Major Histocompatibility Complex Class I-related Research Articles

MR1 gene and protein expression are enhanced by inhibition of the extracellular signal-regulated kinase ERK.

The MHC class I-related molecule MR1 is ubiquitously expressed, is highly conserved among mammals, and presents bacterial and endogenous antigens in tumor cells. These features indicate that tumor-specific T cells restricted to MR1 may represent ideal candidates for novel cancer-directed T-cell immunotherapy. The very low expression of the MR1 protein at the cell surface is a potential challenge limiting the possible use of MR1-directed immunotherapies. To overcome this challenge, it is important that understanding of the mechanisms regulating MR1 expression is increased, as little is known about this currently. This study identified ERK1/2 as negative regulators of the MR1 gene and protein expression. Inhibition of ERK1/2 in tumor cells or treatment of BRAF-mutant tumor cells with drugs specific for mutated BRAF increased MR1 protein expression and recognition by tumor-reactive and MR1-restricted T cells. The ERK1/2 inhibition of MR1 was mediated by the ELF1 transcription factor, which was required for MR1 gene expression. The effects of ERK1/2 inhibition also occurred in cancer cell lines of different tissue origins, cancer cell lines resistant to drugs that inhibit mutated BRAF, and primary cancer cells, making them potential targets of specific T cells. In contrast to tumor cells, the recognition of healthy cells was very poor or absent after ERK1/2 inhibition. These findings suggest a pharmaceutical approach to increase MR1 protein expression in tumor cells and the subsequent activation of MR1-restricted T cells, and they have potential therapeutic implications.

Abstract 1590: The role of mucosal associated invariant T (MAIT) cells in pancreatic cancer liver metastasis

Abstract Pancreatic cancer liver metastasis (PCLM) is present in 50% of patients diagnosed with pancreatic ductal adenocarcinoma (PDAC) and leads to a median survival of <6 months. Here, we sought to identify urgently needed therapeutic options for treating PCLM by targeting mucosal associated invariant T (MAIT) cells, an invariant T cell restricted to MHCI related protein (MR1). MAIT cells are a unique subset of T cells that are classified as “protumor” MAIT17 and “antitumor” MAIT1 cells. We hypothesize that the PCLM tumor microenvironment (TME) induces direct MAIT cell activation via MR1 which primes MAIT cells towards a “protumor” phenotype. Using publicly available TCGA data, we found that PDAC tumors were enriched for MR1 gene expression compared to healthy tissue and patients with lower tumor MR1 expression had better overall survival. Next, immunostaining of MR1 on tumor samples from primary PDAC and PCLM revealed that that MR1 protein expression is highly enriched in the TME and localized to the surface of tumor cells. This suggests that MAIT cells in the PCLM TME are being activated directly via an MR1 dependent pathway. Next, we performed hemi-spleen injection of mouse pancreatic cancer cells into WT and MR1 KO (lacks MAIT cells) mice to model PCLM. Interestingly, MAIT cells in the WT PCLM mice were shifted towards the “pro-tumor” MAIT17 phenotype. Furthermore, the lack of MAIT cells in MR1 KO mice significantly reduced tumor burden compared to WT mice. Lastly, we found that MR1 KO mice had a reduction in exhausted NK and NKT cells which likely promoted anti-tumor immunity. Overall, we find that the PCLM TME promotes “pro-tumor” MAIT17 cells via MR1 mediated activation and these MAIT17 cells inhibit anti-tumor cells such as NK and NKT cells. This work identifies targeting MAIT cells as a novel immunotherapy approach for PCLM. Citation Format: Jugmohit Toor, Peter Dimitrion, Rachel Krevh, Kalpana Subedi, Bobby Zuniga, Jie Wang, Li Zhou, Qing-Sheng Mi. The role of mucosal associated invariant T (MAIT) cells in pancreatic cancer liver metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1590.

