Major Histocompatibility Complex Class I Chain-Related A and B (MICA and MICB) Gene, Allele, and Haplotype Associations With Dengue Infections in Ethnic Thais.

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.

Influence of HLA-B18 on liver fibrosis progression in a cohort of HIV/HCV coinfected individuals.

Liver fibrosis is accelerated in human immunodeficiency virus/hepatitis C virus (HIV/HCV) coinfected compared with HCV monoinfected patients, due to multiple cofactors. Recently, HLA-B18 haplotype has been associated with short-term liver disease progression in this population. Our aim was to assess the influence of HLA-B18 on the fibrosis process in HIV/HCV coinfected individuals, untreated for HCV, during a long-term follow-up. All consecutive HIV/HCV co-infectedcoinfected patients followed in our center, with positive HCV-RNA and available human leukocyte antigen (HLA) haplotypes (determined by sequence-specific oligonucleotide primed polymerase chain reaction and simple sequence repeats polymerase chain reaction using Luminex Technology) were included. Liver fibrosis progression was assessed by means of fibrosis-4 index for liver fibrosis (FIB-4) and AST to platelet ratio index. The association between FIB-4 score over time and laboratory and clinical parameters, including HLA, was evaluated by univariate and multivariate multilevel generalized linear models. A total of 29 out of 148 screened patients were excluded because of spontaneous HCV clearance (27% were HLA-B18+). Among the remaining 119 individuals (82% males; median age at first visit = 30 years [interquartile range, IQR, 26-35]; median follow-up = 21.5 years [IQR, 15-25]), 26% were HLA-B18+. No baseline differences were evidenced between HLA-B18+ and B18- patients. Fibrosis progression was significantly faster in HLA-B18+ than in HLA-B18- patients ( P < 0.001) (Figure 1). At univariate analysis, age ( P < 0.001), HLA-B18 haplotype ( P = 0.02) and HIV-RNA viral load overtime ( P < 0.001) were associated with liver disease progression. At multivariate analysis, only age ( P < 0.001) remained independently associated with liver fibrosis progression. Our data suggest a possible association between HLA-B18 and an accelerated liver fibrosis in HIV/HCV coinfected with a long-term follow-up.

HLA-B18 as a risk factor of short-term progression to severe liver fibrosis in HIV/HCV co-infected patients with absent or minimal fibrosis: implications for timing of therapy.

Our aim was to analyze the influence of HLA-B haplotypes on liver fibrosis progression in HIV/hepatitis C virus (HCV) co-infected patients. Retrospective longitudinal study including HIV/HCV, non-cirrhotic and HCV treatment-naïve patients. The main outcome variable was liver fibrosis progression of at least one stage. One hundred and four patients constituted the study population (F0-F1: 62 (59.6%); F2: 22 (21.2%); F3: 20 (19.2%)). During a median follow-up of 54.5 months (IQR: 26.2-77), 45 patients (43.3%) showed an increase in the stage of liver fibrosis (time to event: 29 (IQR: 14-49.5) months). HLA-B18pos patients more frequently had a higher and faster fibrosis progression rate (73.3%; 24 (IQR: 8-29) months) than HLA-B18neg patients (38.2%; 34.5 (IQR: 14.7-51.2) months). This association was also observed in the development of F3-F4 fibrosis among F0-F2 patients (HLA-B18pos: 69.2%; 18 (6.5-37) months vs HLA-B18neg: 28.2%; 37 (IQR: 19-52) months). These results could impact the timing of HCV therapy in F0-F2 patients.

HLA peptide length preferences control CD8+ T cell responses.

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 (173)SELEIKRY(180), HLA-B*44:03(+) individuals responded to the atypically large dodecamer peptide (169)EECDSELEIKRY(180), 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.

Characterisation of the novel HLA-B*18:243 allele using short- and long-read sequencing technologies.

The novel HLA-B*18:243 allele, first described in a potential bone marrow donor from Brazil.

In antibody-positive first-degree relatives of patients with type 1 diabetes, HLA-A*24 and HLA-B*18, but not HLA-B*39, are predictors of impending diabetes with distinct HLA-DQ interactions.

