The self-reactive FVIII T cell repertoire in healthy individuals relies on a short set of epitopes and public clonotypes.

Non-mutated FVIII-specific CD4 T cell epitopes have been recently found to contribute to the development of inhibitors in patients with hemophilia A (HA), while auto-reactive CD4 T cells specific to FVIII circulate in the blood of healthy individuals at a frequency close to the foreign protein ovalbumin. Thus, although FVIII is a self-protein, the central tolerance raised against FVIII appears to be low. In this study, we conducted a comprehensive analysis of the FVIII CD4 T cell repertoire in 29 healthy donors. Sequencing of the CDR3ß TCR region from isolated FVIII-specific CD4 T cells revealed a limited usage and pairing of TRBV and TRBJ genes as well as a mostly hydrophobic composition of the CDR3ß region according to their auto-reactivity. The FVIII repertoire is dominated by a few clonotypes, with only 13 clonotypes accounting for half of the FVIII response. Through a large-scale epitope mapping of the full-length FVIII sequence, we identified 18 immunodominant epitopes located in the A1, A3, C1, and C2 domains and covering half of the T cell response. These epitopes exhibited a broad specificity for HLA-DR or DP molecules or both. T cell priming with this reduced set of peptides revealed that highly expanded clonotypes specific to these epitopes were responsible individually for up to 32% of the total FVIII repertoire. These FVIII T cell epitopes and clonotypes were shared among HLA-unrelated donors tested and previously reported HA patients. Our study highlights the role of the auto-reactive T cell response against FVIII in HA and its similarity to the response observed in healthy individuals. Thus, it provides valuable insights for the development of new tolerance induction and deimmunization strategies.

Evaluation of HLA-DR and HLA-DQ expression in gastric cancer tissues.

BACKGROUND AND OBJECTIVES: Despite recent advances in understanding the gastric cancer (GC) biology, the precise molecular mechanism of gastric carcinogenesis and role of deregulated immune responses in GC progression are still not well understood. In this study, mRNA levels of human leukocyte antigen (HLA)-DRA and -DQA1 were assessed in GC patients to find a potential association between expression of these HLA-II molecules and gastric carcinogenesis. METHODS: Using quantitative real-time (qRT)-PCR, mRNA levels of HLA-DRA and -DQA1 were assessed in 20 pairs of matched GC and normal tissues. RESULTS: Our results showed that overall mRNA level of HLA-DRA was decreased in the tumor samples relative to control tissues (median fold change [FC] = 0.693; P = 0.445). Overall HLA-DQA1 level was increased in the tumor samples relative to control tissues (median FC = 1.659; P = 0.5117). However, the mentioned data were not statistically significant. Meanwhile, using a ≥ 2.5 FC as the cutoff to determine upregulation or downregulation, 35% of patients showed a downregulated expression of HLA-DRA, while 10% of those showed upregulation in HLA-DRA expression. Upregulation and downregulation of HLA-DQA1 expression were detected, respectively, in 35% and 25% of samples. A strong positive correlation was determined between HLA-DRA and HLA-DQA1 levels in tumor tissues (r = 0.7298; P = 0.0003). CONCLUSION: The results reported here along with future studies can be useful to understand the interplay between immune system and GC, therefore, may be helpful to design an effective immune-based therapy.

Gene association analysis to determine the causal relationship between immune cells and juvenile idiopathic arthritis.