Control of the temporal development of Alzheimer’s disease pathology by the MR1/MAIT cell axis

BackgroundNeuroinflammation is an important feature of Alzheimer’s disease (AD). Understanding which aspects of the immune system are important in AD may lead to new therapeutic approaches. We study the major histocompatibility complex class I-related immune molecule, MR1, which is recognized by an innate-like T cell population called mucosal-associated invariant T (MAIT) cells.MethodsHaving found that MR1 gene expression is elevated in the brain tissue of AD patients by mining the Agora database, we sought to examine the role of the MR1/MAIT cell axis in AD pathology. Brain tissue from AD patients and the 5XFAD mouse model of AD were used to analyze MR1 expression through qPCR, immunofluorescence, and flow cytometry. Furthermore, mice deficient in MR1 and MAIT cells were crossed with the 5XFAD mice to produce a model to study how the loss of this innate immune axis alters AD progression. Moreover, 5XFAD mice were also used to study brain-resident MAIT cells over time.ResultsIn tissue samples from AD patients and 5XFAD mice, MR1 expression was substantially elevated in the microglia surrounding plaques vs. those that are further away (human AD: P < 0.05; 5XFAD: P < 0.001). In 5XFAD mice lacking the MR1/MAIT cell axis, the development of amyloid-beta plaque pathology occurred at a significantly slower rate than in those mice with MR1 and MAIT cells. Furthermore, in brain tissue from 5XFAD mice, there was a temporal increase in MAIT cell numbers (P < 0.01) and their activation state, the latter determined by detecting an upregulation of both CD69 (P < 0.05) and the interleukin-2 receptor alpha chain (P < 0.05) via flow cytometry.ConclusionsTogether, these data reveal a previously unknown role for the MR1/MAIT cell innate immune axis in AD pathology and its potential utility as a novel therapeutic target.

The case of paroxysmal kinesigenic dyskinesia: a long way from a symptom to the diagnosis

Paroxysmal kinesigenic dyskinesia belongs to the group of primary dyskinesias, which also includes paroxysmal non-kinesigenic dyskinesia and exercise-induced paroxysmal dyskinesia. Due to the rarity of this disease group, as well as to the existence of a wide spectrum of disorders associated with transient movement abnormalities, the diagnosis is often difficult. A thorough analysis of clinical presentation, objective registration of paroxysmal events (video-electroencephalography monitoring) is helpful in the diagnosis. The most common causes of paroxysmal kinesigenic dyskinesia are mutations in the PRRT2 gene, while paroxysmal non-kinesigenic dyskinesia is caused by the MR1 gene mutations.The paper describes a clinical case of a 13 year old patient with acute, movement-associated, shortterm dystonic, choreic and ballistic hyperkinesis attacks. The patient had been treated with the diagnosis of epilepsy, tics, and dystonia for a long time without any effect. During diagnostic workup, a mutation in the PRRT2 gene intron was identified by a new generation sequencing of gene panel. Despite of this mutation has not been previously described, taking into account the type of Informed consent statement hyperkinesis attacks, association of their onset to movements, as well as the data of instrumental assessments, the diagnosis of paroxysmal kinesi-genic dyskinesia was made. Treatment with carbamazepine was successful with complete control over hyperkinesis.The diagnosis of paroxysmal dyskinesias remains based on the analysis of clinical picture and the trigger type. Molecular genetic diagnostics, with consideration of the most frequent causal mutations related to these conditions, can minimize both time and financial costs.

MR1 overexpression correlates with poor clinical prognosis in glioma patients.