AIMS/HYPOTHESIS: Secondary type 1 diabetes prevention trials require selection of participants with impending diabetes. HLA-A and -B alleles have been reported to promote disease progression. We investigated whether typing for HLA-B*18 and -B*39 may complement screening for HLA-DQ8, -DQ2 and -A*24 and autoantibodies (Abs) against islet antigen-2 (IA-2) and zinc transporter 8 (ZnT8) for predicting rapid progression to hyperglycaemia. METHODS: A registry-based group of 288 persistently autoantibody-positive (Ab(+)) offspring/siblings (aged 0-39 years) of known patients (Ab(+) against insulin, GAD, IA-2 and/or ZnT8) were typed for HLA-DQ, -A and -B and monitored from the first Ab(+) sample for development of diabetes within 5 years. RESULTS: Unlike HLA-B*39, HLA-B*18 was associated with accelerated disease progression, but only in HLA-DQ2 carriers (p < 0.006). In contrast, HLA-A*24 promoted progression preferentially in the presence of HLA-DQ8 (p < 0.002). In HLA-DQ2- and/or HLA-DQ8-positive relatives (n = 246), HLA-B*18 predicted impending diabetes (p = 0.015) in addition to HLA-A*24, HLA-DQ2/DQ8 and positivity for IA-2A or ZnT8A (p ≤ 0.004). HLA-B*18 interacted significantly with HLA-DQ2/DQ8 and HLA-A*24 in the presence of IA-2 and/or ZnT8 autoantibodies (p ≤ 0.009). Additional testing for HLA-B*18 and -A*24 significantly improved screening sensitivity for rapid progressors, from 38% to 53%, among relatives at high Ab-inferred risk carrying at least one genetic risk factor. Screening for HLA-B*18 increased sensitivity for progressors, from 17% to 28%, among individuals carrying ≥ 3 risk markers conferring >85% 5 year risk. CONCLUSIONS/INTERPRETATION: These results reinforce the importance of HLA class I alleles in disease progression and quantify their added value for preparing prevention trials.

Naturally selected rilpivirine-resistant HIV-1 variants by host cellular immunity.

BACKGROUND: Rilpivirine is listed as an alternative key drug in current antiretroviral therapy (ART) guidelines. E138G/A/K in human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) are rilpivirine resistance-associated mutations and can be identified in a few ART-naive patients, although at low frequency. The 138th position in HIV-1 RT is located in one of the putative epitopes of human leukocyte antigen (HLA)-B*18-restricted cytotoxic T lymphocytes (CTLs). CTL-mediated immune pressure selects escape mutations within the CTL epitope. Here we tested whether E138G/A/K could be selected by HLA-B*18-restricted CTLs. METHODS: The amino acid variation at the 138th position was compared between ART-naive HIV-1-infected patients with and without HLA-B*18. The optimal epitope containing the 138th position was determined and the impact of E138G/A/K on CTL response was analyzed by epitope-specific CTLs. The effect of E138G/A/K on drug susceptibility was determined by constructing recombinant HIV-1 variants. RESULTS: The prevalence of E138G/A/K was 21% and 0.37% in 19 and 1088 patients with and without HLA-B*18, respectively (odds ratio, 72.3; P = 4.9 × 10(-25)). The CTL response was completely abolished by the substitution of E138G/A/K in the epitope peptide. E138G/A/K conferred 5.1-, 7.1-, and 2.7-fold resistance to rilpivirine, respectively. CONCLUSIONS: E138G/A/K can be selected by HLA-B*18-restricted CTLs and confer significant rilpivirine resistance. We recommend drug resistance testing before the introduction of rilpivirine-based ART in HLA-B*18-positive patients.

Distribution of HLA class I and II genes in ankylosing spondylitis patients from Morocco.