BACKGROUND: Juvenile idiopathic arthritis (JIA) is a type of chronic childhood arthritis with complex pathogenesis. Immunological studies have shown that JIA is an acquired self-inflammatory disease, involving a variety of immune cells, and it is also affected by genetic and environmental susceptibility. However, the precise causative relationship between the phenotype of immune cells and JIA remains unclear to date. The objective of our study is to approach this inquiry from a genetic perspective, employing a method of genetic association analysis to ascertain the causal relationship between immune phenotypes and the onset of JIA. METHODS: In this study, a two-sample Mendelian randomization (MR) analysis was used to select single nucleotide polymorphisms (SNPs) significantly associated with immune cells as instrumental variables to analyze the bidirectional causal relationship between 731 immune cells and JIA. There were four types of immune features (median fluorescence intensity (MFI), relative cellular (RC), absolute cellular (AC), and morphological parameters (MP)). Finally, the heterogeneity and horizontal reproducibility of the results were verified by sensitivity analysis, which ensured more robust results. RESULTS: We found that CD3 on CM CD8br was causally associated with JIA at the level of 0.05 significant difference (95% CI = 0.630 ~ 0.847, P = 3.33 × 10-5, PFDR = 0.024). At the significance level of 0.20, two immunophenotypes were causally associated with JIA, namely: HLA DR on CD14+ CD16- monocyte (95% CI = 0.633 ~ 0.884, P = 6.83 × 10-4, PFDR = 0.16) and HLA DR on CD14+ monocyte (95% CI = 0.627 ~ 0.882, P = 6.9 × 10-4, PFDR = 0.16). CONCLUSION: Our study assessed the causal effect of immune cells on JIA from a genetic perspective. These findings emphasize the complex and important role of immune cells in the pathogenesis of JIA and lay a foundation for further study of the pathogenesis of JIA.

Causal relationship between circulating immune cells and the risk of Alzheimer's disease: A Mendelian randomization study.

BACKGROUND: Increasing evidence has shown a link between immune cells and Alzheimer's disease (AD). Comprehensive two-sample Mendelian randomization (MR) analysis was performed to determine the causal association between 731 immune cell signatures and AD in this study. METHODS: We extracted genetic variants of 731 immune cell traits and AD from the publicly available GWAS dataset. The immune features included median fluorescence intensity (MFI), relative cellular (RC), absolute cellular (AC) and morphological parameters (MP). The inverse variance weighted (IVW) method was the main MR analysis method, and sensitivity analyses were used to validate the robustness, heterogeneity and horizontal pleiotropy of the results. RESULTS: After FDR adjustment, seven immune phenotypes were found to be associated significantly with AD risk: HLA DR on CD33-HLA DR+ (OR = 0.938, PFDR = 0.001), Secreting Treg %CD4 (OR = 0.972, PFDR = 0.021), HLA DR+T cell AC (OR = 0.928, PFDR = 0.041), Activated & resting Treg % CD4 Treg (OR = 1.031, PFDR = 0.002), CD33 on CD33dim HLA DR+CD11b+ (OR = 1.025, PFDR = 0.025), CD33 on CD14+monocyte (OR = 1.026, PFDR = 0.027) and CD33 on CD66b++myeloid cell (OR = 1.027, PFDR = 0.036). CONCLUSIONS: These findings demonstrated seven immune phenotypes were significantly associated with AD risk. This may provide researchers with a new perspective in exploring the biological mechanisms of AD and may lead to the exploration of earlier treatment.

Identification of Antibodies to DQß:DRα Interisotypic Heterodimers in Human Sera.

BACKGROUND: HLA class II antigens, DR, DQ, and DP, comprised an α and ß chains, which typically combine, within the same isotype, to form the major histocompatibility complex:peptide complex. Interisotypic pairing is not commonly observed. Although reports of DQß:DRα heterodimers exist, the pairing was reported to be unstable and, therefore, not studied to any extent. METHODS: DQß:DRα single antigens were produced through transfectant cell lines and used to identify and characterize positive reactive human sera by a multiplex bead-based assay. RESULTS: Stable DQß:DRα transfectants were constructed. Cell surface staining with class II-specific monoclonal antibodies revealed that some DQB1 alleles appear to be more efficient in expressing DQß:DRα heterodimers. Interestingly, alleles within the same serological group varied in their efficiency of forming dimers on the cell surface. For example, DQß0601:DRα had the highest transfection and cell membrane expression efficiency among 16 common DQB1 alleles tested. In contrast, DQß0603:DRα-positive transfectants demonstrated minimal surface expression. Assembly of DQß0601:DRα was not affected by the presence of a DQα chain. DQß0601:DRα and DQß0603:DRα single-antigen beads were used to screen human sera. Positive sera were identified that reacted to the unique epitopes of DQß0601:DRα protein on the cell surface of the transfectants. CONCLUSIONS: Our studies have demonstrated that unique DQß:DRα heterodimers can be formed and are stably expressed on the cell surface. Such antigenic combinations, presented on single-antigen beads, demonstrated that patient sera can react with such heterodimers. Investigations on the potential clinical roles of antibodies against such interisotypic heterodimers are now possible.