BackgroundGlioblastoma is the most common adult primary brain tumor with near-universal fatality. Major histocompatibility complex (MHC) class I molecules are important mediators of CD8 activation and can be downregulated by cancer cells to escape immune surveillance. MR1 is a nonclassical MHC-I-like molecule responsible for the activation of a subset of T cells. Although high levels of MR1 expression should enhance cancer cell recognition, various tumors demonstrate MR1 overexpression with unknown implications. Here, we study the role of MR1 in glioma.MethodsUsing multi-omics data from the Cancer Genome Atlas (TCGA), we studied MR1 expression patterns and its impact on survival for various solid tumors. In glioma specifically, we validated MR1 expression by histology, elucidate transcriptomic profiles of MR1 high versus low gliomas. To understand MR1 expression, we analyzed the methylation status of the MR1 gene and MR1 gene-related transcription factor (TF) expression.Results MR1 is overexpressed in all grades of glioma and many other solid cancers. However, only in glioma, MR1 overexpression correlated with poor overall survival and demonstrated global dysregulation of many immune-related genes in an MR1-dependent manner. MR1 overexpression correlated with decreased MR1 gene methylation and upregulation of predicted MR1 promoter binding TFs, implying MR1 gene methylation might regulate MR1 expression in glioma.ConclusionsOur in silico analysis shows that MR1 expression is a predictor of clinical outcome in glioma patients and is potentially regulated at the epigenetic level, resulting in immune-related genes dysregulation. These findings need to be validated using independent in vitro and in vivo functional studies.

Antigen specificities and functional properties of MR1-restricted T cells

MR1 is an MHC class I-like molecule with unique structural and biological features that make it an important member among the molecules involved in antigen presentation to T cells. Distinctive features include ubiquitous expression of the MR1 gene and its monomorphism. Another relevant property is that the MR1 protein appears at very low levels on the plasma membrane and its surface expression is regulated by antigen binding. Finally, the nature of presented antigens differs from those that bind other presenting molecules and includes small metabolites of microbial and self-origin, small drugs and tumor-associated antigens. This opinion paper describes in detail some of those features and discusses recent literature in the field.

A human immune system sans MAIT cells

Immunodeficiency Mucosal-associated invariant T (MAIT) cells represent ∼5% of circulating human T cells, reside in high frequency in mucosal tissues, and provide enhanced immunity against bacterial and viral infections. Howson et al. set out to determine the genetic basis of immunodeficiency in a patient with persistent tattoo-associated human papilloma virus–positive warts. The gene MR1 encodes a major histocompatibility complex–like molecule that presents bacteria-derived riboflavin metabolites to MAIT cells. Whole-exome sequencing led the researchers to identify a rare point mutation in both copies of the MR1 gene. By solving the structure of the mutant MR1 protein, they demonstrated that the mutation disrupted the ligand-binding domain of MR1. Consistent with this finding, the patient lacked circulating MAIT cells. Sci. Immunol. 5 , eabc9492 (2020).

Molecular cloning and characterization of the pig MHC class Ⅰ-related MR1 gene

Major histocompatibility complex (MHC) class Ⅰ-related protein 1 (MR1), the most highly conserved MHC class Ⅰ molecule among mammals, is the restricting molecule for mucosal-associated invariant T (MAIT) cells. MAIT cells, a novel subset of T cells, play important roles in modulating the immune responses to infectious and non-infectious diseases, and recognize antigens in the context of MR1. MR1 has been identified in many species, including human, mouse, sheep, and cow. Here, we cloned and characterized pig (Sus scrofa) MR1 (pMR1) transcripts, including five unique splice variants, from pig peripheral blood mononuclear cell cDNA. We also examined the tissue distribution of pMR1 and confirmed reactivity of pMR1 using a MR1 specific monoclonal antibody 26.5, demonstrating that the pMR1 gene was expressed in all tested tissues. Finally, we predicted the pMR1 3D structure and analyzed the docking mode of the MR1-5-OP-RU complex, finding that the docking mode of pMR1 with 5-OP-RU is similar to human MR1 docking. Collectively, this description of pMR1 adds to our understanding of the evolution of MHC molecules, and provides a theoretical basis for the subsequent study of pig MAIT cells.

Risk Factor Genes in Patients with Dystonia: A Comprehensive Review.