OBJECTIVES: In Morocco, the patients affected by ankylosing spondylitis (AS) presents a high frequency of coxitis. Our study reports, for the first time, the polymorphism of Human Leukocyte Antigen (HLA) class I and class II molecules in the Moroccan patients. METHODS: Forty-six patients diagnosed with an AS and coxitis were compared to a group of 183 healthy controls matched by age, sex and ethnic origin. The HLA typing was performed using microlymphocytotoxicity for the class I (-A, -B) and PCR-SSP for the class II (-DR, -DQ). RESULTS: We found a significant increase of the HLA-B27 antigen frequency (P<0.0001, RR=20.9) in AS patients (29.3%) compared to the controls (3.2%) and a significant decrease in the frequency of HLA-B12 and HLA-B18 antigens. Examination of HLA class II distribution shows a significant increase of the HLA-DRB1*11 allele frequency in patients (P<0.0001). Concerning HLA-DQB1* alleles, no significant difference between patients and controls was appreciable. CONCLUSIONS: The HLA-B27 antigen is involved in the predisposition to the AS with coxitis in the Moroccan population. However, the low frequency observed in our population suggests the existence of other genetic and/or environmental factors. Other HLA genes seem to confer a predisposing effect (DRB*11) or a protective effect (B12 and B18) against the disease.

Impaired cytotoxic T lymphocyte recognition due to genetic variations in the main immunogenic region of the human immunodeficiency virus 1 NEF protein.

Human immunodeficiency virus (HIV) induces strong responses from human histocompatibility leukocyte antigen (HLA) class I-restricted cytotoxic T lymphocytes (CTL). In a previous report we identified an immunodominant region (amino acids 73-144) in the NEF protein that was recognized by CD8+ class I-restricted CTL of most asymptomatic individuals. Analysis of the 73-144 region by peptide sensitization, experiments using overlapping peptides corresponding to the LAI isolate identified the peptide sequences located between residues 73 and 82 or 84 and 92 and the peptide sequence between residues 134 and 144 as cognate peptides for HLA-A11- and HLA-B18-restricted epitopes, respectively. This report describes the variable demonstrable reactivities of CTL obtained from HLA-A11 or HLA-B18 seropositive, asymptomatic patients who all had a response to the virus NEF protein, but who did not always recognize appropriate cognate peptides. The high mutation rate of HIV probably facilitates the selection of mutants that can avoid the cellular immune response. We therefore analyzed the variability of these epitopes restricted by HLA-A11 and HLA-B18. We sequenced several viral isolates from HLA-A11 and HLA-B18 donors who recognized certain HLA-peptide complexes and from those who did not. A CTL sensitization assay was used to show that some mutations led to a great reduction in CTL activity in vitro. This might be due to failure of the mutated epitope to bind major histocompatibility complex class I molecule. A simple assay was used to detect peptides that promoted the assembly of class I molecules. Some of these mutations at major anchor positions prevented HLA-A11/peptide binding, and consequently impaired recognition of the HLA-peptide complex by the T cell receptor.

HLA-B*18:35, a new HLA-B*18 allele identified by sequence-based typing in a Brazilian volunteer bone marrow donor.

A novel human leukocyte antigen-B allele named B*18:35 was identified in a Brazilian volunteer bone marrow donor.

Role of human leukocyte antigen class I alleles in progressive multifocal leukoencephalopathy.

Because human leukocyte antigen (HLA) associations with various infectious diseases have recently been reported, we examined the role of HLA class I alleles in the development of progressive multifocal leukoencephalopathy (PML) or its outcome in 152 patients, including 123 Caucasians and 29 African Americans. Compared to a human immunodeficiency virus positive (HIV+) control population, we observed decreased frequency of HLA-A3 (P = 0.03) in the Caucasian PML group, whereas B18 (P = 0.02), was more frequent. No such difference was found among African American PML patients. We then sought to characterize differences in HLA between PML progressors, whose survival doesn't exceed 1 year, and survivors. Caucasian survivors were less likely to harbor A68 (P = 0.01), whereas African American survivors less frequently displayed Cw4 (P = .01). However, none of these differences reached statistical significance after Bonferroni correction for multiple testing. Further investigations are needed to assess the role of genetics in the incidence of PML or its outcome. Physicians may exercise caution in the use of immunomodulatory medications in patients whose genetic background is associated with an increased risk of PML.

The role of human leucocyte antigens in children with hydatid disease: their association with clinical condition and prognosis.

