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BackgroundHuman Papillomavirus type 18 (HPV18) is a high-risk HPV that is commonly associated with cervical cancer. HPV18 oncogenes E6 and E7 are associated with the malignant transformation of cells, thus the identification of human leukocyte antigen (HLA)-restricted E6/E7 peptide-specific CD8 + T cell epitopes and the creation of a HPV18 E6/E7 expressing cervicovaginal tumor in HLA-A2 transgenic mice will be significant for vaccine development.MethodsIn the below study, we characterized various human HLA class I-restricted HPV18 E6 and E7-specific CD8 + T cells mediated immune responses in HLA class I transgenic mice using DNA vaccines encoding HPV18E6 and HPV18E7. We then confirmed HLA-restricted E6/E7 specific CD8 + T cell epitopes using splenocytes from vaccinated mice stimulated with HPV18E6/E7 peptides. Furthermore, we used oncogenic DNA plasmids encoding HPV18E7E6(delD70), luciferase, cMyc, and AKT to create a spontaneous cervicovaginal carcinoma model in HLA-A2 transgenic mice.ResultsTherapeutic HPV18 E7 DNA vaccination did not elicit any significant CD8 + T cell response in HLA-A1, HLA-24, HLA-B7, HLA-B44 transgenic or wild type C57BL/6 mice, but it did generate a strong HLA-A2 and HLA-A11 restricted HPV18E7-specific CD8 + T cell immune response. We found that a single deletion of aspartic acid (D) at location 70 in HPV18E6 DNA abolishes the presentation of HPV18 E6 peptide (aa67-75) by murine MHC class I. We found that the DNA vaccine with this mutant HPV18 E6 generated E6-specific CD8 + T cells in HLA-A2. HLA-A11, HLA-A24 and HLA-b40 transgenic mice. Of note, HLA-A2 restricted, HPV18 E7 peptide (aa7-15)- and HPV18 E6 peptide (aa97-105)-specific epitopes are endogenously processed by HPV18 positive Hela-AAD (HLA-A*0201/Dd) cells. Finally, we found that injection of DNA plasmids encoding HPV18E7E6(delD70), AKT, cMyc, and SB100 can result in the development of adenosquamous carcinoma in the cervicovaginal tract of HLA-A2 transgenic mice.ConclusionsWe characterized various human HLA class I-restricted HPV18 E6/E7 peptide specific CD8 + T cell epitopes in human HLA class I transgenic mice. We demonstrated that HPV18 positive Hela cells expressing chimeric HLA-A2 (AAD) do present both HLA-A2-restricted HPV18 E7 (aa7-15)- and HPV18 E6 (aa97-105)-specific CD8 + T cell epitopes. A mutant HPV18E6 that had a single deletion at location 70 obliterates the E6 presentation by murine MHC class I and remains oncogenic. The identification of these human MHC restricted HPV antigen specific epitopes as well as the HPV18E6/E7 expressing adenosquamous cell carcinoma model may have significant future translational potential.

Human leukocyte antigen (HLA)-B has been recognized as a major determinant of discrepancies in disease outcomes, and recent evidence indicates a role in immune checkpoint blockade (ICB) efficacy. The B44 supertype, which features an electropositive binding pocket that preferentially displays peptides with negatively charged amino acid anchors, is associated with improved survival in ICB-treated melanoma. Yet this effect was not seen in ICB-treated non-small-cell lung cancer (NSCLC). Here we show that mutations leading to glutamic acid substitutions occur more often in melanoma than NSCLC based on mutational landscape. We additionally show stratifying B44 based on the presence of somatic mutations that lead to negatively charged glutamic acid anchors identifies patients with NSCLC with an ICB benefit similar to that seen in melanoma. We anticipate these findings could improve assessment of HLA-related outcomes and prediction of ICB benefit in those with B44, representing approximately half of the world’s population. Garon and colleagues demonstrate that the association of HLA supertype B44 with response to immune checkpoint blockade in melanoma but not NSCLC is related to differential mutational features that influence HLA binding of neoepitopes.

The spread of COVID-19 is showing huge, unexplained, differences between northern and southern Italy. We hypothesized that the regional prevalence of specific class I human leukocyte antigen (HLA) alleles, which shape the anti-viral immune response, might partly underlie these differences. Through an ecological approach, we analyzed whether a set of HLA alleles (A, B, C), known to be involved in the immune response against infections, correlates with COVID-19 incidence. COVID-19 data were provided by the National Civil Protection Department, whereas HLA allele prevalence was retrieved through the Italian Bone-Marrow Donors Registry. Among all the alleles, HLA-A*25, B*08, B*44, B*15:01, B*51, C*01, and C*03 showed a positive log-linear correlation with COVID-19 incidence rate fixed on 9 April 2020 in proximity of the national outbreak peak (Pearson’s coefficients between 0.50 and 0.70, p-value < 0.0001), whereas HLA-B*14, B*18, and B*49 showed an inverse log-linear correlation (Pearson’s coefficients between −0.47 and −0.59, p-value < 0.0001). When alleles were examined simultaneously using a multiple regression model to control for confounding factors, HLA-B*44 and C*01 were still positively and independently associated with COVID-19: a growth rate of 16% (95%CI: 0.1–35%) per 1% point increase in B*44 prevalence; and of 19% (95%CI: 1–41%) per 1% point increase in C*01 prevalence. Our epidemiologic analysis, despite the limits of the ecological approach, is strongly suggestive of a permissive role of HLA-C*01 and B*44 towards SARS-CoV-2 infection, which warrants further investigation in case-control studies. This study opens a new potential avenue for the identification of sub-populations at risk, which could provide Health Services with a tool to define more targeted clinical management strategies and priorities in vaccination campaigns.

Background Major histocompatibility complex class I chain–related (MIC) A and B (MICA and MICB) are polymorphic stress molecules recognized by natural killer cells. This study was performed to analyze MIC gene profiles in hospitalized Thai children with acute dengue illness. Methods MIC allele profiles were determined in a discovery cohort of patients with dengue fever or dengue hemorrhagic fever (DHF) (n = 166) and controls (n = 149). A replication cohort of patients with dengue (n = 222) was used to confirm specific MICB associations with disease. Results MICA*045 and MICB*004 associated with susceptibility to DHF in secondary dengue virus (DENV) infections (odds ratio [OR], 3.22; [95% confidence interval (CI), 1.18–8.84] and 1.99 [1.07–2.13], respectively), and MICB*002 with protection from DHF in secondary DENV infections (OR, 0.41; 95% CI, .21–.68). The protective effect of MICB*002 against secondary DHF was confirmed in the replication cohort (OR, 0.43; 95% CI, .22–.82) and was stronger when MICB*002 is present in individuals also carrying HLA-B*18, B*40, and B*44 alleles which form the B44 supertype of functionally related alleles (0.29, 95% CI, .14–.60). Conclusions Given that MICB*002 is a low expresser of soluble proteins, these data indicate that surface expression of MICB*002 with B44 supertype alleles on DENV-infected cells confer a protective advantage in controlling DENV infection using natural killer cells.