BackgroundDystonia is a movement disorder with high heterogeneity regarding phenotypic appearance and etiology that occurs in both sporadic and familial forms. The etiology of the disease remains unknown. However, there is increasing evidence suggesting that a small number of gene alterations may lead to dystonia. Although pathogenic variants to the familial type of dystonia have been extensively reviewed and discussed, relatively little is known about the contribution of single-nucleotide polymorphisms (SNPs) to dystonia. This review focuses on the potential role of SNPs and other variants in dystonia susceptibility.MethodsWe searched the PubMed database for peer-reviewed articles published in English, from its inception through January 2018, that concerned human studies of dystonia and genetic variants. The following search terms were included: “dystonia” in combination with the following terms: 1) “polymorphisms” and 2) “SNPs” as free words.ResultsA total of 43 published studies regarding TOR1A, BDNF, DRD5, APOE, ARSG, NALC, OR4X2, COL4A1, TH, DDC, DBH, MAO, COMT, DAT, GCH1, PRKRA, MR-1, SGCE, ATP1A3, TAF1, THAP1, GNAL, DRD2, HLA-DRB, CBS, MTHFR, and MS genes, were included in the current review.DiscussionTo date, a few variants, which are possibly involved in several molecular pathways, have been related to dystonia. Large cohort studies are needed to determine robust associations between variants and dystonia with adjustment for other potential cofounders, in order to elucidate the pathogenic mechanisms of dystonia and the net effect of the genes.

Mammalian CD1 and MR1 genes.

All higher vertebrates share the fundamental components of the adaptive immune system: the B cell receptor, the T cell receptor, and classical MHC proteins. At a more detailed level, their immune systems vary considerably, especially with respect to the non-polymorphic MHC class I-like proteins. In mammals, the CD1 family of lipid-presenting proteins is encoded by clusters of genes of widely divergent sizes and compositions. Another MHC class I-like protein, MR1, is typically encoded by a single gene that is highly conserved among species. Based on mammalian genomes and the available data on cellular expression profiles and protein structure, we review MR1 genes and families of CD1 genes in modern mammals from a genetic and functional perspective. Understanding the CD1 and MR1 systems across animal species provides insights into the specialized functions of the five types of CD1 proteins and facilitates careful consideration of animal models for human diseases in which immune responses to lipids and bacterial metabolites play a role.

MR1 discovery.

The moment of MR1 discovery is described. The MR1 gene is the first and the last reported human MHC-related gene intentionally isolated from the human genome composed of three billion base pairs. Evolutionary considerations formed the basis of its isolation. Some details surrounding the moment and some retrospective descriptions with various kinds of encounters are also included.

Mutation Analysis of MR-1, SLC2A1, and CLCN1 in 28 PRRT2-negative Paroxysmal Kinesigenic Dyskinesia Patients.

Background:Paroxysmal kinesigenic dyskinesia (PKD) is the most common subtype of paroxysmal dyskinesias and is caused by mutations in PRRT2 gene. The majority of familial PKD was identified to harbor PRRT2 mutations. However, over two-third of sporadic PKD patients did not carry any PRRT2 mutation, suggesting an existence of additional genetic mutations or possible misdiagnosis due to clinical overlap.Methods:A cohort of 28 Chinese patients clinically diagnosed with sporadic PKD and excluded PRRT2 mutations were recruited. Clinical features were evaluated, and all subjects were screened for MR-1, SLC2A1, and CLCN1 genes, which are the causative genes of paroxysmal nonkinesigenic dyskinesia (PNKD), paroxysmal exertion-induced dyskinesia, and myotonia congenita (MC), respectively. In addition, 200 genetically matched healthy individuals were recruited as controls.Results:A total of 16 genetic variants including 4 in MR-1 gene, 8 in SLC2A1 gene, and 4 in CLCN1 gene were detected. Among them, SLC2A1 c.363G>A mutation was detected in one case, and CLCN1 c.1205C>T mutation was detected in other two cases. Neither of them was found in 200 controls as well as 1000 Genomes database and ExAC database. Both mutations were predicted to be pathogenic by SIFT and PolyPhen2. The SLC2A1 c.363G>A mutation was novel.Conclusions:The phenotypic overlap may lead to the difficulty in distinguishing PKD from PNKD and MC. For those PRRT2- negative PKD cases, screening of SLC2A1 and CLCN1 genes are useful in confirming the diagnosis.