Hydatid disease (HD) is a parasitosis caused by Echinococcus granulosus, which is still an important health problem worldwide, and our country is an endemic region for HD. There is little information regarding the role of human leucocyte antigen (HLA) in genetic susceptibility or resistance to HD. In this study, we aimed to investigate the HLA profile of Turkish children with HD and to compare them with healthy individuals. We also planned to investigate whether HLAs have a potential role in the predisposition to or prevention of the occurrence of HD and to study the relationship between the clinical features of HD and the HLA profile of the patients. The study included 81 children (25 boys, 56 girls) with HD aged between 3 and 18 years. All the patients' and control subjects' HLA class I and II antigens were examined, antigen allele frequencies were calculated, and clinical characteristics were also evaluated. The frequency of HLA-B18, -DR1, and -DR15 alleles were significantly different between the patients and healthy groups; HLA-DR15 antigen might be associated with HD occurrence, and the presence of HLA-B18 and HLA-DR1 antigens might be associated with HD resistance. Compared with the healthy group, patients with lung HD had a significant increase in HLA-B44 frequency, and liver HD patients had a significant increase in HLA-DR15 antigen frequency. Furthermore, presence of HLA-DR11 was found to be a significant factor associated with cure of the disease. We concluded that HLA types have significant impact on the development of HD and clinical course of disease.

Localization of Type 1 Diabetes susceptibility in the ancestral haplotype 18.2 by high density SNP mapping.

Previous studies have suggested that the ancestral haplotype 18.2 (AH18.2) carries additional susceptibility gene to Type 1 Diabetes (T1D) on the Major Histocompatibility Complex (MHC). We analyzed 10 DR3/TNFa1b5 homozygous subjects in order to establish the conservation of the AH18.2 and then compared this conserved region with other DR3 haplotype, the AH8.1. The Illumina's HumanHap550 Bead chip was used to perform an extensive genotyping of the MHC region. The AH18.2 was highly conserved between DDR1 and HLA-DQA1 genes; therefore most probably the second susceptibility gene is located within this region. We can exclude the region centromeric to HLA-DRA gene and telomeric to DDR1 gene. A comparison between the AH18.2 and AH8.1 haplotypes showed that 233 SNPs were different in the aforementioned conserved region. These data suggest that the 1.65 Mb MHC region between DDR1 and HLA-DRA genes is likely to carry additional susceptibility alleles for T1D on the AH18.2 haplotype.

Exploring the diabetogenicity of the HLA-B18-DR3 CEH: independent association with T1D genetic risk close to HLA-DOA.

The objective of this study was to identify additional diabetes susceptibility markers in the MHC that could be responsible for the differential diabetogenicity of different HLA-DR3 CEHs. High-resolution SNP genotyping of the MHC was carried out in 15 type 1 diabetes (T1D) patients and 39 non-diabetic controls, homozygous for DR3-DQ2 and with one copy of the A(*)30-B(*)18-MICA(*)4-F1C30-DRB1(*)0301-DQB1(*)0201-DPB1(*)0202 HLA haplotype. Significantly associated SNPs were replicated in an independent sample of 554 T1D patients and 841 controls without HLA matching. Electrophoretic mobility shift assay was used to show a functional effect of an associated SNP. Seven SNPs showed evidence of association in the initial discovery experiment. Upon replication, only rs419434 (upstream HLA-DOA gene) remained significant. A functional variant (rs432375) in complete LD with rs419434 was shown to affect USF-1 binding and could be responsible for the association signal in the region. We have identified a new susceptibility locus within the MHC with a modest contribution to T1D (OR=1.93; CI: 1.52-2.44; P=10(-8)) that is independent of HLA-DRB1 locus.

Identification of the novel HLA-B*18:147 allele in two Colombian umbilical cord blood bank samples.

HLA-B*18:147 differs from HLA-B*18:01:01:01 by one nucleotide substitution.

HLA typing of patients with 21-hydroxylase deficiency in Iranian children with congenital adrenal hyperplasia.