Major Histocompatibility Complex (MHC) is a cell surface glycoprotein that binds to foreign antigens and presents them to T lymphocyte cells on the surface of Antigen Presenting Cells (APCs) for appropriate immune recognition. Recently, studies focusing on peptide-based vaccine design have allowed a better understanding of peptide immunogenicity mechanisms, which is defined as the ability of a peptide to stimulate CTL-mediated immune response. Peptide immunogenicity is also known to be related to the stability of peptide-loaded MHC (pMHC) complex. In this study, ENCoM server was used for structure-based estimation of the impact of single point mutations on pMHC complex stabilities. For this purpose, two human MHC molecules from the HLA-B*27 group (HLA-B*27:05 and HLA-B*27:09) in complex with four different peptides (GRFAAAIAK, RRKWRRWHL, RRRWRRLTV and IRAAPPPLF) and three HLA-B*44 molecules (HLA-B*44:02, HLA-B*44:03 and HLA-B*44:05) in complex with two different peptides (EEYLQAFTY and EEYLKAWTF) were analyzed. We found that the stability of pMHC complexes is dependent on both peptide sequence and MHC allele. Furthermore, we demonstrate that allele-specific peptide-binding preferences can be accurately revealed using structure-based computational methods predicting the effect of mutations on protein stability.

Allele-level HLA compatibility in cord blood transplantation has been associated with better transplant outcomes and is recommended as a selection criterion. It is also a crucial aspect for other therapeutic applications involving cord blood-derived cells. Determination of high-resolution HLA frequencies is an important step towards improving the quality of cord blood banks. We analyzed HLA-A, -B, -C, -DRB1, and -DQB1 allele frequencies in 5458 high-quality cord blood units from the Barcelona Cord Blood Bank and identified 275 class I and 121 class II HLA alleles. A*02:01, B*44:03, C*07:01, DRB1*07:01 and DQB1*03:01 were the most frequent alleles at each locus. We detected 26 novel alleles and were able to determine the presence or absence of some null alleles, including C*04:09N, in a large number of units. We also analyzed maternal HLA typing information for 1877 units to determine real haplotype frequencies and linkage disequilibrium. A*29:02-B*44:03-C*16:01-DRB1*07:01-DQB1*02:02 was the most frequent HLA haplotype and the DRB1-DQB1 gene pair contained the two-locus haplotypes with the strongest linkage disequilibrium values. Four of the 11 unique haplotypes identified in the HLA-homozygous cord blood units were the top-ranking haplotypes identified and were present in 18% of the cohort. This is the first study to report on HLA allele and haplotype frequencies for umbilical cord blood units from the Barcelona Cord Blood Bank and the largest study to date involving two fields of HLA resolution typing of Spanish registry data.

Objective:In a previous pilot monocentric study, we investigated the relation between human leukocyte antigen (HLA) genotype and multiple sclerosis (MS) disease progression over 2 years. HLA-A*02 allele was correlated with better outcomes, whereas HLA-B*07 and HLA-B*44 were correlated with worse outcomes. The objective of this extension study was to further investigate the possible association of HLA genotype with disease status and progression in MS as measured by sensitive and complex clinical and imaging parameters.Methods:Hundred and forty-six MS patients underwent HLA typing. Over a 4-year period of follow-up, we performed three clinical and magnetic resonance imaging (MRI) assessments per patient, which respectively included Expanded Disability Status Scale, Multiple Sclerosis Severity Scale, Timed-25-Foot-Walk, 9-Hole Peg Test, Symbol Digit Modalities Test, Brief Visual Memory Test, California Verbal Learning Test-II, and whole-brain atrophy, fluid-attenuated inversion recovery (FLAIR) lesion volume change and number of new FLAIR lesions using icobrain. We then compared the clinical and MRI outcomes between predefined HLA patient groups.Results:Results of this larger study with a longer follow-up are in line with what we have previously shown. HLA-A*02 allele is associated with potentially better MS outcomes, whereas HLA-B*07, HLA-B*44, HLA-B*08, and HLA-DQB1*06 with a potential negative effect. Results for HLA-DRB1*15 are inconclusive.Conclusion:In the era of MS treatment abundance, HLA genotype might serve as an early biomarker for MS outcomes to inform individualized treatment decisions.

Background Human leukocyte antigen (HLA) molecules play a key role in the cellular immune system. They may be determinants of mother-to-child transmission which is the driving force in pediatric HIV infection. We intended to look at the impact of the distribution of these polymorphic HLA genes in the mother-to-child transmission (MTCT) of HIV in Cameroon. Methods A total of 156 mother-baby pairs were enrolled in three hospitals of Yaounde, capital of Cameroon. After the extraction of the DNA from blood samples using the Qiagen Kit as per manufacturer’ instructions, the polymorphism of the HLA class 1 ABC was determined using the PCR- sequence specific primers assay. Results The distribution of HLA class 1 revealed that none of the allele studied was associated with transmitters or non-transmitters, so was not implicated in transmission. The regression analysis showed that HLA A*32 [OR 0.062 (CI; 0.0075 to 0.51)] is associated with HIV acquisition while HLA B*44 [OR 0.47 (CI; 0.21 to 1.14)] and HLA B*53 [OR; 0.14 (CI; 0.018 to 1.22)] were implicated in reducing the acquisition of HIV by infants. The homozygosity of locus C [OR 6.99 (CI; 1.81 to 26.88), p = 0.0027] was found as a risk factor for the acquisition, while the A*32-B*44 haplotype [OR 10.1 (CI 1.17 to 87.87), p = 0.03] was a risk factor for the transmission. Conclusion This study has found that HLA A*32, B*44 and B*53 have an impact in MTCT outcomes. The homozygosity of locus C and the A*32-B*44 haplotype were risk factors for acquisition and transmission respectively. Electronic supplementary material The online version of this article (10.1186/s12887-019-1620-6) contains supplementary material, which is available to authorized users.