Expression and clinical value of major histocompatibility complex class-I related chain A molecule in serum of patients with renal tumor

Objective To explore the expression and clinical value of major histocompatibility complex class-I related chain A (sMICA) molecule in serum of patients with renal tumor. Methods From March 2013 to July 2013, 60 patients with renal tumor, including 37 male patients and 23 female patients were enrolled in this study as experimental group. The mean age was 46 years (range 34-76 years). The pathological diagnosis included renal cell carcinoma in 48 cases and renal angiomyolipoma in 12 cases. The stage classification included T1 stage in 20 cases, T2 stage in 14 cases, T3 stage in 10 cases and T4 stage in 4 cases. Lymphatic metastases were found in 11 cases and metastases in other organs were found in 4 cases. Another 20 healthy volunteers were enrolled as control group, including 10 male and 10 female. The mean age was 31 years (range 24-50 years). The ELISA method was used to detect the soluble MICA′s (sMICA) level in serum. And the results were compared with tumor′s malice, TNM pathology stages, metastasis. In 15 cases with renal cell carcinoma, the expression of MICA molecule in tumor masses and paraneoplastic masses was measured by immunohistochemical (IHC) method. The quantitative expression of MICA-mRNA was detected by RT-PCR in 9 tumor masses and 3 paraneoplastic masses. Results The level of sMICA in renal malignant tumor group was (348.5±32.5) pg/ml, while the sMICA′s level in benign renal tumor groups was (289.3±30.4) pg/ml and that in the control group was (168.4±43.2) pg/ml. The level of sMICA in malignant group is statistically higher than that in benign group and control group (P 0.05). Significant difference in the sMICA level could also be observed between patients with other organ metastasis (373.4±45.4) pg/ml and those without metastasis (346.4±31.5) pg/ml (P<0.05). The IHC results revealed that high expression of MICA molecule in tumor cell. However , this oppsite result was demonstrated in cells located in paraneoplastic tissues. In the results of RT-PCR, the MICA-mRNA level (2.03) in tumor masses was significantly higher than that in pareneoplastic masses (0.77) (P<0.05). Conclusions MICA highly expressed in renal tumor, and its expression correlates with tumor′s malice, TNM pathologic stages, and metastasis. Key words: Renal tumor; Major histocompatibility complex class-I related chain A; Natural killer cell

Identification and characterization of Raoutella ornithilolytica and determination of its herbicide 2,2-dichloropropionate (2,2-DCP) degradation potential

Aims: The goal of the study is to isolate new bacteria species which are capable to utilizing 2,2-dichlropropionic acid (22-DCP) as a sole carbon source from the wastewater sample that was taken from Tioman Island off the coast of Malaysia. Methodology and results: Genomic DNA from unknown bacterial strain (MR1) was extracted and PCR amplification was carried out using universal primers, Fd1 (5’-AGA GTT TGA TCC TGGCTC AG-3’) and rP1 (5’-ACG GTC ATA CCT TGT TAC GAC TT-3’) prior to sequencing. The BLASTn and phylogenetic analysis of the 16S rRNA of the MR1 gene found it shares a 95% homology to an aerobic bacillus Raoutella ornithilolytica. The bacteria which is usually found in an aquatic and hospital environment was found to possess a distinctive feature of being able to utilize 2,2-DCP as sole carbon source. The bacteria has cell doubling time of 23.11 h and maximum release of chloride ion at 0.257 mmol/L in 20 mM 2,2-DCP. Based on morphological and partial biochemical characteristics, the strain was found to be non-motile, Gram negative bacteria with red colonies that gave a positive catalase reaction. Conclusion, significance and impact of study: A better understanding of newly isolated microorganisms from the environment which can potentially be used as bioremediation tools in environmental management. This is the first reported case of Raoutella sp. that has the unique ability to degrade halogenated compound. Hence, the dehalogenation properties and capabilities of the bacteria deserve to be assessed further.