Congenital adrenal hyperplasia (CAH) is a group of potentially life-threatening disorders, most often caused by deficiency of steroid 21-hydroxylase. Children with ambiguous genitalia, hermaphroditism, or signs and symptoms of CAH admitted to Children's Medical Center were enrolled in the survey, and 101 patients were found. Karyotyping, clinical examination, and paraclinical tests were done. HLA typing was done in patients with proven classical CAH and their parents. HLA antigens were typed in children with CAH-type 21-hydroxylase deficiency. The antigen frequencies were compared with those of the control population. The studies revealed that two HLA antigens, HLA-B18 and HLA-B21, showed a significant increase in frequency. The calculated relative risk value was high, distinguishing the population of patients and their parents. The relative risk among patients was 11.82 for HLA-B18 and 1.75 for HLA-B21 antigens. There was no relationship between HLA-DR antigens and CAH. Studies on the correlation between HLA and CAH indicate an association with HLA-B18 and HLA-B21 antigens, and they can be used as genetic markers of the disorder in the Iranian population, if they are restricted to Iranian patients.

Accelerated Progression to Type 1 Diabetes in the Presence of HLA-A*24 and -B*18 Is Restricted to Multiple Islet Autoantibody-Positive Individuals With Distinct HLA-DQ and Autoantibody Risk Profiles.

OBJECTIVE: We investigated the effect of HLA class I risk alleles on disease progression in various phases of subclinical islet autoimmunity in first-degree relatives of patients with type 1 diabetes. RESEARCH DESIGN AND METHODS: A registry-based group of siblings/offspring (aged 0-39 years) was monitored from single- to multiple-autoantibody positivity (n = 267) and from multiple-autoantibody positivity to clinical onset (n = 252) according to HLA-DQ, -A*24, -B*18, and -B*39 status. Genetic markers were determined by PCR sequence-specific oligotyping. RESULTS: Unlike HLA-B*18 or -B*39, HLA-A*24 was associated with delayed progression from single- to multiple-autoantibody positivity (P = 0.009) but not to type 1 diabetes. This occurred independently from older age (P < 0.001) and absence of HLA-DQ2/DQ8 or -DQ8 (P < 0.001 and P = 0.003, respectively), and only in the presence of GAD autoantibodies. In contrast, HLA-A*24 was associated with accelerated progression from multiple-autoantibody positivity to clinical onset (P = 0.006), but its effects were restricted to HLA-DQ8+ relatives with IA-2 or zinc transporter 8 autoantibodies (P = 0.002). HLA-B*18, but not -B*39, was also associated with more rapid progression, but only in HLA-DQ2 carriers with double positivity for GAD and insulin autoantibodies (P = 0.004). CONCLUSIONS: HLA-A*24 predisposes to a delayed antigen spreading of humoral autoimmunity, whereas HLA-A*24 and -B*18 are associated with accelerated progression of advanced subclinical autoimmunity in distinct risk groups. The relation of these alleles to the underlying disease process requires further investigation. Their typing should be relevant for the preparation and interpretation of observational and interventional studies in asymptomatic type 1 diabetes.

Cytotoxic T cell responses to multiple conserved HIV epitopes in HIV-resistant prostitutes in Nairobi.

Many people who remain persistently seronegative despite frequent HIV exposure have HIV-specific immune responses. The study of these may provide information about mechanisms of natural protective immunity to HIV-1. We describe the specificity of cytotoxic T lymphocyte responses to HIV in seronegative prostitutes in Nairobi who are apparently resistant to HIV infection. These women have had frequent exposure to a range of African HIV-1 variants, primarily clades A, C, and D, for up to 12 yr without becoming infected. Nearly half of them have CTL directed towards epitopes previously defined for B clade virus, which are largely conserved in the A and D clade sequences. Stronger responses are frequently elicited using the A or D clade version of an epitope to stimulate CTL, suggesting that they were originally primed by exposure to these virus strains. CTL responses have been defined to novel epitopes presented by HLA class I molecules associated with resistance to infection in the cohort, HLA-A*6802 and HLA-B18. Estimates using a modified interferon-gamma Elispot assay indicate a circulating frequency of CTL to individual epitopes of between 1:3,200 and 1:50,000. Thus, HIV-specific immune responses-particularly cross-clade CTL activity- may be responsible for protection against persistent HIV infection in these African women.

Full-length sequences of 3 HLA-B alleles, B*07:05:01:01, B*14:01:01 and B*18:02, confirmed by cloning and sequencing.

Full-length sequences of HLA-B*07:05:01:01, B*14:01:01 and B*18:02, confirmed by cloning and sequencing in Chinese donors.