Lack of disease during chronic human cytomegalovirus (CMV) infection depends on the maintenance of a high-frequency CMV-specific T cell response. The composition of the T cell receptor (TCR) repertoire underlying this response remains poorly characterised, especially within African populations in which CMV is endemic from infancy. Here we focus on the immunodominant CD8+ T cell response to the immediate-early 2 (IE-2)-derived epitope NEGVKAAW (NW8) restricted by HLA-B*44:03, a highly prevalent response in African populations, which in some subjects represents >10% of the circulating CD8+ T cells. Using pMHC multimer staining and sorting of NW8-specific T cells, the TCR repertoire raised against NW8 was characterised here using high-throughput sequencing in 20 HLA-B*44:03 subjects. We found that the CD8+ T cell repertoire raised in response to NW8 was highly skewed and featured preferential use of a restricted set of V and J gene segments. Furthermore, as often seen in immunity against ancient viruses like CMV and Epstein-Barr virus (EBV), the response was strongly dominated by identical TCR sequences shared by multiple individuals, or "public" TCRs. Finally, we describe a pair "superdominant" TCR clonotypes, which were germline or nearly germline-encoded and produced at remarkably high frequencies in certain individuals, with a single CMV-specific clonotype representing up to 17% of all CD8+ T cells. Given the magnitude of the NW8 response, we propose that this major skewing of CMV-specific immunity leads to massive perturbations in the overall TCR repertoire in HLA-B*44:03 individuals.

HLA-B*44:03:01:19 differs from HLA-B*44:03:01:01 by a single nucleotide substitution (T➔C) at position 3856.

MHC class I molecules present antigenic peptides to cytotoxic T-cells at the cell surface. Peptide loading of class I molecules in the endoplasmatic reticulum can involve interaction with the tapasin chaperone protein. The human class I allotype HLA-B*44:02 with an Asp at position 116 at the floor of the F pocket (which binds the peptide C-terminal residues) depends on tapasin for efficient peptide loading. However, HLA-B*44:05 (identical to B*44:02 except for tyrosine 116) can efficiently load peptides in the absence of tapasin. Both allotypes adopt very similar structures in the presence of the same peptide. Molecular dynamics simulations indicate a significantly higher conformational flexibility of the F pocket in the absence of a peptide for B*44:02 compared to B*44:05. Free energy simulations to open the F pocket indicate a molecular side chain switch mechanism that underlies the global opening motion. This side chain switch involves the rearrangement of salt bridges and hydrogen bonding of the basic arginine 97 with three acidic aspartate residues 114, 116 and 156 near the F pocket. A replica exchange simulation to specifically accelerate side chain motions demonstrates that the same side chain rearrangements induce global opening motions of the F pocket. In case of B*44:05 the free energy barrier for F pocket opening was significantly higher compared to B*44:02 and no associated side chain rearrangement was observed. Such coupling of local side chain rearrangements with global conformational changes might be the basis for allosteric changes in other class I allotypes as well as for allosteric changes in other proteins.

IFNL3 is the strongest predictor of spontaneous resolution (SR) of hepatitis C virus (HCV), however, consideration of IFNL3 genotype alone is of limited clinical value for the prediction of SR or chronic HCV infection. The objective of this study was to analyze the impact of HLA-B, HLA-C and KIRs on SR, as well as their additive effects on the predictive value of the IFNL3 genotype. We conducted a retrospective study of HIV patients that included both SR and chronic HCV patients. In our study, 61.6% of patients with IFNL3 CC achieved SR, and 81.5% with non-CC genotypes did not achieve SR. HLA-B*44, HLA-C*12, and KIR3DS1 were identified as predictive factors for SR, with percentages of 77.4%, 85.7% and 86.2%, respectively, for patients who did not experience SR. The presence of at least one of these three markers, defined as a genetically unfavorable profile (GUP), combined with the IFNL3 non-CC genotype showed a value of 100% for non-SR. The absence of the three markers, defined as a genetically favorable profile (GFP), in addition to the IFNL3 CC genotype showed a percentage of 74.1% for SR. The combination of these markers in addition to the IFNL3 genotype improves the predictive value of IFNL3 for SR of acute HCV infection in HIV patients, which would be clinically valuable.

Confirmed the full-length sequence of HLA-B*44:03:02 by cloning and sequencing in a Chinese donor.

We sought to determine the prevalence and clinical and laboratory associations of fibromyalgia in adults with primary immunodeficiency (immunoglobulin (Ig) G subclass deficiency (IgGSD) and common variable immunodeficiency (CVID).We performed a retrospective analysis of these observations in 300 non-Hispanic white adult index patients with recurrent/severe respiratory tract infections and IgGSD or CVID: age; sex; IgGSD; fibromyalgia; chronic fatigue; autoimmune conditions (ACs); interstitial cystitis (IC); diabetes; body mass index; serum Ig isotypes; blood lymphocytes and subsets; and human leukocyte antigen (HLA)-A and -B types and haplotypes. We performed univariate comparisons, logistic multivariable regressions, and an analysis of covariance.Mean age was 49 ± 12 (standard deviation) y. There were 246 women (82.0%). IgGSD was diagnosed in 276 patients (92.0%). Fifty-six patients had fibromyalgia (18.7%; female:male 13:1). Other characteristics included: chronic fatigue, 63.0%; aggregate ACs, 35.3%; Sjögren's syndrome, 8.0%; IC, 3.0%; diabetes, 10.3%; and HLA-A*29, B*44 positivity, 9.7%. Prevalences of female sex; chronic fatigue; IC; and HLA-A*29, B*44 positivity were greater in patients with fibromyalgia. Logistic regression on fibromyalgia revealed three positive associations: chronic fatigue (p=0.0149; odds ratio 2.6 [95% confidence interval 1.2, 5.6]); Sjögren's syndrome (p=0.0004; 5.2 [2.1, 13.2]); and IC (p=0.0232; 5.7 [1.3, 25.7]). In an analysis of covariance, there were significant interactions of chronic fatigue, Sjögren's syndrome, and interstitial cystitis on fibromyalgia.Fibromyalgia is common in non-Hispanic white adult index patients with primary immunodeficiency, especially women. Chronic fatigue, Sjögren's syndrome, and IC are significantly associated with fibromyalgia after adjustment for other independent variables.