Human leucocyte antigens and Japanese patients with polymyalgia rheumatica: the protective effect of DRB1*09:01.

OBJECTIVE: The hallmarks of the chronic inflammatory disease polymyalgia rheumatica (PMR) include pain, and morning stiffness in areas of the neck, shoulder and pelvic girdle. The human leucocyte antigen (HLA) gene was reported to be an important risk factor for PMR, but it has not been analysed precisely, especially in populations other than Europeans. METHODS: Genotyping of DRB1 and DQB1 was performed in Japanese PMR patients (n=270) and controls (n=413). Associations between allele carrier and genotype frequencies were determined for PMR. RESULTS: DRB1*04:05 was associated with a predisposition to PMR (p=0.0006, Pc=0.0193, OR 1.85, 95% CI 1.31 to 2.62). DRB1*09:01 was associated with protection against PMR (p=1.46×10-5, Pc=0.0004, OR 0.40, 95% CI 0.26 to 0.61). A shared epitope (SE) associated with PMR (p=3.07×10-6, OR 2.11, 95% CI 1.54 to 2.88). DQB1*03:03 (p=0.0010, Pc=0.0140, OR 0.52, 95% CI 0.35 to 0.77) was associated with protection against PMR and DQB1*04:01 (p=0.0009, Pc=0.0140, OR 1.82, 95% CI 1.28 to 2.58) was associated with predisposition to PMR. A gene dosage effect was observed for DRB1*09:01 and DQB1*03:03, but not for DRB1*04:05, SE or DQB1*04:01. Haplotype and logistic regression analyses suggested a protective effect for DRB1*09:01. CONCLUSION: This study is the first to demonstrate predisposing associations of DRB1*04:05, SE, and DQB1*04:01, and protective associations of DRB1*09:01 and DQB1*03:03 with PMR in Japanese patients. Our data indicate HLA has predisposing and protective effects on the pathogenesis of PMR.

Comprehensive transcriptomic analyses identify the immunosuppressive effects of LLDT-8 in ART-treated SIV-infected rhesus macaques.

BACKGROUND: Chronic immune activation plays a significant role in the pathogenesis and disease progression of human immunodeficiency virus (HIV), and the existing interventions to address this issue are limited. In a phase II clinical trial, (5R)-5-hydroxytriptolide (LLDT-8) demonstrated promising potential in enhancing CD4+ T cell recovery. However, the therapeutical effects of LLDT-8 remained to be systemic explored. METHODS: To assess the treatment effects of LLDT-8, we conducted flow cytometry and RNA-seq analyses on eight Chinese rhesus monkeys infected with simian immunodeficiency virus (SIV). Additionally, we performed comprehensive transcriptomic analyses, including cross-sectional and longitudinal differentially expressed gene (DEG) analysis, gene set enrichment analysis (GSEA), weighted gene co-expression network analysis (WGCNA), and deconvolution analysis using peripheral blood mononuclear cell (PBMC) samples from 14-time points. These findings were further validated with RNA-seq analysis on patients who received LLDT-8 treatment, along with in vitro cellular experiments using human PBMCs. RESULTS: Flow cytometry analysis revealed that LLDT-8 treatment significantly reduced the percentage of HLA-DR+CD38+CD8+ T cells in SIV-infected rhesus monkeys (P < 0.001). The cross-sectional and longitudinal analysis identified 2531 and 1809 DEGs, respectively. GSEA analysis indicated that LLDT-8 treatment led to significant downregulation of proliferation-related pathways, such as E2F targets, G2M checkpoint, and mitotic spindle pathways. WGCNA analysis identified two modules and 202 hub genes associated with CD8 activation levels. Deconvolution analysis showed a significant decrease in the proportion of CD8+ T cells and activated CD4+ T cells during LLDT-8 treatment. Gene ontology results demonstrated that the common DEGs between LLDT-8-treated patients and rhesus monkeys were primarily enriched in cell activation and cell cycle progression. Furthermore, in vitro cellular experiments validated the consistent impact of LLDT-8 in inhibiting proliferation, activation (HLA-DR and CD38 expression), exhaustion (PD-1 expression), and IFN-γ production in human CD4+ and CD8+ T cells. CONCLUSION: LLDT-8 exhibited notable efficacy in alleviating immune activation in both an in vivo animal model and in vitro human cell experiments. These findings suggest that LLDT-8 may hold potential as a drug for managing systemic immune activation associated with SIV/HIV infection, warranting further prospective clinical exploration.

