Chain-related Gene Research Articles

Major Histocompatibility Complex Class I Chain-Related Gene Polymorphisms: Associated with Susceptibility to Kawasaki Disease and Coronary Artery Aneurysms

Kawasaki disease (KD) involves a complex interaction of immunoinflammatory process, cytokine activation, and genetic factors. We aimed to investigate whether genetic variations in a major histocompatibility complex (MHC) class could be used as markers of susceptibility in KD and coronary artery aneurysm lesions (CALs). Individuals were divided into following groups: (1) normal controls; (2) KD with CAL; (3) KD without CAL. Polymorphisms for MHC class I chain-related genes A (MICA) (rs2301747, rs2256184, rs2848716), MICB (rs2855804, rs3132464, rs2516400), BAT3 (rs750332), MSH5 (rs1150793), and chromosome 6 open reading frame 27 (C6orf27, rs707928) were genotyped with polymerase chain reaction and the TaqMan(®) allelic discrimination assay. Genotypes, alleles, and haplotype in each group were compared. Genotype and allele frequency of MICB*rs2516400 polymorphisms in each group were significantly different. MICB (rs2516400)*C-related genotypes/alleles are correlated with development of KD and CAL. Proportions of rs2516400*TT/TC/CC were (1) 1/39/60%, (2) 0/0/100%, and (3) 0/0/100%. Other single-nucleotide polymorphisms were not associated with KD susceptibilities. Haplotypes (rs2301747-rs2256184-rs2848716-rs2855804-rs3132464-rs2516400-rs750332-rs1150793-rs707928) G-G-G-C-T-C-T-A-A, C-A-G-T-T-C-T-A-A, and G-G-G-C-C-C-T-A-A were associated with higher susceptibilities for KD. The G-G-G-T-T-T-T-G-G and C-G-G-T-T-T-T-A-A haplotypes were associated with lower susceptibilities. MICB*rs2516400 polymorphisms and some MHC class I-related haplotypes are associated with KD susceptibility. MICB and MHC class I genetic variations might contribute to the pathogenesis of KD and CAL.

Positive association of major histocompatibility complex class I chain‐related gene A polymorphism with leukemia susceptibility in the people of Han nationality of Southern China

To assess the potential contribution of major histocompatibility complex class I chain-related gene A (MICA) polymorphisms toward the pathogenesis of leukemia, 107 leukemia patients and 162 ethnically matched controls from Hunan province, Southern China, were genotyped for the MICA polymorphism using polymerase chain reaction-sequence-specific priming (PCR-SSP) and sequence-based typing (PCR-SBT). The relevance between these genotypes and risk of leukemia was assessed by means of odds ratio (OR) with 95% confidence intervals (95% CIs). Allele frequencies of MICA-sequence and MICA-STR were different in leukemia patients in comparison with normal controls (both P < 0.05). MICA A5 was directly associated with leukemia (OR = 2.3257, Pc < 0.0005), whereas MICA A5.1 and MICA*008 were inversely associated with leukemia (OR = 0.5874, Pc = 0.0235 and OR = 0.5874, Pc = 0.0329, respectively). In addition, we found that homozygotes for MICA A5 (OR = 14.0659, 95% CI: 3.1627-62.5574, Pc < 0.0001) and MICA*010 (OR = 10.1053, 95% CI: 2.2139-46.1260, Pc < 0.0004) were at an increased risk for leukemia, whereas heterozygotes for MICA*008 and MICA A5.1 were linked to a decreased risk for leukemia (OR = 0.4609, 95% CI: 0.2799-0.7590, Pc = 0.0027). MICA allelic variation is associated with leukemia in Hunan Han population; the data also suggest that MICA gene polymorphism affects susceptibility to different clinical subtypes of leukemia.