Background. Human leucocyte antigens (HLAs) modulate immunity to polyomavirus BK (BKV). Identification of HLAs that alter the course of infection will facilitate risk stratification, and customization of pre-emptive intervention strategies. Methods. We performed a retrospective cohort study with 998 kidney transplant patients with BKV infection status confirmed by polymerase chain reaction (PCR). Clinical parameters and donor–recipient matching for specific HLAs were examined in relation to occurrence of viremia. An emphasis was placed on donor–recipient matching rather than the actual frequency of specific HLA-alleles, since a successful immune response requires sharing of HLAs between a virusinfected target cell and the anti-viral effector cell. Results. Using multivariate statistics, low risk of BK viremia was associated with matching of HLA-A2 [hazard ratio (HR) 0.51, 95% confidence interval (CI) 0.28–0.85], HLA-B44 (HR 0.31, 95% CI 0.076–0.85) and HLA-DR15 (HR 0.35, 95% CI 0.084–0.93) (P < 0.05), whereas high risk of viremia was associated with male gender (HR 2.38, 95% CI 1.46–4.09, P < 0.001). Conclusions. HLAs that associated with a lower predisposition to the development of BK viremia have been identified. Evaluation of donor–recipient mismatching for these HLAs could potentially be used to (i) fine tune virus screening strategies for BKV in individual patients and (ii) facilitate discovery of major histocompatibility complex (MHC) class I and II binding peptides that can elicit clinically meaningful BKVspecific immunity.

Class I HLAs generally present peptides of 8–10 aa in length, although it is unclear whether peptide length preferences are affected by HLA polymorphism. In this study, we investigated the CD8+ T cell response to the BZLF1 Ag of EBV, which includes overlapping sequences of different size that nevertheless conform to the binding motif of the large and abundant HLA-B*44 supertype. Whereas HLA-B*18:01+ individuals responded strongly and exclusively to the octamer peptide 173SELEIKRY180, HLA-B*44:03+ individuals responded to the atypically large dodecamer peptide 169EECDSELEIKRY180, which encompasses the octamer peptide. Moreover, the octamer peptide bound more stably to HLA-B*18:01 than did the dodecamer peptide, whereas, conversely, HLA-B*44:03 bound only the longer peptide. Furthermore, crystal structures of these viral peptide–HLA complexes showed that the Ag-binding cleft of HLA-B*18:01 was more ideally suited to bind shorter peptides, whereas HLA-B*44:03 exhibited characteristics that favored the presentation of longer peptides. Mass spectrometric identification of > 1000 naturally presented ligands revealed that HLA-B*18:01 was more biased toward presenting shorter peptides than was HLA-B*44:03. Collectively, these data highlight a mechanism through which polymorphism within an HLA class I supertype can diversify determinant selection and immune responses by varying peptide length preferences.

HLA class I alleles have been shown to have differential impacts on the viral load and the outcome of HIV-1 disease progression. In this study, HLA class I types from residents of China with acute HIV-1 infection, diagnosed between 2006 and 2011, were identified and the association between expression of individual HLA alleles and the level of the set point viral load was analyzed. A lower level of set point viral load was found to be associated with the Bw4 homozygote on HLA-B alleles. B*44 and B*57 alleles have also been found to be associated with lower set point viral load. The set point viral load of B*44-positive individuals homozygous for Bw4 was significantly lower than that of B*44-negative individuals homozygous for Bw4 (P= 0.030). The CD4 count declined to X2= 7.295,P= 0.026). B*44-positive individuals had a lower magnitude of p24 pool-specific T cell responses than B*44-negative individuals homozygous for Bw4, though this was not statistically significant. The p24 pool-specific T cell responses were also inversely correlated with lower viral load (rs= −0.88,P= 0.033). Six peptides within p24 were recognized to induce the specific-T cell response in B*44-positive individuals, and the peptide breadth of response was same as that in B*44-negative individuals homozygous for Bw4, but the median magnitude of specific-T cell responses to the recognized peptides in B*44-positive individuals was lower than that in B*44-negative individuals homozygous for Bw4 (P= 0.049). These findings imply that weak p24-specific CD8+T cell responses might play an important role in the control of HIV viremia in B*44 allele-positive individuals. Such studies might contribute to the development of future therapeutic strategies that take into account the genetic background of the patients.

Immunogenetic information is provided on five novel alleles with synonymous mutations.

B*44:237N differs from B*44:03:01 by nucleotides deletion at nucleotide 286 and 287 in exon 2.

To characterize the association between major histocompatibility complex (MHC) types and spontaneous antibody development to the cancer testis (CT) antigen NY-ESO-1.Tumor expression of NY-ESO-1 and serum antibodies to NY-ESO-1 were characterized in addition to human leukocyte antigen (HLA) type for patients with epithelial ovarian cancer. HLA types were assigned to structure-based superfamilies and statistical associations were examined. HLA types were compared to existing reference libraries of HLA frequencies in a European-Caucasian American population.Out of 126 patients identified, 81% were expression positive and 48% had spontaneous antibody responses to NY-ESO-1. There was an association between HLA-B superfamily and seropositivity among patients with tumors expressing NY-ESO-1 (p0.001). The differences in HLA-B superfamily assignment were driven by HLA-B44. Among all patients, the B27 superfamily was over-represented compared with the general population (p0.001).HLA type appears to be associated with spontaneous anti-CT antigen antibodies, as well as with the overall risk of ovarian cancer.

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.

Major histocompatibility complex (MHC) class I molecules present cell internally derived peptides at the plasma membrane for surveillance by cytotoxic T lymphocytes. The surface expression of most class I molecules at least partially depends on the endoplasmic reticulum protein, tapasin, which helps them to bind peptides of the right length and sequence. To determine what makes a class I molecule dependent on support by tapasin, we have conducted in silico molecular dynamics (MD) studies and laboratory experiments to assess the conformational state of tapasin-dependent and -independent class I molecules. We find that in the absence of peptide, the region around the F pocket of the peptide binding groove of the tapasin-dependent molecule HLA-B*44:02 is in a disordered conformational state and that it is converted to a conformationally stable state by tapasin. This novel chaperone function of tapasin has not been described previously. We demonstrate that the disordered state of class I is caused by the presence of two adjacent acidic residues in the bottom of the F pocket of class I, and we suggest that conformational disorder is a common feature of tapasin-dependent class I molecules, making them essentially unable to bind peptides on their own. MD simulations are a useful tool to predict such conformational disorder of class I molecules.

