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PubMed1988

Decreased expression of HLA class II antigens on human uveal melanoma cells after in vivo X-ray irradiation.

In order to determine the presence of HLA antigens on human uveal melanomas, we tested anti-HLA monoclonal antibodies on tissue sections of these tumors. A great variety in expression of HLA class I and II antigens was present. A significantly lower expression of HLA class II antigens was present on uveal melanomas that had been irradiated before enucleation. These tumors lacked a lymphocytic infiltrate in comparison with nonirradiated tumors. These data suggest that radiotherapy affects expression of histocompatibility antigens on tumors.

Adult↗
PubMed1986

Autologous B lymphoblastoid cell lines and long-term cultured T cells as stimulators in the mixed lymphocyte reaction: analysis of the role of HLA class II antigens as stimulatory molecules.

Human activated T cells, long-term cultured in the presence of interleukin 2 (IL 2), were compared with autologous Epstein Barr virus-transformed B lymphoblastoid cell lines for expression of human leukocyte (HLA)-HLA-DR and -DQ antigens and for ability to induce proliferative responses in autologous and allogeneic lymphocytes. Immunofluorescence analysis performed with a panel of monoclonal antibodies (mAb) specific for HLA-DR or -DQ antigens did not reveal any significant difference in the expression of HLA-DR antigens but revealed reduced expression of HLA-DQ antigens on two out of four T cell lines tested. No obvious difference could be detected in the two-dimensional gel electrophoretic profile of HLA-DR and -DQ beta-chains synthesized by the autologous pairs of B and T cell lines. In contrast with previous reports, the IL 2-dependent cell lines consistently induced alloproliferative responses in standard 6-day mixed lymphocyte cultures; however, these responses were severalfold lower than those elicited by the autologous B lymphoid lines. Both anti-HLA-DR and anti-HLA-DQ mAb blocked the proliferative responses induced by the B cell lines but did not affect those generated by the T cell lines, suggesting that the latter cells induce T lymphocyte activation via a mechanism independent of HLA-DR or -DQ antigen expression on their surface. Addition of IL 2 to the mixed cultures with B cell lines as stimulators did not affect the outcome of the proliferative responses but partially or completely reversed the blocking activity of the mAb. In contrast, IL 2 significantly enhanced the alloproliferation induced by the T lymphoblastoid cell lines, and the anti-HLA class II mAb partially antagonized this effect. Taken together, these data suggest that unlike the HLA-DR and -DQ gene products on B cells, those on IL 2-dependent long-term cultured T cells do not play a direct or primary stimulatory role in the mixed lymphocyte reaction; the reduced levels of alloproliferation induced by the T cell lines are, at least in part, due to a defective production of endogenous IL 2 by the responder lymphocytes rather than to a defective expression of IL 2 receptors by the alloproliferative T cell subset; and the anti-HLA class II mAb in these cultures act only at the responder cell level, since they can efficiently block the enhancement of T cell proliferation triggered by exogenous IL 2, but not the proliferative responses induced by T cell lines in standard conditions.

Antibodies, Monoclonal↗
PubMedDate not supplied

[Distribution of HLA class II antigens and allele linkage disequilibrium in the population of Vojvodina].

INTRODUCTION: Polymorphism of human leucocyte antigens (HLA) is important in transplantation medicine, anthropological studies and paternity testing. MATERIAL AND METHODS: We investigated polymorphisms of HLA class II in population of Vojvodina by means of serologic typing using microlymphocitotoxicity test. We calculated the HLA-DR and HLA-DQ gene frequencies in 174 subjects. Haplotype frequencies, coefficient of linkage disequilibrium (delta values) and their statistical significant levels, were analyzed on the basis of these data. RESULTS: The most frequent HLA-DR and HLA-DQ alleles were: DR5(11) (gene frequency 0.138), DR4 (gene frequency 0.083), DR1 (gene frequency 0.077), DQ1 (gene frequency 0.388), DQ3 (gene frequency 0.197), and DQ2 (gene frequency 0.09). The highest positive values of coefficient of linkage disequilibrium (delta) were calculated for the following haplotypes: DR1DQ1 (delta value 0.07308708), DR2DQ1 (delta value 0.059846528), DR3DQ2 (delta value 0.06193263), DR2(15)DQ1 (delta value 0.039186022), DR5(11)DQ3(7) (delta value 0.04969439), DR7DQ2 (delta value 0.057985517). Significant differences between observed vs. expected haplotype frequencies were also considered for these haplotypes. CONCLUSION: This study indicates distinctiveness and specificity of the population of Vojvodina and highlights the importance of determining HLA frequencies in endogamic groups of Serbia.

Gene Frequency↗
PubMed1990

HLA-class II antigen expression in human heart-lung allografts.