Clinical and polygraphic study of familial paroxysmal kinesigenic dyskinesia with PRRT2 mutation

Paroxysmal kinesigenic dyskinesia is a neurological condition characterised by brief attacks of involuntary movements triggered by sudden voluntary movements. We describe the clinical, polygraphic, and genetic features of an Italian family with paroxysmal kinesigenic dyskinesia. Paroxysmal kinesigenic dyskinesia manifested as brief choreoathetosic-dystonic attacks precipitated by sudden movements, varying in severity and frequency, amongst the four affected family members. The disorder follows an autosomal dominant transmission and affects female members. Mutation of SLC2A1, MR1, CACNA1A, and ATP1A2 genes was excluded by direct sequencing. Mutation analysis of the PRRT2 gene revealed a single nucleotide duplication, c.649dupC, resulting in the frameshift mutation p.Arg217Profs*8 in all affected members. Paroxysmal kinesigenic dyskinesia is the most common type of paroxysmal movement disorder and is often misdiagnosed clinically as epilepsy. We describe a family with paroxysmal kinesigenic dyskinesia associated with PRRT2 gene mutation, mild intrafamilial clinical heterogeneity, and benign course. [Published with video sequences].

Exceptionally high conservation of the MHC class I-related gene, MR1, among mammals

The major histocompatibility complex (MHC) class I-related gene, MR1, is a non-classical MHC class IA gene and is encoded outside the MHC region. The MR1 is responsible for activation of mucosal-associated invariant T (MAIT) cells expressing semi-invariant T cell receptors in the presence of bacteria, but its ligand has not been identified. A unique characteristic of MR1 is its high evolutionary conservation of the α1 and α2 domains corresponding to the peptide-binding domains of classical MHC class I molecules, showing about 90% amino acid identity between human and mouse. To clarify the evolutionary history of MR1 and identify more critically conserved residues for the function of MR1, we searched for the MR1 gene using jawed vertebrate genome databases and isolated the MR1 cDNA sequences of marsupials (opossum and wallaby). A comparative genomic analysis indicated that MR1 is only present in placental and marsupial mammals and that the gene organization around MR1 is well conserved among analyzed jawed vertebrates. Moreover, the α1 and α2 domains, especially in amino acid residues presumably shaping a ligand-binding groove, were also highly conserved between placental and marsupial MR1. These findings suggest that the MR1 gene might have been established at its present location in a common ancestor of placental and marsupial mammals and that the shape of the putative ligand-binding groove in MR1 has been maintained, probably for presenting highly conserved component(s) of microbes to MAIT cells.

Paroxysmal dyskinesias

Paroxysmal movement disorders are a relatively rare and heterogenous group of conditions manifesting as episodic dyskinesia lasting a brief duration. Three forms are clearly recognized, namely, paroxysmal kinesigenic (PKD), nonkinisegenic (PNKD), and exercise induced (PED). There have been major advances in the understanding of the pathophysiological mechanisms and the genetics of these disorders, leading to better clinical definitions based on genotype-phenotype correlations in the familial idiopathic forms. PKD is genetically heterogenous, but there is linkage to chromosome 16 in a number of families. PNKD is due to mutations of the MR-1 gene. PED is genetically heterogenous, but a number of familial and sporadic cases may be due to GLUT-1 gene mutations. The GLUT1 gene-related form of PED may respond to a ketogenic diet. Potassium and calcium channel mutations underlie the 2 main forms of episodic ataxia (EA1 and EA2), whereas benign torticollis of infancy may also be a calcium channel disorder.