HIV-1–specific CTL responses play a key role in limiting viral replication. CTL responses are sensitive to viral escape mutations, which influence recognition of the virus. Although CTLs have been shown to recognize epitope variants, the extent of this cross-reactivity has not been quantitatively investigated in a genetically diverse cohort of HIV-1–infected patients. Using a novel bioinformatic binding prediction method, we aimed to explain the pattern of epitope-specific CTL responses based on the patients’ HLA genotype and autologous virus sequence quantitatively. Sequences covering predicted and tested HLA class I-restricted epitopes (peptides) within the HIV-Gag, Pol, and Nef regions were obtained from 26 study subjects resulting in 1492 patient-specific peptide pairs. Epitopes that were recognized in ELISPOT assays were found to be significantly more similar to the autologous virus than those that did not elicit a response. A single substitution in the presented epitope decreased the chance of a CTL response by 40%. The impact of sequence similarity on cross-recognition was confirmed by testing immune responses against multiple variants of six selected epitopes. Substitutions at central positions in the epitope were particularly likely to result in abrogation of recognition. In summary, the presented data demonstrate a highly restricted promiscuity of HIV-1–specific CTL in the recognition of variant epitopes. In addition, our results illustrate that bioinformatic prediction methods are useful to study the complex pattern of CTL responses exhibited by an HIV-1–infected patient cohort and for identification of optimal targets for novel therapeutic or vaccine approaches.

Residues within processed protein fragments bound to major histocompatibility complex class I (MHC-I) glycoproteins have been considered to function as a series of “independent pegs” that either anchor the peptide (p) to the MHC-I and/or interact with the spectrum of αβ-T-cell receptors (TCRs) specific for the pMHC-I epitope in question. Mining of the extensive pMHC-I structural database established that many self- and viral peptides show extensive and direct interresidue interactions, an unexpected finding that has led us to the idea of “constrained” peptides. Mutational analysis of two constrained peptides (the HLA B44 restricted self-peptide (B44DPα–EEFGRAFSF) and an H2-D b restricted influenza peptide (D b PA, SSLENFRAYV) demonstrated that the conformation of the prominently exposed arginine in both peptides was governed by interactions with MHC-I-orientated flanking residues from the peptide itself. Using reverse genetics in a murine influenza model, we revealed that mutation of an MHC-I-orientated residue (SSLEN F RAYV → SSLEN A RAYV) within the constrained PA peptide resulted in a diminished cytotoxic T lymphocyte (CTL) response and the recruitment of a limited pMHC-I specific TCR repertoire. Interactions between individual peptide positions can thus impose fine control on the conformation of pMHC-I epitopes, whereas the perturbation of such constraints can lead to a previously unappreciated mechanism of viral escape.

Chronic spontaneous urticaria (CSU) is the most common form of chronic urticaria. A considerable amount of data supports an immunological basis for CSU. Some research has focused on the association between chronic urticaria and specific human leukocyte antigen (HLA) alleles. The aim of this study was to investigate the HLA status of Polish patients diagnosed with CSU. Methods: The standard complement-dependent microlymphocytotoxicity assay and PCR amplification with sequence-specific primers were used to analyze HLA alleles in 115 patients diagnosed with CSU, and the results were compared to those from 162 healthy, genetically unrelated individuals. Results: Among the HLA-A alleles, A-33 occurred significantly more often in the control group (p < 0.01). Analysis of the HLA-B allele frequencies revealed the prevalence of the B44 antigen in the study group (p < 0.0001). Frequencies of HLA-C alleles and HLA-DQ did not differ significantly between the groups. Among the HLA class II alleles, DRB1*04 was observed significantly more often in the study population (p < 0.001), mainly in the autoimmunological subtype of urticaria. Conclusion: HLA alleles may be involved in CSU development or play a protective role in CSU.

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.

Contains fulltext : 71202.pdf (Publisher’s version ) (Closed access) Minor histocompatibility antigens (mHAgs) constitute the target antigens of the T cell-mediated graft-versus-leukemia response after HLA-identical allogeneic stem cell transplantation (SCT). Several human mHAgs have been identified, but only a few are selectively expressed by hematopoietic cells representing potential targets for specific immunotherapy. Molecular approaches including cDNA library screening and genetic linkage analysis have been successfully applied to identify T cell-defined mHAgs, but each approach has its drawbacks which may lead to mis-identification of the mHAg of interest. We improved both molecular strategies to facilitate more robust identification of hematopoietic-restricted mHAgs. First, we adapted cDNA library cloning by using 293T cells with stable expression of the relevant MHC class I allele, CD80 and CD54. We demonstrated that cDNA library screening using this 293T expression system results in strong activation of cytotoxic T lymphocytes, which significantly contributes to improvement of the assay sensitivity. Second, we refined genetic linkage analysis using single nucleotide polymorphism (SNP) genotyping to narrow down the defined genetic region that holds the mHAg-encoding gene. We showed that SNP marker analysis provides additional information about the genetic position of the antigen-encoding gene. Application of these optimized molecular approaches will lead to more rapid and reliable molecular identification of hematopoietic-restricted mHAgs.

Here we report the identification of a novel human leukocyte antigen (HLA)-B44–restricted minor histocompatibility antigen (mHA) with expression limited to hematopoietic cells. cDNA expression cloning studies demonstrated that the cytotoxic T lymphocyte (CTL) epitope of interest was encoded by a novel allelic splice variant of HMSD, hereafter designated as HMSD-v. The immunogenicity of the epitope was generated by differential protein expression due to alternative splicing, which was completely controlled by 1 intronic single-nucleotide polymorphism located in the consensus 5′ splice site adjacent to an exon. Both HMSD-v and HMSD transcripts were selectively expressed at higher levels in mature dendritic cells and primary leukemia cells, especially those of myeloid lineage. Engraftment of mHA+ myeloid leukemia stem cells in nonobese diabetic/severe combined immunodeficient (NOD/SCID)/γcnull mice was completely inhibited by in vitro preincubation with the mHA-specific CTL clone, suggesting that this mHA is expressed on leukemic stem cells. The patient from whom the CTL clone was isolated demonstrated a significant increase of the mHA-specific T cells in posttransplantation peripheral blood, whereas mHA-specific T cells were undetectable in pretransplantation peripheral blood and in peripheral blood from his donor. These findings suggest that the HMSD–v–encoded mHA (designated ACC-6) could serve as a target antigen for immunotherapy against hematologic malignancies.