Characterization of the major histocompatibility complex class I chain-related gene B (MICB) polymorphism in a northern Chinese Han population: The identification of a new MICB allele, MICB*023

Major histocompatibility complex class I chain-related gene B (MICB) has only been characterized for allelic variation in very few human populations. The MICB polymorphism remains largely unknown in Chinese populations. In this study, 104 healthy unrelated Han subjects recruited from central Inner Mongolia Autonomous Region, northern China, were investigated by sequence-based typing for MICB allelic variation, the association of MICB alleles with AluyMICB insertion/deletion dimorphism located in MICB intron 1, linkage disequilibrium of MICB with human leukocyte antigen (HLA)-B and MICA, and HLA-A-C-B-MICA-MICB haplotypic diversity. Ten kinds of MICB alleles were observed, among which MICB*005:02/010, MICB*002:01, and MICB*004:01 were the most frequent alleles with frequencies of 51.44, 16.35, and 11.54%, respectively. Significant linkage disequilibrium (LD) was observed for 9 of the 21 HLA-B-MICB haplotypes and 6 of the 17 MICA-MICB haplotypes with a frequency >1.5%. In particular, HLA-B*13:01 and HLA-B*13:02, both of which were frequently represented in this population, exhibited a distinct LD pattern with the MICB allele. A new MICB allele, MICB*023, was identified, which differed from MICB*005:02/010 by a single mutation of G to A at position 86 in exon 2, resulting in an amino acid change from arginine to histidine at codon 6. HLA-A*30-C*06-B*13:02-MICA*008:01-MICB*005:02/010 was the most common haplotype, with a frequency of 8.64% in this population. HLA-A*02-C*08-B*48-MICA*Del-MICB*009N demonstrated a frequency of 2.4% in this population. Our results provide for the first time data regarding the MICB genetic polymorphism in northern Chinese Han populations and will form the basis for future studies of the potential role of MICB in allogeneic organ transplantation and disease association in related ethnic groups.

MICB polymorphisms and haplotypes with MICA and HLA alleles in Koreans

Major histocompatibility complex (MHC) class I chain-related gene B (MICB) is located within the human MHC class I region. The location of MICB in the MHC region may imply the presence of linkage disequilibrium with polymorphic MICA and human leukocyte antigen (HLA) loci. MICB is also polymorphic; however, MICB polymorphisms have not been investigated in Koreans. Using sequence-based typing (SBT), we estimated the allelic frequencies of MICB and haplotypes with MICA, HLA-B, and HLA-DRB1 at high resolution in a population of 139 unrelated Korean individuals. Eight MICB alleles were identified. The most frequent allele was MICB*005:02/*010 (57.2%), followed by *002 (11.5%), *004 (8.3%), *005:03 (8.3%), and *008 (6.8%). The most common two-locus haplotypes were MICB*005:02/*010-MICA*010 (19.4%), MICB*005:02/*010-DRB1*15:01 (6.5%), and MICB*005:02/*010-B*15:01 (10.4%); the most common three-locus haplotypes were B*15:01-MICA*010-MICB*005:02/*010 (5.8%) and MICA*010-MICB*005:02/*010-DRB1*04:06 (10.4%); and the most common four-locus haplotype was B*15:01-MICA*010-MICB*005:02/*010-DRB1*04:06 (5.8%). This is the first study to provide information about MICB allele frequencies and haplotypes with HLA in Koreans. These study results should help understand mechanisms of disease association between the MICB locus and neighboring loci in Koreans.

Antibodies against heterogeneous nuclear ribonucleoprotein K in patients with cardiac allograft vasculopathy

Cardiac allograft vasculopathy (CAV) is the most serious long-term complication after cardiac transplantation. T-cell-mediated immune response has been implicated as the central mechanism for this form of graft rejection, but the role of humoral immunity is still controversial. This study investigated whether human leukocyte antigen (HLA) and non-HLA antibodies are associated with CAV and if their presence can be used to identify patients at high risk of developing CAV. Diagnosis of CAV was made by angiography and intravascular ultrasound (IVUS) technology. Sera from 48 heart transplant recipients were assessed for the presence of antibodies. Although anti-HLA or anti-major histocompatibility complex class I chain-related gene A (MICA) antibodies in patients with or without CAV were not statistically different, heterogeneous nuclear ribonucleoprotein K (hnRNP-K) was identified as a new antigenic target after the screening of a human coronary artery smooth muscle cells complementary DNA (cDNA) expression library with a serum sample from a CAV patient. Four years after transplantation, presence of anti-hnRNP-K antibodies was significantly higher in the IVUS-defined CAV group (85.3%) and angiography-defined CAV patients (90.5%) compared with the non-CAV group (p < 0.0001 and p = 0.0023 respectively). The presence of anti-hnRNP-K antibodies 4 years after the transplant is statistically associated with CAV disease, regardless of the diagnostic technique. Therefore, prospective detection of these antibodies could be proposed as a helpful biomarker in CAV diagnosis.