HLA-DR genetic polymorphisms and hepatitis B virus mutations affect the risk of hepatocellular carcinoma in Han Chinese population.

BACKGROUND: Human leucocyte antigen (HLA)-DR plays a crucial role in the immune response against hepatitis B virus (HBV). We aimed to investigate the associations of HLA-DR single nucleotide polymorphisms (SNPs) with the generation of hepatocellular carcinoma (HCC)-related HBV mutations. The effects of HLA-DR SNPs and their interactions with HBV mutations on HCC risks were also determined. METHODS: Five HLA-DR SNPs (rs3135363, rs9268644, rs35445101, rs24755213, and rs984778) were genotyped in 792 healthy controls, 586 chronic hepatitis B (CHB) patients, 536 liver cirrhosis (LC) patients, and 1500 HCC patients using quantitative PCR. Sanger sequencing was used to identify the HBV mutations. Logistic regression model was performed to evaluate the association of HLA-DR SNPs with HCC risk and the frequencies of HCC-related HBV mutations. RESULTS: The variant genotypes at rs3135363, rs9268644, rs35445101, rs24755213, and rs984778 were associated with decreased HCC risks. In genotype C HBV-infected subjects, variant genotypes of these SNPs were associated with decreased frequencies of HCC-related HBV mutations such as C1653T, T1674C/G, G1719T, T1753A/C, A1762T/G1764A, A1846T, G1896A, G1899A, and preS deletion. AG genotype at rs3135363, CA genotype at rs9268644, and AG genotype at rs24755213 reduced the generation of T1753A/C and G1896A in genotype B HBV-infected subjects, respectively. In addition, the interactions of rs3135363, rs9268644, rs24755213 with C1653T, T1753A/C, A1846T, and G1896A decreased the risks of HCC. CONCLUSIONS: HLA-DR genetic polymorphisms might predispose the host to immunoselection of HCC-related HBV mutations and affect the HCC risks possibly through interacting with HBV mutations.

HLA-DR genotypes in patients with systemic lupus erythematosus in Taiwan.

BACKGROUND: Different human leukocyte antigen (HLA)-DR genotypes have been known to be associated with the risk of development of systemic lupus erythematosus (SLE) in different populations, although Lu et al. have reported previously that no correlation exists between the HLA-DR genotype and disease manifestation in SLE patients in Taiwan. We investigated the effects different HLA-DR genotypes had on SLE incidence in Taiwanese patients as to whether risk alleles were associated with different clinical manifestations, and the effects risk alleles had on the age of disease onset. METHODS: Two hundred thirty-four SLE patients and 346 healthy controls were enrolled. HLA-DR genotyping was performed with the HLA FluoGene DRDQ kit for each subject. Chi-square tests and t tests were performed for statistical analysis. RESULTS: HLA-DR2 was significantly more frequently found in SLE patients than in controls (odds ratio [OR] = 2.05, 95% CI, 1.44-2.92, p < 0.001). Notably, HLA-DR6 appeared to trend toward negative correlation with SLE, whereas HLA-DR8 appeared to trend toward positive correlation. HLA-DR2 patients had an earlier onset of disease as well as a higher prevalence of oral ulcer, avascular necrosis of bone, and renal involvement (lupus nephritis). CONCLUSION: HLA-DR2 was associated with SLE susceptibility in this Taiwanese population as well as lower age of disease onset and more severe clinical manifestations.

Role of HLA alleles polymorphism in systemic lupus erythematosus: A prospective study from North India.