Background. T-cell responses to minor histocompatibility antigens are mediators of graft-versus-host disease and organ graft rejection. We previously identified a human minor histocompatibility antigen that is recognized by CD8+ cytotoxic T lymphocytes (CTLs) and encoded by the UDP glycosyltransferase 2 family, polypeptide B17 (UGT2B17) gene, which is highly expressed in the liver, colon, and small intestine. The UGT2B17 is presented by human leukocyte antigen (HLA)-A*2902, and the immunogenicity of this minor histocompatibility antigen results from differential protein expression in donor and recipient cells as a consequence of a UGT2B17 gene deletion. Methods. An HLA-B*4403-restricted CD8+ CTL clone was isolated from the same hematopoietic stem cell transplant recipient that exhibited an HLA-A*2902-restricted UGT2B17-specific response. The minor histocompatibility antigen recognized by the HLA-B*4403-restricted clone was identified, and the ability of the peptide to be presented by HLA-B*4402 was examined. Results. The HLA-B*4403-restricted CTL clone recognized a peptide encoded by UGT2B17, which is identical to the peptide presented by HLA-A*2902. Peptide binding assays revealed this UGT2B17 peptide binds with comparable affinity to HLA-B*4402 as to HLA-B*4403. This patient had acute graft-versus-host disease involving liver and gastrointestinal tract, suggesting the T-cell response directed against UGT2B17 is involved in graft-versus-host disease. Conclusions. A single peptide encoded by UGT2B17 can be presented by HLA-A*2902, B*4402 and B*4403, and may serve as an immunodominant minor histocompatibility antigen in individuals with these HLA alleles that undergo transplantation of stem cells or organ grafts from UGT2B17 disparate donors.

BACKGROUND: There has been controversy over whether HLA alloimmunization is a risk factor for platelet (PLT) transfusion refractoriness (PTR) in hematopoietic peripheral blood progenitor cell transplantation (HPBPCT). STUDY DESIGN AND METHODS: Reported here is a boy with relapsed leukemia who developed fatal PTR after a peripheral blood progenitor cell transplantation (PBPCT) as a second HPBPCT from his mother. To elucidate the cause of PTR, a single-antigen assay (FlowPRA, One Lambda), a magnetic particles mixed passive hemagglutination test, and anti-human immunoglobulin-lymphocyte cytotoxicity test were performed on serum samples of the patient and his mother. RESULTS: Although HLA Class I antibodies were absent in his serum sample before HPBPCT, the serum sample after the first bone marrow transplantation (BMT) reacted weakly with beads coated with multiple HLA Class I molecules. After PBPCT, the positive reaction markedly increased. Although HLA-B44 antibody emerged transiently after BMT, the apparent generation of antibodies against HLA-A2 and -A24 as well as HLA-B44 occurred after PBPCT. The continuous appearance of HLA Class I antibodies coincided with the duration of marked PTR after PBPCT. The patient, however, had no antibodies against PLT-specific glycoproteins. Unidentified HLA Class I–reactive antibodies were detected in maternal serum sample. CONCLUSION: Although the patient appeared to be immunized to allogeneic HLA Class I molecules after BMT, profound HLA alloimmunization might have occurred after PBPCT in this case. It is possible that the administration of large numbers of immunocompetent cells sensitive to alloantigens at PBPCT causes the aberrant and persistent production of the HLA Class I antibodies.

The selection of peptides for presentation at the surface of most nucleated cells by major histocompatibility complex class I molecules (MHC I) is crucial to the immune response in vertebrates. However, the mechanisms of the rapid selection of high affinity peptides by MHC I from amongst thousands of mostly low affinity peptides are not well understood. We developed computational systems models encoding distinct mechanistic hypotheses for two molecules, HLA-B*44:02 (B*4402) and HLA-B*44:05 (B*4405), which differ by a single residue yet lie at opposite ends of the spectrum in their intrinsic ability to select high affinity peptides. We used in vivo biochemical data to infer that a conformational intermediate of MHC I is significant for peptide selection. We used molecular dynamics simulations to show that peptide selector function correlates with protein plasticity, and confirmed this experimentally by altering the plasticity of MHC I with a single point mutation, which altered in vivo selector function in a predictable way. Finally, we investigated the mechanisms by which the co-factor tapasin influences MHC I plasticity. We propose that tapasin modulates MHC I plasticity by dynamically coupling the peptide binding region and {\alpha}3 domain of MHC I allosterically, resulting in enhanced peptide selector function.

Pre-clinical studies have shown that injection of allogeneic T cells primed against a single minor histocompatibility antigen (MiHA) could cure hematologic cancers (HC) without causing any toxicity to the host. However, translation of this approach in humans has been hampered by the paucity of molecularly defined human MiHAs. Using a novel proteogenomic approach, we have analyzed cells from 13 volunteers and discovered a vast repertoire of MiHAs presented by the most common HLA haplotype in European Americans: HLA-A*02:01;B*44:03. Notably, out of >6000 MiHAs, we have identified a set of 39 MiHAs that share optimal features for immunotherapy of HCs. These 'optimal MiHAs' are coded by common alleles of genes that are preferentially expressed in hematopoietic cells. Bioinformatic modeling based on MiHA allelic frequencies showed that the 39 optimal MiHAs would enable MiHA-targeted immunotherapy of practically all HLA-A*02:01;B*44:03 patients. Further extension of this strategy to a few additional HLA haplotypes would allow treatment of almost all patients.

The peptide-loading complex plays a pivotal role in Ag processing and is thus central to the efficient immune recognition of virally and malignantly transformed cells. The underlying mechanism by which MHC class I (MHC I) molecules sample immunodominant peptide epitopes, however, remains poorly understood. In this article, we delineate the interaction between tapasin (Tsn) and MHC I molecules. We followed the process of peptide editing in real time after ultra-fast photoconversion to pseudoempty MHC I molecules. Tsn discriminates between MHC I loaded with optimal and MHC I bound to suboptimal cargo. This differential interaction is key to understanding the kinetics of epitope proofreading. To elucidate the underlying mechanism at the atomic level, we modeled the Tsn/MHC I complex using all-atom molecular dynamics simulations. We present a catalytic working cycle, in which Tsn binds to MHC I with suboptimal cargo and thereby adjusts the energy landscape in favor of MHC I complexes with immunodominant epitopes.

The genomic sequence of the novel HLA-B*44:220 allele identified in a British Caucasoid male.

A panel of cytolytic T lymphocyte (CTL) clones was isolated from metastases and blood samples of a melanoma patient vaccinated with MAGE-3.A1-pulsed autologous dendritic cells. We report here the identification of a new antigen encoded by the MAGE-C2 cancer-germline gene. This antigen is recognized by some of these CTL on HLA-B*4403. The sequence of the peptide is SESIKKKVL. It is processed in various melanoma cell lines expressing MAGE-C2 and HLA-B*4403. Because of the expression pattern of gene MAGE-C2, this new antigen is strictly tumor-specific and could therefore be used for peptide-based antitumoral vaccination.