MICA genetic polymorphism and HLA-A,C,B,MICA and DRB1 haplotypic variation in a southern Chinese Han population: Identification of two new MICA alleles, MICA*060 and MICA*062

In this study, 201 healthy, unrelated Han subjects in Hunan province, southern China, were investigated by sequence-based typing (SBT) for the allelic variation of the human major histocompatibility complex (MHC) class I chain-related gene A (MICA). Nineteen MICA alleles were observed, among which MICA*008:01 predominated with gene frequency of 30.35%. There was significant linkage disequilibrium (LD) of MICA*012:01 with HLA-B*54 and HLA-B*55, which was not observed in a northern Chinese Han population. Haplotype HLA-A*11-C*07-B60-MICA*008:01 (9.16%) was highly specific to this southern Chinese Han population. The most common five-locus haplotype in this population was HLA-A*02-C*01-B*46-MICA*010-DRB1*09 (8.73%). A new MICA allele, MICA*060, was identified on an HLA-A*02-C*01-B*55:02-DRB1*14 haplotype through extended family analysis. MICA*060 has probably arisen from MICA*012:01. Another new MICA allele, MICA*062, was identified by screening 1432 subjects using polymerase chain reaction–sequence-specific priming technology. MICA*062 has probably derived from MICA*010. Of particular interest is that MICA*062 was carried on an HLA-C*08-B*48:01-DRB1*14 haplotypic segment, as HLA-B*48 has been consistently shown to be primarily linked to MICA gene deletion in east Asian populations. Our results provide new insight into MICA genetic polymorphism in human populations. The findings reported here are of importance for future studies on the potential role of MICA in allogeneic organ transplantation and disease association in populations of Chinese ancestry.

Upregulated mRNA expression of major histocompatibility complex class I chain‐related gene A in colon and activated natural killer cells of Chinese patients with ulcerative colitis

To explore the expression of major histocompatibility complex class I chain-related gene A (MICA) and its ligand in colonic mucosa and the role of MICA-natural killer (NK) group 2D (NKG2D) interaction in activating NK cells in ulcerative colitis (UC) patients. Intestinal mucosal biopsies were obtained from patients with UC and the controls. The expression of major histocompatibility complex class I-related gene (MIC) genes was determined by a reverse transcription polymerase chain reaction (RT-PCR) and the imaging of MICA expressed on colonic mucosa was measured by confocal microscopy resonance scanning. NKG2D and intracellular interferon (IFN)-γ expressions on NK cells were assayed by flow cytometry. The relative amount of MICA mRNA in the colonic mucosa of UC patients was significantly higher than in that of the controls (3.5408 ± 2.6658 vs 1.0477 ± 0.7201, P = 0.001), as were the major histocompatibility complex class I chain-related gene B (MICB) (8.9879 ± 3.2893 vs 4.6293 ± 1.2616, P < 0.001) and NKG2D mRNA expression (2.4395 ± 0.8147 vs 1.1624 ± 0.3954, P < 0.001). Confocal microscopy resonance scanning had shown that MICA was localized predominantly on the basolateral membranes of the epithelium. Further flow cytometry confirmed that the percentage of IFN-γ producer NK cells that expressed NKG2D in peripheral blood lymphocytes was higher in UC patients than in the healthy controls (45.36% ± 12.47% vs 27.45% ± 9.30%, P < 0.001). MICA, MICB and NKG2D were upregulated in the colonic mucosa of UC and were associated with activating NK cells with promoted NKG2D and IFN-γ production.