Background: Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder and has complex etiopathogenesis. The most appropriate hypothesis states that genetic susceptibility in the presence of environmental risk factors predisposes to SLE. HLA class II alleles are critical to immune response and are highly polymorphic. Various alleles in HLA-DR and -DQ regions were analyzed in SLE patients and healthy controls to see their role in susceptibility or protection to SLE. Materials and Methods: This was a prospective observational study, in which a total of 100 SLE patients and 100 controls were analyzed. HLA typing was done by polymerase chain reaction (PCR)-sequence-specific oligonucleotide (SSO) method (SSO probe). Results: DRß1*0301 was significantly increased in SLE patients when compared to controls and had the highest odds ratio. Other risk factor alleles found to be increased were DRß1*0701, DQß1*0202, and DQß1*0301, which had a significant positive association with SLE, suggesting their role in susceptibility to SLE. In contrast, DRß1*0401, DRß1*1401, DRß1*1404, DRß1*1501, DQß1*0501, and DQα1*0201 showed statistically significant reduction in SLE patients, while these were much more common in controls, suggesting their protective role. Conclusion: This study is only the second study in patients from North India and it determines the role of DRß1*0301, DRß1*0701, DQß1*0202, and DQß1*0301 alleles as risk factors in SLE patients.

Kynurenine pathway alteration in acute pancreatitis and its role as a biomarker of infected necrosis.

INTRODUCTION: Infected pancreatic necrosis (IPN) is a major cause of mortality in acute pancreatitis (AP). Currently, no specific strategies are available to predict the development of IPN. Earlier we reported that persistent down-regulation of HLA-DR increases risk of developing IPN. Altered kynurenine pathway (KP) metabolites showed poor prognosis in sepsis. Here we evaluated the role of HLA-DR and KP in IPN. METHODS: Patients with ANP and healthy controls were enrolled. Demographic and clinical parameters were recorded. Circulating interleukin (IL)-8, 6, 1ß, 10, Tumor necrosis factor-α were quantified using flowcytometry. Plasma procalcitonin, endotoxin, and KP (tryptophan, kynurenine) concentrations were estimated using ELISA. qRT-PCR was conducted to evaluate mRNA expression of HLA-DR, IL-10, Toll like receptor-4 (TLR-4), and kynurenine-3-monooxygenase (KMO) genes on peripheral blood mononuclear cells. Plasma metabolites were quantified using gas chromatography mass spectrometry (GC-MS/MS). Standard statistical methods were used to compare study groups. Metaboanalyst was used to analyse/visualize the metabolomics data. RESULTS: We recruited 56 patients in Cohort-1 (IPN:26,Non-IPN:30), 78 in Cohort-2 (IPN:57,Non-IPN:21), 26 healthy controls. Increased cytokines, endotoxin, and procalcitonin were observed in patients with IPN compared to Non-IPN. HLA-DR and KMO gene expressions were significantly down-regulated in IPN groups, showed positive correlation with one another but negatively correlated with IL-6 and endotoxin concentrations. Increased IDO and decreased plasma tryptophan were observed in IPN patients. Metabolome analysis showed significant reduction in several essential amino acids including tryptophan in IPN patients. Tryptophan, at a concentration of 9 mg/ml showed an AUC of 91.9 (95%CI 86.5-97.4) in discriminating IPN. CONCLUSION: HLA-DR downregulation and KP alteration are related to IPN. The KP metabolite plasma tryptophan can act as a potential biomarker for IPN.

Association of HLA class II DR/DQ alleles in children and adolescents with rheumatic heart disease from a tertiary care centre in North India.

INTRODUCTION: Rheumatic fever and RHD constitutes an important public health problem in India. The relatively low attack rate of RF, the high concordance rate for RF in monozygotic twins (19%) compared to dizygotic twins (2.5%), and the high familial incidence of RF suggest the involvement of host genetic factors in susceptibility to RF with consequential progression to RHD. OBJECTIVE: To study the association of HLA CLASS II DR/DQ alleles in children and adolescents with RHD from a tertiary care center in North India. METHODS: 30 RHD patients and 30 age and sex-matched controls were included in our study and blood samples for HLA typing were processed through LAB Type™ reverse SSO DNA typing method. The assignment of the HLA typing was based on a comparison with already published HLA gene sequences. RESULTS: The mean age of RHD patients and matched control groups were 12.97 ± 2.95 and 11.93 ± 3.23, respectively. In the cases and control group, males accounted for 63.3% and 50% of the patients respectively. A significant difference was found between the cases and controls for HLA DR∗ 15 (p-value 0.002), HLA DR∗ B4 (p-value 0.045), HLA DR∗ B5 (p-value 0.017), and HLA DQB1∗ 02 (p-value 0.005). CONCLUSION: Our study suggests that HLA class II haplotypes may provide insight into the molecular mechanism of RHD and be a useful tool in predicting the clinical outcome in RF patients, thereby affording new means of intervention or vaccine design. Larger studies are needed to address this in our population.