To test whether MHC alleles associated with common variable immune deficiency (CVID) might also be over-represented in patients with normal serum immunoglobulin levels who suffer with recurrent sinopulmonary infections (RESPI), we identified 62 consecutive RESPI patients and compared their HLA-B and HLA-DR antigen frequencies to those of 60 consecutive patients with CVID, 1627 Alabama Caucasian bone marrow donors, and 997,230 published US Caucasians. Either HLA-B44, -B8, -DR3(17), or -DR7 was present in 74% of the RESPI and 85% of the CVID patients. HLA-B44 prevalence in particular proved identical between RESPI and CVID. When compared to US Caucasians, the increased prevalence of the four HLA alleles proved significant at P < 0.0001, P < 0.0001, P = 0.0005, and P = 0.02, respectively. When compared to Alabama Caucasians, only the increased prevalence of HLA-B44 achieved statistical significance (P = 0.0001). Inheritance of HLA-B44 may yield susceptibility to recurrent sinopulmonary infection even in the presence of normal serum immunoglobulin levels.

A novel HLA-B (human leukocyte antigen-B) allele, HLA-B*4442, was identified both in a Czech patient with leukaemia and in his mother. The presence of a novel allele was initially suspected because conflicting results were obtained by serological and DNA typing techniques. The HLA typing using the polymerase chain reaction-sequence-specific primers (PCR-SSP) at the two-digit level indicated an allele belonging to the HLA-B*44 group, whereas serological typing indicated HLA-B21. Typing with PCR-sequence-specific oligonucleotides (PCR-SSO) resulted in a unique reaction pattern that could not be assigned to a known allele, PCR-SSP typing at the four-digit level did not match any known B*44 allele, either. The sequencing-based typing of the HLA-B locus then revealed the novel B*4442 allele that is identical with B*4405 except a single C-->G nucleotide exchange at position 572. This exchange results in an amino acid substitution from serine to tryptophan at position 167 of the expressed HLA-B protein. The B21 serological reactivity of the novel B*4442 allele product was confirmed by employing an additional serological panel of typing sera. Our findings support previous reports claiming that serine at the position 167 in the alpha-2 domain of the HLA-B protein is a major determinant of the HLA-B44(12) serological epitope.

Autoimmune lymphoproliferative syndrome (ALPS) is a disorder of lymphocyte apoptosis characterized by non-malignant lymphadenopathy and splenomegaly, expansion of T cells without either CD4 or CD8 surface markers, and increased incidence of autoimmune diseases and lymphoma. Most patients with ALPS have dominant, heterozygous mutations in tumor necrosis factor receptor superfamily member 6 (TNFRSF6), which encodes CD95, also known as Fas, a mediator of apoptosis. Penetrance and range of disease manifestations in ALPS are highly variable, even among family members who share the same dominant TNFRSF6 mutation. To evaluate HLA as a candidate modifier locus, we typed HLA A, B (including subtypes), and DQB alleles in 356 individuals from 63 unrelated families with defined TNFRSF6 mutations associated with ALPS. We also developed a quantitative severity score and performed statistical analysis. Among the healthier, mutation-bearing individuals, transmission of HLA B44 was significantly overrepresented (nominal P

Based on high-resolution DNA typing within 235 pedigrees, a total of 250 HLA-A/B/C/DRB1/DRB3 genotypes have been characterized. These comprise 129 different B44 haplotypes, of which 73.6% occurred only once. Only four different B*44 alleles were identified: B*4402-4405, with B*4402 and B*4403 haplotypes accounting for 57.6 and 36.8%, respectively, of all haplotypes. Although the relative numbers of different A/B/C/DRB1/B3 haplotypic associations were similar in both B*4402 and B*4403 haplotypes, the genotypic profiles were quite different in the two groups. When associated with the A*0101, A*0201, A*2402, A*3201, and A*6801 alleles, a much more extensive polymorphism of B*4402 haplotypes with respect to HLA-C and DRB1 associations was disclosed. On the other hand, B*4403 haplotypes were more diverse in the A23-B44 and A29-B44 groups with respect to DRB1 associations. Considering B-C linkage, B*4402-Cw*0501, B*4402-Cw*0704, B*4402-Cw*1604, B*4403-Cw*0401, B*4403-Cw*1601, B*4404-Cw*1601, and B*4405-Cw*0202 accounted for 98% of all genotypes. Eight A/B/C/DRB1 haplotypes occurred at a relative genotypic frequency of >0.015, with A*2902-B*4403-Cw*1601-DRB1*0701 (11.2%) and A*0201-B*4402-Cw*0501-DRB1*0401 (8.4%) as the two most frequent genotypes. Some A and DRB1 alleles were predominantly, if not exclusively, associated with specific B-C pairs: A*0301 with B*4402-Cw*0501 and B*4403-Cw*0401; A*2301 with B*4403-Cw*0401; A*2608 with B*4402-Cw*0501; A*2902 with B*4403-Cw*1601; DRB1*0101/0401/0403/0404/1101/1104/0801/1301/1302 with B*4402-Cw*0501; and DRB1*0701 with B*4403-Cw*1601. On the basis of this dataset and our experience with searches for phenotypically matched unrelated stem cell donors, several ABDR haplotypes were identified that would confer a higher probability of B44- and C-incompatibility. The analysis of 112 consecutive unrelated stem cell donor searches revealed that 24% of the 400 tested donors were B44-mismatched, and that no single B44 allele- matched donor could be identified for only 7% of the patients. HLA-C incompatibility rate was 22.2% for the patients with > or =1 B44 allele-matched donor(s). This dataset can therefore be used as a predictive tool for B44- and C-disparities in unrelated stem cell transplantation.

HLA-B*4402 and B*4403 are naturally occurring MHC class I alleles that are both found at a high frequency in all human populations, and yet they only differ by one residue on the α2 helix (B*4402 Asp156→B*4403 Leu156). CTLs discriminate between HLA-B*4402 and B*4403, and these allotypes stimulate strong mutual allogeneic responses reflecting their known barrier to hemopoeitic stem cell transplantation. Although HLA-B*4402 and B*4403 share >95% of their peptide repertoire, B*4403 presents more unique peptides than B*4402, consistent with the stronger T cell alloreactivity observed toward B*4403 compared with B*4402. Crystal structures of B*4402 and B*4403 show how the polymorphism at position 156 is completely buried and yet alters both the peptide and the heavy chain conformation, relaxing ligand selection by B*4403 compared with B*4402. Thus, the polymorphism between HLA-B*4402 and B*4403 modifies both peptide repertoire and T cell recognition, and is reflected in the paradoxically powerful alloreactivity that occurs across this “minimal” mismatch. The findings suggest that these closely related class I genes are maintained in diverse human populations through their differential impact on the selection of peptide ligands and the T cell repertoire.