Impact of MICA-TM, MICB-C1_2_A and C1_4_1 microsatellite polymorphisms on the susceptibility to chronic periodontitis in Germany

The major histocompatibility complex class I chain-related gene A (MICA)-TM exon 5 trinucleotide polymorphism, the MICB-C1_2_A intron 1 dinucleotide polymorphism and the tetranucleotide polymorphism C1_4_1 located in the major histocompatibility complex class I region on chromosome 6 were shown to influence various chronic inflammatory conditions. We investigated the association of these microsatellite polymorphisms with chronic periodontitis, a highly prevalent oral inflammatory disease in 389 periodontitis patients and 771 healthy controls with South German genetic background. Genotyping of the MICA-TM, MICB-C1_2_A and C1_4_1 microsatellite polymorphisms was performed by PCR amplification and fragment analysis. Global frequency distribution of MICB-C1_2_A (P = 0.006) and C1_4_1 (P = 0.028) alleles was significantly different between both study groups. Allele-specific analysis revealed that the MICA-TM allele A5 was more prevalent among male periodontitis patients [P = 0.0001; odds ratio (OR) 2.17, 95% confidence interval (CI) 1.55-3.03]. In C1_4_1 allele, three was significantly higher in healthy controls (P = 0.006; OR 0.74, 95% CI 0.60-0.91). Two haplotypes (MICA:A5-C1_4_1:5; P = 0.002; OR 2.63, 95% CI 1.46-4.74 and MICB:CA16-C1_4_1:3; P = 0.014; OR 0.68, 95% CI 0.50-0.92) showed significant differences between periodontitis patients and controls. The MICA-TM, MICB-C1_2_A and C1_4_1 microsatellite polymorphism seem to influence the individual susceptibility to chronic periodontitis in patients with German genetic background.

Sequence‐based typing of major histocompatibility complex class I chain‐related gene A alleles by use of exons 2–5 information

The polymorphic MICA (major histocompatibility complex class I chain-related gene A) (Gene ID: 100507436) gene products are a ligand of the activating natural killer cell receptor, NKG2D. Their clinical importance spans from solid organ transplantation to bone marrow transplantation and disease susceptibility. Typing of MICA genes by sequencing is hampered by an exon 5 short tandem repeat, the definition of which is critical for the final allelic and functional assignment. We present a novel sequencing approach, which uses group-specific (7T/8T) exon 5 polymerase chain reactions (PCRs) and facilitates hemizygous exon 5 MICA-PCR in approximately 70% of the tested individuals. With this method we typed the International Histocompatibility Workshop Group MICA reference panel (40 cell lines) as well as 110 healthy South German blood donors. All ambiguities, with the exception of MICA*008:01/008:04 (synonymous substitution in exon 1) and MICA*009:01/049 (nonsynonymous substitution in exon 6), could be resolved with our method. Analysis of Hardy-Weinberg equilibrium for our cohort showed no significant difference between expected and observed frequencies of MICA alleles (P = 0.6142). The three most frequent alleles in our blood donor cohort were MICA*008:01/008:04 (40.5%), MICA*002:01 (13.2%), and MICA*009:01/049 (8.6%). The 7T polymorphism was observed in 67.7% and the 8T polymorphism in 32.3% of our blood donor cohort. Individuals (24.5%) tested were homozygous. The approach described in this paper is suitable for accurate sequencing of large sample numbers, including direct readout of exon 5 sequences. It is compatible with laboratory automation and commercial human leukocyte antigen analysis software tools. It may therefore be applied in large clinical trials.

Anti-Angiotensin Type 1 Receptor Antibodies Associated With Antibody Mediated Rejection in Donor HLA Antibody Negative Patients

Angiotensin type 1 receptor (AT1R) mediates most physiologic and pathophysiologic actions of its endogenous ligand, angiotensin II, with overactivity leading to vascular remodeling and hypertension. Antibodies to AT1R are implicated in several vascular pathologies. The aim of our study was to determine the impact of antibody to AT1R on clinical outcomes including antibody mediated rejection (AMR), with or without C4d deposition, in patients whose sera contained no donor human leukocyte antigen (HLA)-specific antibody (HLA-DSA). Pretransplant sera from 97 recipients and sera obtained at the time of acute rejection (AR) were tested by Luminex-based single-antigen bead assays to determine HLA-DSA and antibodies to major histocompatibility class I chain-related gene A (MICA). The presence of antibody to AT1R was determined by a cell-based ELISA method using a cutoff of 17 units to distinguish high from low binding. Sera from 63 recipients were determined to have no HLA-DSA and no donor-specific MICA antibodies pretransplant and at the time of AR, and 16 of these recipients were diagnosed with AR including 7 with AMR and 9 with cellular AR (cell-mediated rejection). High-binding AT1R antibodies were identified for six of seven in the AMR+ group and zero of nine in the cell-mediated rejection+ group (P=0.0009). A strong association was observed between the presence of high binding to AT1R and AMR in recipients whose sera contained no antibody to donor HLA or MICA. Assessing the AT1R antibody status along with the HLA-DSA provides additional information to determine the immunologic risk for recipients.