Major histocompatibility complex class I-related chain A antigens stimulate endothelial cells proliferation and cause changes of their secreting functions

Objective To investigate the impact of major histocompatibility complex class Ⅰ -related chain A (MICA) antigen against endothelial cells and changes of secreting functions. Methods The endothelial cells were divided into three experimental groups (A5, A10, A25), which were stimulated with exogenous recombinant MICA antigen at 5, 10 and 25 μg/L respectively. Group A0 was added equivalent volume of PBS as control. The proliferation of endothelial cells was measured by MTF assay. The levels of metabolic product of PGI2 (6-keto-PGF1α), endothelin (ET-1), tissue plasminogen activator (t-PA) and its inhibitor (PAI) and soluble MICA (sMICA) in the supernatant of all groups were determined. Results A570 values in all experimental groups were higher than in control group. A570 values in both As and A10 groups were significantly higher than in control group and A25 group ( P ＜ 0. 05 ), but there were no significant differences between A5 and A10 groups (P ＞ 0. 05 ). The proliferation rate of 48 h was the highest in identical dosage. A570 of 48 h was 0. 458, 0. 446 and 0. 389 in A5, A10, A25 respectively. The proliferation rate at 72 h and 96 h was persistently decreased over time. There were significant differences (P ＜0. 05).The level of 6-keto-PGF1α in groups A10, A25 was 144. 6 and 132. 8 ng/L, which was lower than in group A0 (226. 5 ng/L) and A5 (232. 6 ng/L). The level of ET-1 in groups A10, A25 was 23. 6 and 25.8 ng/L,and that in group A0, A5 was 11. 8 and 10. 4 ng/L, respectively. The difference was statistically significant (P ＜ 0. 05). The level of t-PA in experimental groups were 161.2, 154. 2 and 157. 8 μg/L, and the level of PAI was 221.6, 248.5 and 252. 4 μg/L, respectively. sMICA in three experimental groups was 35.8,27. 4 and 21.8 ng/L respectively, which was lower than that in control group (352. 5 ng/L). There were significant differences between experimental groups and control group ( P ＜ 0. 05 ). Conclusion The small dosage of MICA antigen can stimulate endothelial cell persistent proliferation. Meanwhile, MICA antigen can cause the injury of endothelial cells and induce the enhanced coagulation function, the declined fibrinolytic function and the decreased level of sMICA. Key words: Major histocompatibility complex class; Endothelial cell; Proliferation; Prostacyclin; Endothelin

Bacteria, mucosal‐associated invariant T cells and MR1

Certain subpopulations of T lymphoctyes show innate-like properties that distinguish them from conventional T cells and thus have been collectively termed innate T cells. Two extensively studied subsets of innate T cells implicated in pathogen detection are invariant natural killer T (iNKT) cells and γδ T cells. Conventional T cells detect pathogens in a manner that is exquisitely antigen specific, based on discrimination of peptides bound to classical major histocompatibility complex (MHC) molecules. By contrast, innate T cells have only limited antigen discrimination and when antigen presentation has been implicated the antigen is not an unmodified peptide. For example, iNKT cells are activated by lipids presented by CD1d molecules,1 whereas certain γδ T cells are directly activated by ‘danger signals’ such as the small microbial product isopentenyl pyrophosphate.2 Their limited ligand discrimination and relatively larger clonal size allow innate T cells to mount earlier responses than conventional T cells. In comparison with conventional T cells, innate T-cell populations develop by a distinct ontogenic pathway and preferentially home to specific tissues. On the basis of these combined properties of innate T cells and the fact that their receptors and ligands have been highly conserved in evolution, it is attractive to propose that they represent ancient innate pathways of pathogen protection. Mucosal-associated invariant T (MAIT) cells were previously shown to have several properties in common with innate T cells, yet their physiological function remained unknown. Two new articles, Le Bourhis et al. published in Nature Immunology3 (reviewed here) and Gold et al. published in PLoS Biology4 implicate MAIT cells in the detection of bacterial infection in a manner restricted by the novel MHC class I-related molecule, MR1.

Diversity of HLA Class I and Class II Restricted Minor Histocompatibility Antigens in Graft-Versus-Leukemia Reactivity.

