peptides bind to individual HLA class I molecules and how this may influence the immune response. We compared 101 crystal structures of 9-mer peptide:HLA class I complexes available in the protein data bank (PDB) by performing a contact analysis using the Contact Map Analysis webserver http://ligin.weizmann.ac.il/cma. An InterSystems Caché 'post-relational' database containing residue position, amino acid (AA) and buried surface that contact a particular peptide position was then created allowing data comparison for all the structures (Pocketcheck). The analysis illustrates that the HLA class I residues 24, 45, 63 and 67 show high contact frequencies to both the p1 and/or p2 position of bound peptides, indicating that they might influence the nature of a peptide anchor. To determine the influence of these residues we utilized soluble HLA technology and mass spectrometry to analyze peptides derived from HLA-B*44:06 since it differs from the previously described allele B*44:02 by seven AA exchanges located in the alpha 1 domain (residues 24, 32, 41, 45, 63, 67 and 80). HLA-B*44:06 features an anchor motif of P or A at p2 and Y or W at the C-terminal. Additionally B*44:06-derived peptides feature an auxiliary anchor motif at p1, comprising D or E. Our results illustrate that structural analysis can provide valuable information to understand allogenicity and provides a further step towards intelligent HLA mismatching.

Residue 81 confers a restricted C-terminal peptide binding motif in HLA-B*44:09

Knowledge about the magnitude of individual polymorphism is a critical part in understanding the complexity of comprehensive mismatching. HLA-B*44:09 differs from the highly frequent HLA-B*44:02 allele by amino acid exchanges at residues 77, 80, 81, 82 and 83. We aimed to identify the magnitude of these mismatches on the features of HLA-B*44:09 bound peptides since residues 77, 80 and 81 comprise part of the F pocket which determines sequence specificity at the pΩ position of the peptide. Using soluble HLA technology we determined >200 individual (nonduplicate) self-peptides from HLA-B*44:09 and compared their features with that of the published peptide features of HLA-B*44:02. Both alleles illustrate an anchor motif of E at p2. In contrast to the C-terminal peptide binding motif of B*44:02 (W, F, Y or L), B*44:09-derived peptides are restricted predominantly to L or F. The source of peptides for both alleles is identical (LCL 721.221 cells) allowing us to identify 23 shared peptides. The majority of these peptides however contained the restricted B*44:09 anchor motif of F or L at the pΩ position. Molecular modelling based on the B*44:02 structure highlights that the differences of the C-terminal peptide anchor between both alleles can be explained primarily by the B*44:02(81Ala) > B*44:09(81Leu) polymorphism which restricts the size of the amino acid that can be accommodated in the F pocket of B*44:09. These results highlight that every amino acid substitution has an impact of certain magnitude on the alleles function and demonstrate how surrounding residues orchestrate peptide specificity.

Position 45 influences the peptide binding motif of HLA-B*44:08

Position 45 represents a highly polymorphic residue within HLA class I alleles, which contacts the p2 position of bound peptides in 85% of the peptide-HLA structures analyzed, while the neighboring residues 41 and 46 are not involved in peptide binding. To investigate the influence of residue 45 at the functional level, we sequenced peptides eluted from recombinant HLA-B*44:08(41Ala/45Met/46Ala) molecules and compared their features with known peptides from B*44:02(41Thr/45Lys/46Glu). While HLA-B*44:02 has an anchor motif of E at the p2 anchor position, HLA-B*44:08 exhibits Q and L as anchor motif. The 45(Met/Lys) polymorphism contributes to the alteration in the peptide-binding motif and provides further evidence that mismatches at position 45 should be considered as nonpermissive in a transplantation setting.

Mismatches outside exons 2 and 3 do not alter the peptide motif of the allele group B*44:02P

Sequence variations outside exons 2 and 3 do not appear to affect the function of human leukocyte antigen (HLA) class I alleles. HLA-B*44:02:01:01 and -B*44:27 are considered functionally identical because they differ by a single amino acid substitution of Val > Ala at position 199, which is located in the α3 domain. To validate that HLA-B*44:02:01:01 and -B*44:27 represent functionally identical alleles that might reflect a permissive mismatch in hematopoetic stem cell transplantation (HSCT), we determined their peptide-binding features. B-lymphoblastic cells were lentivirally transduced with B*44:02 and B*44:27 constructs and soluble recombinant molecules were purified by affinity chromatography. Peptides were isolated and sequencing of single peptides was performed using liquid chromatography-electrospray ionization-tandem mass spectrometry (LTQ-Orbitrap) technology. We demonstrate that the peptide motif of B*44:02(199Val) and B*44:27(199Ala) is identical. Both variants feature E at P2 and Y, F, or W at PΩ in their ligands. Most of the identified peptides are 9 to 11 amino acids in length and approximately 20% of these ligands are shared between the alleles. Our results lead to the conclusion that B*44:02:01:01 and B*44:27 might have the same immune function, validating a theory that is now being used in deciding which donors to select in HSCT when there is no identical donor available.

The composition of the F pocket in HLA-A*74 generates C-terminal promiscuity among its bound peptides

In this study we sequenced the bound peptides from three alleles belonging to the HLA-A*74 group (HLA-A*74:04, A*74:06 and A*74:07) that are distinguished by four polymorphic residues within the peptide-binding region. Our data illustrates that A*74:04 exhibits preference for L, M or I at P2 and L, S or P at PΩ, while for A*74:07 the P2 anchor prefers L, P or I and the PΩ anchor S, P, L. In contrast A*74:06 features a P2 anchor motif of S or L, while a PΩ anchor could not be defined; however, a preference for polar residues S, T, Q or the charged residue R at the PΩ position could be detected.