Genetic susceptibility to Behcet's disease: role of genes belonging to the MHC region

To review the progress in the field of MHC-related genetic susceptibility to Behçet's disease (BD). Systematic review of the English literature between 1 January 1980 and 31 January 2010 using Medline. Case-control, population-based, observational cohort studies investigating the association between BD and HLA-B*51 subtypes, classical and non-classical HLA alleles and other HLA-related genes were selected. The geographical distribution of BD and these susceptibility genes was also taken into consideration. Case and familial case reports were excluded except for case series with more than two patients. Ninety articles plus 17 obtained from other sources were included in the systematic review. We have found high evidence that a core component of genetic susceptibility to BD is within the MHC region being primarily related to an HLA-B*51 subtype: HLA-B*5101/B*510101. Moreover, HLA-A*26, HLA-B*15, HLA-B*5701 and TNF-α -1031C were independently associated with BD. Data suggest that other HLA (HLA-C, HLA-DR) and HLA-related [MHC Class I chain-related gene A (MIC-A), TNF-α] genes may play a role in BD co-susceptibility or pathogenesis. Finally, the distinctive geographical distribution of BD suggested an evolutionary selection of HLA-B*51 subtypes as the major susceptibility factors for BD. Further studies must be addressed to clarify the functional relevance of the different genes found to be associated with disease susceptibility and the potential interactions between genes located within and outside the MHC region.

IL‐2‐activated haploidentical NK cells restore NKG2D‐mediated NK‐cell cytotoxicity in neuroblastoma patients by scavenging of plasma MICA

NK group 2D (NKG2D)-expressing NK cells exhibit cytolytic activity against various tumors after recognition of the cellular ligand MHC class I chain-related gene A (MICA). However, release of soluble MICA (sMICA) compromises NKG2D-dependent NK-cell cytotoxicity leading to tumor escape from immunosurveillance. Although some molecular details of the NKG2D-MICA interaction have been elucidated, its impact for donor NK (dNK) cell-based therapy of solid tumors has not been studied. Within an ongoing phase I/II trial, we used allogeneic IL-2 activated dNK cells after haploidentical stem cell transplantation for immunotherapy of patients with high-risk stage IV neuroblastoma. NKG2D levels on activated dNK cells increased strongly when compared with freshly isolated dNK cells and correlated with enhanced NK-cell cytotoxicity. Most importantly, elevated sMICA levels in patients plasma correlated significantly with impaired dNK-cell-mediated cytotoxicity. This effect could be reversed by high-dose infusion of activated dNK cells, which display high levels of surface NKG2D. Our data suggest that the provided excess of NKG2D leads to clearance of sMICA and preserves cytotoxicity of dNK cells via non-occupied NKG2D. In conclusion, our results identify this tumor immune escape mechanism as a target to improve immunotherapy of neuroblastoma and presumably other tumors.

Association of MICA gene polymorphism and serum soluble MICA level with colorectal cancer

To investigate whether the major histocompatibility complex class I chain-related gene A gene (MICA) polymorphism and serum soluble MICA level were associated with the occurrence and development of colorectal cancer. DNA samples from 117 colorectal cancer patients and 113 healthy individuals from Yangzhou in Jiangsu province were genotyped by using the polymerase chain reaction (PCR) and sequence-specific primer (SSP) method and PCR based sequencing. In addition, polymorphism at position 129 was also analyzed by PCR-SSP. Serum levels of soluble MICA were measured by a sandwich ELISA method. Neither the extracellular nor the transmembrane region polymorphisms of MICA gene were associated with the occurrence and the different stages of colorectal cancer. In contrast, the frequency of the methionine residue at position 129 was significantly decreased in the patient group. Soluble MICA levels in sera were increased in the late stages of colorectal cancer. Although there was no genetic susceptibility attributed to MICA gene polymorphism with regard to development of colorectal cancer, serum levels of soluble MICA may be a diagnostic marker of advanced stages.