In this issue, Singh and co-workers describe the results of classical typing of human leukocyte antigen (HLA) alleles in 1,404 vitiligo patients and 902 unaffected controls from North India and follow-up HLA typing in 355 cases and 441 controls from Gujarat. The increased frequency of DRB1*07:01 in North Indian and Gujarat populations with generalized and localized vitiligo and in several vitiligo populations studied previously suggests that it contributes to autoimmunity and destruction of melanocytes.

Herpes zoster is a common disease caused by reactivation of the varicella zoster virus (VZV). In a small number of herpes zoster patients, pain persists beyond 4 weeks or more after healing of vesicular eruptions; this condition is termed postherpetic neuralgia (PHN). Positive associations of human histocompatibility leukocyte antigens (HLA) class I antigens, A33 and B44, with PHN in the Japanese population have been reported. Our hypothesis is that susceptibility genes to PHN might exist in the HLA region and the study objective is to further examine possible associations of genes in HLA class I, II and III regions, HLA-A, -B, -DRB1, tumor necrosis factor alpha (TNFA) promoter, and a natural killer cell activating receptor, NKp30 polymorphisms with PHN. Although TNFA or NKp30 in the class III region had been considered as a candidate locus, we found no associations of TNFA promoter or NKp30 polymorphisms with PHN in this study. We demonstrated that HLA-A*3303, -B*4403 and -DRB1*1302 alleles were significantly associated with PHN (P = 0.0007 for A*3303, P = 0.001 for B*4403 and P = 0.001 for DRB1*1302). The frequency of the HLA-A*3303-B*4403-DRB1*1302 haplotype was also significantly higher in the PHN patients than in the healthy controls (P = 0.0039). Our results suggest that this haplotype might be related to the pathogenesis of PHN.

A naturally processed and presented ligand that is shared by human leukocyte antigen (HLA) B*4402, B*4403 and B*4405 molecules has been identified in peptides isolated from immunoaffinity purified HLA B44 complexes. This peptide derived from HLA DPalpha residues 46-54, an endogenous product of HLA DP expressed in the cell line Hmy2.C1R, is a prominent peptide in the mass spectra of species isolated as bound peptides from each allele when the three HLA B44 subtypes were introduced as transfected gene products. Recombinant truncated forms of HLA B*4405(1-276), HLA B*4403(1-276), HLA B*4402(1-276) and beta(2)-microglobulin have been prepared as inclusion bodies in Escherichia coli and refolded in the presence of the DPalpha(46-54) peptide and purified by a combination of size exclusion and anion exchange chromatography. This material was determined to be correctly folded based on detection of a conformational epitope recognized by the W6/32 monoclonal antibody. Large, plate-like crystals of the three complexes were produced using polyethylene glycol as the precipitant. All the crystals belong to the space group P2(1)2(1)2(1) with unit cell dimensions of approximately a=51, b=82, c=110 A. The crystals of three B44/DPalpha complexes diffracted to a resolution of 1.9 A or better. For the first time, using this natural, high abundance ligand of the HLA B44 molecules we have successfully expressed and refolded the three HLA B44 molecules and produced crystals amenable to structural studies.

Purpose: Spondyloarthropathy includes the subcategory of reactive arthritis (ReA). Spondyloarthropathies are commonly associated with certain human leukocyte antigen (HLA) alleles. Because we identified bacteria associated with ReA within the temporomandibular joint (TMJ), we now evaluate the frequency of HLA alleles in patients with TMJ pathology. Patients and methods: HLA typing of 129 patients (121 females and 8 males) performed by standard microcytotoxicity technique. Thirty patients had only class I (HLA-A and -B loci) evaluated. Ninety-nine patients had both class I and class II (HLA-DR loci) evaluated. Identification of alleles at the C locus was not performed. The antigenic frequency in the study group was compared to US white control subjects using a 2-tailed Fisher's exact test with a Bonferroni multiple comparison adjustment. Results: The following class I HLA alleles, -A1 (32%), -A2 (50%), -A3 (33%), -B7 (23%), -B14 (14%), -B35 (20%), and -B44 (36%), including the B7 cross-reactive group (CREG) (49%) and class II alleles -DR1 (25%) and -DR4 (34%), were found to have an increased frequency in our patient group. Conclusions: Our study shows an increased frequency of several alleles that have been previously associated with arthropathy, and the alleles of the B7 CREG, in patients with TMJ pathology. Patients with these alleles may have an increased risk for the development of internal derangement of the TMJ as a consequence of the bacterial/infectious agents and host interactions with the subsequent cytokine/inflammatory response being influenced by their HLA phenotype. © 2002 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 60:778-783, 2002

The loading of MHC class I molecules with their peptide cargo is undertaken by a multimolecular peptide loading complex within the endoplasmic reticulum. We show that MHC class I molecules can optimize their peptide repertoire over time and that this process is dependent on tapasin. Optimization of the peptide repertoire is both quantitatively and qualitatively improved by tapasin. The extent of optimization is maximal when MHC class I molecules are allowed to load within the fully assembled peptide loading complex. Finally, we identify a single natural polymorphism (116D>Y) in HLA-B*4402 that permits tapasin-independent loading of HLA-B*4405 (116Y). In the presence of tapasin, the tapasin-independent allele B*4405 (116Y) acquires a repertoire of peptides that is less optimal than the tapasin-dependent allele B*4402 (116D).

Stevens-Johnson syndrome (SJS) and its severe variant, toxic epidermal necrolysis (TEN), are acute inflammatory vesiculobullous reactions of the skin and mucous membranes. Cold medicines including non-steroidal anti-inflammatory drugs and multi-ingredient cold medications are reported to be important inciting drugs. Recently, we reported that cold medicine related SJS/TEN (CM-SJS/TEN) with severe mucosal involvement including severe ocular surface complications (SOC) is associated with HLA-A*02:06 and HLA-B*44:03 in the Japanese. In this study, to determine whether HLA-B*44:03 is a common risk factor for CM-SJS/TEN with SOC in different ethnic groups we used samples from Indian, Brazilian, and Korean patients with CM-SJS/TEN with SOC, and investigated the association between CM-SJS/TEN with SOC and HLA-B*44:03 and/or HLA-A*02:06. We found that HLA-B*44:03 was significantly associated with CM-SJS/TEN with SOC in the Indian and Brazilian but not the Korean population, and that HLA-A*02:06 might be weakly associated in the Korean- but not the Indian and Brazilian population.