Polymorphism between HLA-A*0301 and A*0302 located outside the pocket F alters the PΩ peptide motif

The human leukocyte antigen (HLA)-A*03 group has more than 90 known members and is one of the largest families of HLA class I alleles, with the most common variant being HLA-A*0301. In this study, we determined the peptide-binding motif of the highly frequent Sudanese allele A*0302 and compared it with the previously published peptide-binding motif of A*0301. The two alleles differ only at two distinct residues Glu152Val and Leu156Gln, which are predicted to be part of specificity pockets D, C and E and thus in contact with the peptide. Soluble recombinant A*0302 was expressed, affinity purified and the bound peptides were then eluted and analysed by mass spectrometry. The peptide-binding motif of A*0302 differs significantly from the previously published HLA-A*0301 and the Glu152Val/Leu156Gln mismatches appear to have a significant impact on the peptide-binding features of A*0302 and A*0301.

The impact of human leukocyte antigen (HLA) micropolymorphism on ligand specificity within the HLA-B*41 allotypic family

BACKGROUND

Polymorphic differences between human leukocyte antigen (HLA) molecules affect the specificity and conformation of their bound peptides and lead to differential selection of the T-cell repertoire. Mismatching during allogeneic transplantation can, therefore, lead to immunological reactions.

DESIGN AND METHODS

We investigated the structure-function relationships of six members of the HLA-B*41 allelic group that differ by six polymorphic amino acids, including positions 80, 95, 97 and 114 within the antigen-binding cleft. Peptide-binding motifs for B*41:01, *41:02, *41:03, *41:04, *41:05 and *41:06 were determined by sequencing self-peptides from recombinant B*41 molecules by electrospray ionization tandem mass spectrometry. The crystal structures of HLA-B*41:03 bound to a natural 16-mer self-ligand (AEMYGSVTEHPSPSPL) and HLA-B*41:04 bound to a natural 11-mer self-ligand (HEEAVSVDRVL) were solved.

RESULTS

Peptide analysis revealed that all B*41 alleles have an identical anchor motif at peptide position 2 (glutamic acid), but differ in their choice of C-terminal pΩ anchor (proline, valine, leucine). Additionally, B*41:04 displayed a greater preference for long peptides (>10 residues) when compared to the other B*41 allomorphs, while the longest peptide to be eluted from the allelic group (a 16mer) was obtained from B*41:03. The crystal structures of HLA-B*41:03 and HLA-B*41:04 revealed that both alleles interact in a highly conserved manner with the terminal regions of their respective ligands, while micropolymorphism-induced changes in the steric and electrostatic properties of the antigen-binding cleft account for differences in peptide repertoire and auxiliary anchoring.

CONCLUSIONS

Differences in peptide repertoire, and peptide length specificity reflect the significant functional evolution of these closely related allotypes and signal their importance in allogeneic transplantation, especially B*41:03 and B*41:04, which accommodate longer peptides, creating structurally distinct peptide-HLA complexes.

Essential differences in ligand presentation and T cell epitope recognition among HLA molecules of the HLA-B44 supertype

Human leukocyte antigens (HLA) have long been grouped into supertypes to facilitate peptide-based immunotherapy. Analysis of several hundreds of peptides presented by all nine antigens of the HLA-B44 supertype (HLA-B*18, B*37, B*40, B*41, B*44, B*45, B*47, B*49 and B*50) revealed unique peptide motifs for each of them. Taking all supertype members into consideration only 25 out of 670 natural ligands were found on more than one HLA molecule. Further direct comparisons by two mass spectrometric methods--isotope labeling as well as a label-free approach--consistently demonstrated only minute overlaps of below 3% between the ligandomes of different HLA antigens. In addition, T cell reactions of healthy donors against immunodominant HLA-B*44 and HLA-B*40 epitopes from EBV lacked promiscuous T-cell recognition within the HLA-B44 supertype. Taken together, these results challenge the common paradigm of broadly presented epitopes within this supertype.

HLA-B*1301 as a biomarker for genetic susceptibility to hypersensitivity dermatitis induced by trichloroethylene among workers in China

BACKGROUND

Trichloroethylene (TCE) is used extensively as an industrial solvent and has been recognized as one of the major environmental pollutants. To date, > 200 cases of TCE-induced hypersensitivity dermatitis among exposed workers have been reported worldwide, and TCE exposure has become one of the critical occupational health issues in Asia.

OBJECTIVES

The study aimed to identify genetic susceptible biomarkers associated with the TCE-induced hypersensitivity dermatitis in genes located in the human leukocyte antigen (HLA) region.

METHODS

From 1998 to 2006, 121 cases with TCE-induced hypersensitivity dermatitis and 142 tolerant controls were recruited into the population-based case-control study. We determined HLA alleles B, DRB1, DQA1, and DQB1, by sequence-based typing. p-Values were corrected for comparisons of multiple HLA alleles. In addition, we compared and analyzed the structure character of amino acid residues of HLA molecules found in participants.

RESULTS

We obtained complete genotyping data of 113 cases and 142 controls. The allele HLA-B*1301 was present in 83 (73.5%) of 113 patients compared with 13 (9.2%) of 142 tolerant workers (odds ratio = 27.5; 95% confidence interval, 13.5-55.7; corrected p = 1.48 x 10(-21)). In addition, the HLA-B*44 alleles were present in 6.2% (7/113) of patients, but were absent in TCE-tolerant workers. Residue 95 shared by HLA-B*1301 and HLA-B*44 molecules formed a different pocket F than other residues.

CONCLUSIONS

The allele HLA-B*1301 is strongly associated with TCE-induced hypersensitivity dermatitis among exposed workers and might be used as a biomarker to predict high risk individuals to TCE.