Differential pairing of transmembrane domain GxxxG dimerization motifs defines two HLA-DR MHC class II conformers.

MHC class II molecules function to present exogenous antigen-derived peptides to CD4 T cells to both drive T cell activation and to provide signals back into the class II antigen-presenting cell. Previous work established the presence of multiple GxxxG dimerization motifs within the transmembrane domains of MHC class II α and ß chains across a wide range of species and revealed a role for differential GxxxG motif pairing in the formation of two discrete mouse class II conformers with distinct functional properties (i.e., M1-and M2-paired I-Ak class II). Biochemical and mutagenesis studies detailed herein extend this model to human class II by identifying an anti-HLA-DR mAb (Tü36) that selectively binds M1-paired HLA-DR molecules. Analysis of the HLA-DR allele reactivity of the Tü36 mAb helped define other HLA-DR residues involved in mAb binding. In silico modeling of both TM domain interactions and whole protein structure is consistent with the outcome of biochemical/mutagenesis studies and provides insight into the possible structural differences between the two HLA-DR conformers. Cholesterol depletion studies indicate a role for cholesterol-rich membrane domains in the formation/maintenance of Tü36 mAb reactive DR molecules. Finally, phylogenetic analysis of the amino acid sequences of Tü36-reactive HLA-DR ß chains reveals a unique pattern of both Tü36 mAb reactivity and key amino acid polymorphisms. In total, these studies bring the paradigm M1/M2-paired MHC class II molecules to the human HLA-DR molecule and suggest that the functional differences between these conformers defined in mouse class II extend to the human immune system.

Immune Profiling Panel Gene Set Identifies Critically Ill Patients With Low Monocyte Human Leukocyte Antigen-DR Expression: Preliminary Results From the REAnimation Low Immune Status Marker (REALISM) Study.

OBJECTIVES: There is a crucial unmet need for biomarker-guided diagnostic and prognostic enrichment in clinical trials evaluating immune modulating therapies in critically ill patients. Low monocyte expression of human leukocyte antigen-DR (mHLA-DR), considered as a reference surrogate to identify immunosuppressed patients, has been proposed for patient stratification in immunostimulation approaches. However, its widespread use in clinic has been somewhat hampered by technical constraints inherent to flow cytometry technology. The objective of the present study was to evaluate the ability of a prototype multiplex polymerase chain reaction tool (immune profiling panel [IPP]) to identify immunosuppressed ICU patients characterized by a low mHLA-DR expression. DESIGN: Retrospective observational cohort study. SETTING: Adult ICU in a University Hospital, Lyon, France. PATIENTS: Critically ill patients with various etiologies enrolled in the REAnimation Low Immune Status Marker study (NCT02638779). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: mHLA-DR and IPP data were obtained from 1,731 blood samples collected from critically ill patients with various etiologies and healthy volunteers. A partial least square regression model combining the expression levels of IPP markers was trained and used for the identification of samples from patients presenting with evidence of immunosuppression, defined here as mHLADR less than 8,000 antibodies bound per cell (AB/C). The IPP gene set had an area under the receiver operating characteristic curve (AUC) of 0.86 (95% CI 0.83-0.89) for the identification of immunosuppressed patients. In addition, when applied to the 123 patients still in the ICU at days 5-7 after admission, IPP similarly enriched the number of patients with ICU-acquired infections in the immunosuppressed group (26%), in comparison with low mHLA-DR (22%). CONCLUSIONS: This study reports on the potential of the IPP gene set to identify ICU patients presenting with mHLA-DR less than 8,000 AB/C. Upon further optimization and validation, this molecular tool may help in the stratification of patients that could benefit from immunostimulation in the context of personalized medicine.

Primitive haematopoiesis in the human placenta gives rise to macrophages with epigenetically silenced HLA-DR.