MICA polymorphism: biology and importance in immunity and disease

The human major histocompatibility complex class I chain-related gene A (MICA) is one of the genes in the HLA class I region of chromosome 6. Unlike HLA classical class I gene products, MICA does not present any antigen but acts as a ligand for several immune cells including natural killer (NK) cells bearing NKG2D receptors. MICA is the member of the non-classical class I family that displays the greatest degree of polymorphism. MICA alleles can be divided into two large groups with the polymorphisms found in alpha3 domains. This division could be explained by a possible polyphyletic origin that is in line with recent findings from evolutionary, population and functional studies of this gene. MICA polymorphisms are associated with a number of diseases related to NK activity, such as viral infection, cancer and allograft rejection or graft-versus-host disease (GVHD). The mechanisms underlying these associations include NK cell-mediated cytotoxicity and MICA shedding to produce immunosuppressive soluble MICA particles. The MICA-induced humoral response has attracted interest recently because of its possible role in graft rejection in solid organ transplantation. Here, we discuss the genetics and biology of the MICA gene and its products, and their importance in disease.

MICA polymorphism in a northern Chinese Han population: The identification of a new MICA allele, MICA*059

The major histocompatibility complex class I chain-related gene A (MICA) in humans, located 46 kb centromeric to human leukocyte antigen (HLA)-B, is highly polymorphic. In addition to its primary role in immune surveillance, recent data highlight the importance of MICA in organ transplantation and in susceptibility to some diseases. In this study, 104 healthy, unrelated Han subjects recruited from central Inner Mongolia Autonomous Region, northern China, were investigated by sequence-based typing and fragment analysis for MICA allelic variation, MICA-HLA-B linkage disequilibrium, and HLA-A-Cw-B-MICA haplotypic diversity. Nineteen MICA alleles were observed, the most frequent of which were MICA*00801, MICA*010, MICA*00201, MICA*00901, and MICA*045, with gene frequencies of 23.08%, 18.75%, 12.02%, 12.02%, and 8.17%, respectively. The peculiarity in HLA-B-MICA haplotypic configurations was also uncovered. In particular, there was a clear-cut dichotomy between MICA*00801 and MICA*045 in their linkage to members of HLA-B*13 lineage, which was frequently represented in this population. A new MICA allele, MICA*059, was identified, which appeared to be evolutionarily linked to MICA*045. Haplotype HLA-A*30-Cw*06-B*1302-MICA*00801, previously not reported in other populations, was found with a frequency of 8.65% in this population. Our results provide new data about MICA genetic polymorphism in Chinese Han populations, which will form the basis for future studies of the potential role of MICA in allogeneic organ transplantation and disease susceptibility in related ethnic groups.

MICApolymorphisms and haplotypes withHLA‐BandHLA‐DRB1in Koreans

Major histocompatibility complex (MHC) class I chain-related gene A (MICA) is located within the human MHC, centromeric to HLA-B and telomeric to HLA-DRB1. The location of MICA in the MHC indicates the presence of linkage disequilibrium with human leukocyte antigen (HLA). Like HLA, MICA is highly polymorphic; however, the information available for MICA polymorphisms is not as comprehensive as that for HLA polymorphisms. We estimated the allelic frequencies of MICA and haplotypes with HLA-B and HLA-DRB1 at high-resolution in a population of 139 unrelated Korean individuals by applying the newly developed method of sequence-based typing (SBT). A total of 17 MICA alleles were identified. The most frequent allele was MICA*010 (19.4%), followed by alleles *00201 (17.6%), *00801 (14.7%), *01201 (9.4%), *004 (8.3%) and *049 (7.9%). The most common two- and three-locus haplotypes were HLA-B*1501-MICA*010 (10.4%), MICA*010-HLA-DRB1*0406 (5.8%) and HLA-B*1501-MICA*010-HLA-DRB1*0406 (5.8%). This is the first study to provide such high-resolution information on the distribution of haplotypes comprising MICA, HLA-B and HLA-DRB1 in Korean individuals, a level of resolution made possible by use of the SBT method. The results of this study should help determine the mechanisms underlying diseases associated with MICA polymorphisms in Korean individuals.