Abstract 4084Poster Board III-1019Donor lymphocyte infusion (DLI) can be an effective cellular immunotherapy for patients with hematological malignancies after HLA-matched allogeneic stem cell transplantation (alloSCT). The effect of DLI is mediated by donor derived T-cells recognizing minor histocompatibility antigens (mHags) encoded by single nucleotide polymorphisms (SNPs) on malignant cells of the recipient. Donor T-cells may also induce Graft-versus-Host Disease (GvHD) when directed against mHags with broad expression on non-malignant tissues. The aim of this study was to investigate the specificity and diversity of mHags recognized by T-cells in Graft-versus-Leukemia (GvL) reactivity.Activated (HLA-DR+) CD8+ and CD4+ T-cell clones were isolated from a patient successfully treated with DLI for relapsed chronic myeloid leukemia (CML) more than one year after HLA-matched alloSCT. GvL reactivity in this patient was accompanied with mild GvHD of the skin. Isolated T-cell clones were shown to recognize 13 different mHags. CD8+ T-cell clones were specific for HA-1 and HA-2 in HLA-A*0201, one unknown mHag in B*0801 and 4 unknown mHags in B*4001. CD4+ T-cell clones were specific for one unknown mHag in HLA-DQ and 5 unknown mHags in DR. By screening plasmid (class I) and bacteria (class II) cDNA libraries, we identified a mHag in HLA-DQ encoded by the PI4K2B gene (Griffioen et al., PNAS 2008), 4 mHags in HLA-DR encoded by the PTK2B, MR-1, LY75 and MTHFD1 genes (Stumpf et al., Blood 2009) and a mHag in B*4001 encoded by the TRIP10 gene. For the 3 T cell clones recognizing unknown mHags in B*4001, we performed Whole Genome Assocation scanning (WGAs). A panel of 60 EBV-LCL was retrovirally-transduced with B*4001 and tested for T-cell recognition. In parallel, genomic DNA was isolated and more than one million single nucleotide polymorphisms (SNPs) were determined by the Illumina beadchip array. Statistical analysis revealed significant association between T-cell recognition of EBV-LCL and the presence of coding SNPs in the SON DNA-binding protein and SWAP-70 genes. To get more insight into the role and potential use of the mHags in GvL reactivity and GvHD, all T-cell clones were analyzed in detail for reactivity against hematopoietic and non-hematopoietic cells. Hematopoietic cells included peripheral blood cells (monocytes, B-cells and T-cells), professional antigen presenting cells (APC) and leukemic cells (CML, ALL and AML). All CD8+ T-cell clones recognized (subsets of) peripheral blood cells as well as CML cells, except for the T-cell clone for TRIP10. Recognition of (subsets of) peripheral blood cells was also observed for all CD4+ T-cell clones, but CML cells were differentially recognized. CML cells were strongly recognized by the T-cell clones for MTHFD1 and the unknown mHag in HLA-DR, whereas no or low reactivity was observed for all other CD4+ T-cell clones. All CD8+ and CD4+ T-cell clones strongly recognized professional APC, including monocyte-derived dendritic cells and in vitro differentiated CML cells with APC phenotype. All T-cell clones were also capable of recognizing AML and ALL, except for the T-cell clone for TRIP10, which showed restricted recognition of AML-M4 and -M5 of monocytic origin. As non-hematopoietic cells, patient-derived fibroblasts were cultured with and without IFN-γ and tested for T-cell recognition. In the absence of IFN-γ, all T-cell clones failed to recognize fibroblasts, except for the T-cell clone for the unknown mHag in B*0801. After treatment with IFN-γ, additional reactivity was observed for the T-cell clones for SON DNA-binding protein and the unknown mHag in B*4001.Our data showed the specificity and diversity of mHags recognized by T-cells induced in a patient successfully treated with DLI for relapsed CML. The T-cell response was directed against 13 different mHags, of which 10 mHags in HLA class I and class II have now been identified by different techniques. Detailed analysis of T-cell recognition of hematopoietic and non-hematopoietic cells provides evidence that the mHags played different roles in the onset and execution of GvL and GvHD. Moreover, only one of the 10 identified mHags was expressed on fibroblasts after treatment with IFN-γ, indicating the characterization of mHags with potential relevance for T-cell based immunotherapy. Disclosures:No relevant conflicts of interest to declare.