The earliest macrophages are generated during embryonic development from erythro-myeloid progenitors (EMPs) via primitive haematopoiesis. Although this process is thought to be spatially restricted to the yolk sac in the mouse, in humans, it remains poorly understood. Human foetal placental macrophages, or Hofbauer cells (HBC), arise during the primitive haematopoietic wave ~18 days post conception and lack expression of human leukocyte antigen (HLA) class II. Here, we identify a population of placental erythro-myeloid progenitors (PEMPs) in the early human placenta that have conserved features of primitive yolk sac EMPs, including the lack of HLF expression. Using in vitro culture experiments we demonstrate that PEMP generate HBC-like cells lacking HLA-DR expression. We find the absence of HLA-DR in primitive macrophages is mediated via epigenetic silencing of class II transactivator, CIITA, the master regulator of HLA class II gene expression. These findings establish the human placenta as an additional site of primitive haematopoiesis.

Prospective flow cytometry analysis of leucocyte subsets in critically ill patients who develop sepsis: a pilot study.

PURPOSE: Sepsis in critically ill patients with injury bears a high morbidity and mortality. Extensive phenotypic monitoring of leucocyte subsets in critically ill patients at ICU admission and during sepsis development is still scarce. The main objective of this study was to identify early changes in leukocyte phenotype which would correlate with later development of sepsis. METHODS: Patients who were admitted in a tertiary ICU for organ support after severe injury (elective cardiac surgery, trauma, necessity of prolonged ventilation or stroke) were sampled on admission (T1) and 48-72 h later (T2) for phenotyping of leukocyte subsets by flow cytometry and cytokines measurements. Those who developed secondary sepsis or septic shock were sampled again on the day of sepsis diagnosis (Tx). RESULTS: Ninety-nine patients were included in the final analysis. Nineteen (19.2%) patients developed secondary sepsis or septic shock. They presented significantly higher absolute monocyte counts and CRP at T1 compared to non-septic patients (1030/µl versus 550/µl, p = 0.013 and 5.1 mg/ml versus 2.5 mg/ml, p = 0.046, respectively). They also presented elevated levels of monocytes with low expression of L-selectin (CD62Lneg monocytes) (OR[95%CI] 4.5 (1.4-14.5), p = 0.01) and higher SOFA score (p < 0.0001) at T1 and low mHLA-DR at T2 (OR[95%CI] 0.003 (0.00-0.17), p = 0.049). Stepwise logistic regression analysis showed that both monocyte markers and high SOFA score (> 8) were independently associated with nosocomial sepsis occurrence. No other leucocyte count or surface marker nor any cytokine measurement correlated with sepsis occurrence. CONCLUSION: Monocyte counts and change of phenotype are associated with secondary sepsis occurrence in critically ill patients with injury.

Significance of HLA in the development of Graves' orbitopathy.

Graves' disease (GD), similarly to most autoimmune disease, is triggered by environmental factors in genetically predisposed individuals. Particular HLA alleles increase or decrease GD risk. No such correlation was demonstrated for Graves' orbitopathy (GO) in Caucasian population. HLA-A, -B, -C, -DQB1 and -DRB1 genotyping was performed using a high-resolution method in a total number of 2378 persons including 70 patients with GO, 91 patients with non-GO GD and 2217 healthy controls to compare allele frequencies between GO, non-GO and controls. Significant associations between GO and HLA profile were demonstrated, with HLA-A*01:01, -A*32:01, -B*37:01, -B*39:01, -B*42:01, -C*08:02, C*03:02, DRB1*03:01, DRB1*14:01 and DQB1*02:01 being genetic markers of increased risk of GO, and HLA-C*04:01, -C*03:04, -C*07:02 and -DRB1*15:02 being protective alleles. Moreover, correlations between HLA alleles and increased or decreased risk of non-GO GD, but with no impact on risk of GO development, were revealed. Identification of these groups of GO-related and GO-protective alleles, as well as the alleles strongly related to non-GO GD, constitutes an important step in a development of personalized medicine, with individual risk assessment and patient-tailored treatment.

CD34 negative HLA-DR negative acute myeloid leukaemia: A higher association with NPM1 and FLT3-ITD mutations.