Study of the soluble MICA in gastric cancer patients in different stages and relation with prognosis

Objective To observe the features of soluble MHC class I chain-related gene A (sMICA)in patients with gastric cancer of different differentiation degrees, the relationship between sMICA and the stage of gastric cancer and the relationship between sMICA and the metastasis of gastric cancer. To provide a new and useful marker in the differential diagnosis and staging of gastric cancer. Methods The peripheral blood examples of 200 gastric cancer patients and 60 health donors were collected. The serum levels of soluble MICA of peripheral blood were determined by MICA-specific enzyme-linked immunosorbent assay.Results The serum levels of sMICA in the patients with gastric cancer and health donors were (359.45 ±114.15) pg/ml and (210.07 ±31.01) pg/ml respectively. sMICA levels in the patients were significantly higher than those of the health donors (t =16.58, P 0.05). The serum levels of sMICA in the patients with gastric cancer steped up gradually while increasing of the TNM stages.There were significant differences between stage Ⅱ and Ⅲ, stage Ⅱand Ⅳ, stage Ⅱ and Ⅳ (P <0.05). The serum levels of sMICA in the patients with gastric cancer steped up gradually while aggravating of metastasis extent.Conclusion sMICA-release of MICA from cancer cells may reduce the expression of NKG2D. This may impair NKG2D-mediated immune surveillance of gastric cancer and leads to the tumor escaping; In the patients with gastric cancer, the serum levels of sMICA correlate with cancer stage and metastasis but show no correlation with cell differentiation. Key words: Stomach neoplasms; Genes; MHC class Ⅰ; Prognosis

Impact of MICA and Other Immunogenetic Polymorphisms On Clinical Presentation of T Cell Large Granular Lymphocyte Leukemia.

Abstract 1094Poster Board I-116T cell large granular lymphocyte leukemia (T-LGL) is a rare lymphoproliferative disorder marked by clonal expansion of cytotoxic T lymphocytes (CTL). T-LGL may be a result of clonal outgrowth from initially polyclonal CTL responses seen in the context of viral infections, autoimmune conditions, or tumor surveillance. Similar to classic autoimmune diseases, such as rheumatoid arthritis, multiple sclerosis or aplastic anemia, immunogenetic predisposition to T-LGL is suggested by association with certain immunogenetic polymorphisms including human leukocyte antigen (HLA) and killer immunoglobulin receptor (KIR). In addition to KIR-ligand/KIR interactions, the quality of CTL may be determined by the binding between the major histocompatibility complex class I chain-related gene A (MICA) and its ligand NKG2A. Over fifty five MICA alleles have been documented to date. A number of autoimmune and oncologic conditions such as systemic lupus erythematosus, rheumatoid arthritis, psoriasis, Crohn's disease, cervical cancer, or oral squamous cell carcinoma were all reported to be associated with MICA polymorphism.We hypothesized that specific MICA polymorphisms may be associated with exaggerated CTL responses in T-LGL and may therefore impact clinical features of the disease such as immune cytopenias. We have collected a large well annotated cohort of patients with T-LGL (n=86). HLA, MICA, and KIR alleles were resolved by established molecular techniques. Diagnosis of T-LGL was established by flow cytometry, T cell receptor γ chain rearrangement, Vβ typing, and assessment of peripheral blood smear. Categorical and survival methods of data analysis were used to examine the association between MICA, HLA, and KIR polymorphisms with type and degree of cytopenias, LGL T cell count, response to therapy, splenomegaly, and overall survival.Caucasians accounted for 96.5% of the study cohort (median age, 64 years; 55% males). Neutropenia, anemia, and thrombocytopenia were found in 63.4%, 50%, and 23.5% of the patients, respectively. Bicytopenia and pancytopenia were found in 26% and 13% of subjects, respectively. Median LGL T cell count was 1800 cells/μL (range, 280-20,580 cells/μL). Splenomegaly was found in 47% of patients. Compared to healthy controls (2N=308), our cohort was overrepresented by MICA*A5.1 (population frequency, 0.59 in T-LGL vs. 0.37 in controls, p<0.001). As opposed to the patients carrying MICA*A4 (p=0.01), those with MICA*A5.1 (p=0.025) or MICA*008 (p=0.025) were less likely to present with splenomegaly. MICA*A6 carriers were more likely to have thrombocytopenia (p=0.04). Since immunogenetic predisposition is often encoded by complex genetic traits, we have also examined the impacts of HLA class I, II and KIR-ligand/ KIR on clinical presentation of T-LGL. Immunogenetic factors associated with anemia as a predominant feature included HLA-DR7 (p=0.003), Bw4-KIR3DL1 (p=0.03), or having less than 3 inhibitory KIR ligand mismatches (p=0.025). Subjects with HLA-Bw6 (p=0.02) and HLA-A*24 (p=0.05) were more likely to have neutropenia, whereas the patients with HLA*A11 were more likely to have thrombocytopenia (p=0.01). HLA-A*24 (p=0.004), HLA-B*15 (p=0.03), and KIR2DL5 (p=0.045) were associated with poorer clinical response to therapy in contrast to those with HLA*01 (p=0.008) and HLA-B*58 (p=0.045) associated with more favorable clinical responses. In contrast to HLA-B*27 carriers with higher likelihood of splenomegaly (p=0.01), patients with HLA-Bw4-KIR3DL1 (p=0.046), HLA-DR3 (p=0.005), or HLA-DQ2 (p=0.028) were less likely to develop splenomegaly. We did not detect any associations with overall survival.In summary, the overrepresentation of MICA*A5.1 among T-LGL patient had limited impact on clinical outcomes. In contrast to numerous associations between HLA and KIR with clinical presentation of T-LGL, the associations for MICA alleles in our cohort were limited to less likelihood of splenomegaly for MICA*A5.1 and MICA*008 carriers and to higher propensity towards thrombocytopenia for those with MICA*A6. Altogether, our findings extend the evidence for a role of immunogenetic factors in the pathogenesis and clinical outcomes of T-LGL. DisclosuresNo relevant conflicts of interest to declare.