INTRODUCTION: CD34 and HLA-DR negativity is often used as a characteristic immunophenotypic feature of acute promyelocytic leukaemia (APL) that differentiates APL from other subtypes of acute myeloid leukaemia (AML). However, other subtypes of AML, without expression of CD34 and HLA-DR antigens, have also been reported. METHODS: We analysed the HLA-DR negative de novo non-APL AML cases by dividing HLA-DR negative non-APL group into 2 sub-groups based on CD34 expression and compared the characteristics of CD34 negative HLA-DR negative with CD34 positive HLA-DR negative non-APL AML cases with respect to morphologic, immunophenotypic, molecular and clinical parameters. RESULTS: There were 70 cases (8.54%) which were CD34 negative HLA-DR negative and 52 cases (6.34%) were CD34 positive HLA-DR negative. The median age at diagnosis was higher in CD34 negative HLA-DR negative AML than in CD34 positive HLA-DR negative AML group (38 years vs. 12 years, p < 0.001). DIC rate was higher in CD34 negative HLA-DR negative group than the other group (p < 0.001). Median total leucocyte count was higher with higher blast count in peripheral blood and bone marrow in CD34 negative HLA-DR negative AML cases than the other group (p < 0.05). CD34 negative HLA-DR negative AML was more associated with normal karyotype (96.2% vs. 38.5%; p < 0.001), NPM1 mutation (67.8% vs. 8.3%; p < 0.001) and FLT-ITD mutation (37.3% vs. 13.9%; p < 0.05). In CD34 negative HLA-DR negative group, 16 cases had co-occurrence of NPM1 and FLT3-ITD mutations, whereas no case of CD34 positive HLA-DR negative group had such dual mutation positivity. There was poor median overall survival [3.8 months (95%CI: 2.3-7.8 months) vs. 20.4 months (95% CI: 12.8-25.7 months); p = 0.0148] in CD34 positive HLA-DR negative AML than CD34 negative HLA-DR negative AML cases. CONCLUSION: We found that the CD34 negative HLADR negative non APL AML is highly associated with NPM1 and FLT3-ITD mutation, older age at diagnosis, DIC, higher total leucocyte count, higher blast counts and normal karyotype in comparison to CD34 positive HLA-DR negative AML group. Co-occurrence of NPM1 and FLT3-ITD mutation was also exclusively seen in CD34 negative HLA-DR negative group. There was poor overall survival in CD34 positive HLA-DR negative AML than CD34 negative HLA-DR negative AML cases.

HLA class I and class II antigens in sarcoidosis.

BACKGROUND: Sarcoidosis is a multisystem granulomatous disorder. Its exact cause is unknown, but it is believed that an external agent may cause the characteristic immune reaction in genetically susceptible individuals. There is therefore general recognition that genetic vulnerability to sarcoidosis is one of the potential risk factors. HLA is encoded by genes in the major histocompatibility complex on chromosome 6. These surface cells are important in presentation of antigen and play a key part in the body's immune response to external antigens. Various HLA subtypes are more common in people with sarcoidosis than in those without. Variances in vulnerability, presentation, progression and prognosis have been related to different HLA phenotypes. HLA genes offer information into the factors driving sarcoidosis and prognosticating tools. However, in Africa, including South Africa (SA), there are no data on HLA types in relation to sarcoidosis. OBJECTIVES: To determine HLA class I and II associations in SA sarcoidosis patients. METHODS: Phenotype frequencies of HLA-A, B and C and DQB1 and DRB1 were calculated for 51 consecutive patients with biopsy-proven sarcoidosis attending the respiratory clinic at Charlotte Maxeke Johannesburg Academic Hospital and 63 controls, who were potential organ donors. The frequencies of the tested HLA loci were determined by direct counting. The significance of the associations between the various loci tested for and the presence or absence of sarcoidosis was estimated from 2 × 2 tables using the χ2 test. RESULTS: Of the 51 patients, 70.6% were female. The mean age was 44.6 years. Analysis of HLA class I and class II phenotypes in sarcoidosis patients revealed a significant association with HLA-B15, C4, C7, C12, C15, C16, C17, DQ3, DR8 and DR11. In addition, a significant negative (protective) association with HLA A9, A28, B12, B17 and DR2 was observed. CONCLUSION: This HLA study in SA patients suggests that genetic factors play a role in the causation of sarcoidosis. Some HLA subtypes have a significant association with sarcoidosis in SA patients, while other subtypes may be protective. The study supported the association of HLA antigens with sarcoidosis and implies that there is a genetic predisposition to sarcoidosis in the SA population.