Donor-recipient mismatches in MHC class I chain-related gene A in unrelated donor transplantation lead to increased incidence of acute graft-versus-host disease

AbstractThe polymorphic products of major histocompatibility complex class I–related chain A (MICA) genes are important in solid organ transplantation rejection. MICA expression is limited to gut epithelium and may play a role in triggering acute graft-versus-host disease (aGVHD). A total of 236 recipients of unrelated donor transplantation were studied. Donor-recipient human leukocyte antigen (HLA) match was 10/10 human leukocyte antigen (HLA-A, -B, -C, -DRB1, -DQB1) in 73% and MICA mismatch in 8.4%. Because of physical vicinity of the loci, MICA mismatch was significantly associated with mismatch at HLA-B and HLA-C. A higher rate of grade II-IV aGVHD was seen in MICA-mismatched patients (80% vs 40%, P = .003) irrespective of degree of HLA matching (HLA 10/10 match: 75% vs 39%, P = .02) and HLA any mismatch (83% vs 46%, P = .003). The rate of grade II-IV gastrointestinal aGVHD was also higher in MICA-mismatched patients (35% vs 17%, P = .05). We conclude that MICA may represent novel a transplantation antigen recognized by human allogeneic T cells. This study was registered at ClinicalTrials.gov (Identifier NCT00506922).

The role of major histocompatibility complex class I chain-related gene A antibodies in organ transplantation

Major histocompatibility complex class I chain-related gene A (MICA) antigens are expressed on the endothelium, they are polymorphic and have been shown to be recognized by antibodies produced by transplant recipients. Methods for detection of these antibodies have become available. In the 15th International Histocompatibility Workshop, a study for MICA antibody testing and of MICA genotyping was organized. Antibodies against MICA antigens have been determined either using cells transfected with MICA alleles or recombinant MICA antigens. MICA epitopes were characterized by empirical study of human sera and by correlation with MICA polymorphic amino acids. Sera were absorbed with cells transfected with MICA alleles and site-directed mutagenesis was employed to analyze complex sera. A number of clinical studies have shown associations of antibodies against MICA with decreased survival of kidney transplants and in one investigation with acute rejection in recipients of heart allografts. In addition to the HLA antigens, which elicit a strong immune response against allografted organs, the MICA antigens may be recognized as foreign and induce the production of MICA-specific antibodies. Antibodies against MICA have been associated with a decrease in the survival of organ allografts. The results suggest the MICA antigens are transplantation antigens that can induce an immune response associated with graft failure.