Long-term survival in heart-lung transplantation has ben hindered by the development of bronchiolitis obliterans (OB), which is believed to be a manifestation of chronic rejection of the lung. Since HLA-class II antigens are involved in the rejection response, the distribution of the class II products HLA-DR, HLA-DQ, and HLA-DP were studied in normal lung, and in transplanted lung with and without OB, utilizing frozen-section immunohistochemical techniques. All three allelic products are usually expressed on the epithelial, endothelial, and mesenchymal components of the lung. Sequential transbronchial biopsies from 4 recipients before and concurrent with the diagnosis of OB were stained with serial dilutions of monoclonal antibodies to assess the level of expression of the above class II products. Increased levels of HLA-DR and HLA-DP antigens may be seen on the bronchial and bronchiolar epithelium during OB, but the changes are subtle and complicated by many other variables. Additional studies are needed to confirm these preliminary results.

Bronchiolitis Obliterans↗
PubMed1989

Class I and class II HLA antigen expression by transitional cell carcinoma of the bladder: correlation with T-cell infiltration and BCG treatment.

HLA class I and II glycoproteins from transitional cell carcinoma (TCC) and from perineoplastic and healthy vesical mucosa were characterized together with infiltrating cells by means of immunochemistry using specific monoclonal antibodies on frozen sections obtained during resection or radical cystectomy. Specimens were taken from 11 patients with TCC and five with healthy bladder mucosa. Four patients with TCC and four with healthy mucosa had been previously treated with a course of intravesical bacillus Calmette-Guerin (BCG). Ten out of 11 TCC samples expressed class I glycoproteins with a membrane pattern (diffuse in seven, focal in three) as normal epithelial cells from either controls or perineoplastic bladder. Interestingly, eight out of 11 TCC samples expressed class II antigens on their membrane that were also present in six cases in the perineoplastic tissue while the epithelial cells from four out of five normal bladders were completely negative. The epithelial display of class II antigens in the non-neoplastic areas and in the normal bladder correlates (p less than 0.001) with the degree of cellular infiltrate while such a relationship was not found between the HLA II expression of neoplastic cells and the infiltrate. BCG treatment was associated with a higher amount of inflammatory cells, prevalently T "activated" cells (CD5+,DR+), with a CD4/CD8 ratio always greater than 1. In the light of the role played by HLA glycoproteins in immune mechanisms, these results could help explain the positive action of BCG and the relative immunosensitivity of TCC.

Aged↗
PubMed1989

Human myelin basic protein-specific cytolytic T lymphocyte clones are functionally restricted by HLA class II gene products.

Cellular immune reactions against the autoantigen myelin basic protein (MBP) are strongly implicated in the occurrence of postinfectious and postvaccination encephalomyelitis. Clinical autoimmune encephalomyelitis in experimental animals can be transferred with cloned MBP-specific cytolytic major histocompatibility complex Class II-restricted T lymphocytes. The HLA restriction pattern of specific proliferative and cytolytic functions of two human MBP-specific cytotoxic T lymphocyte clones, derived from two different multiple sclerosis patients, was analyzed in detail. Using monoclonal antibodies against various HLA gene products and allogeneic Epstein-Barr virus-transformed B cells as antigen-presenting cells and as targets for cytolysis, it was found that MBP-specific functions of the T cell clones was restricted by HLA class II antigens, and, more specifically, by molecules encoded for by DR locus genes.

Antigen-Presenting Cells↗
PubMed1999

HLA class II immunogenetics and incidence of insulin-dependent diabetes mellitus in the population of Cantabria (Northern Spain).

HLA class II genes were analyzed to study IDDM susceptibility in Cantabria (Northern Spain). Patients showed highly significant increases in DRB1*0301 (RR = 4.581, p < 0.00005), DRB1*0401 (RR = 2.6, p < 0.05), DRB1*0402 (RR = 8.78, p < 0.05) and DRB1*0405 (RR = 14.73, p < 0.005). Highly significant diferences were in the DQA1*0301 (RR = 3.62, p < 0.000005) and DQA1*0501 (RR = 2.13, p < 0.05) alleles. DQB*0201 (RR = 4.1, p < 0.00005) and DQB1*0302 (RR = 5.42, p < 0.000005) alleles were also significantly increased. A significant increase in DRB1*0402-DQA1*0301-DQB1*0302 (RR = 16.18, p < 0.05), DRB1*0405-DQA1*0301-DQB1*0302 (RR = 16.12, p < 0.05), DRB1*0301-DQA1*0501-DQB1*0201 (RR = 4.58, p < 0.00005) and DRB1*0401-DQA1*0301-DQB1*0302 (RR = 4.36, p < 0.005) was apparent in the diabetic group, while the DRB1*1501-DQA1*0102-DQB1*0602 and DRB1*1401-DQA *0104-DQB1*05031 protective haplotypes (RR = 0.17 and 0.09, p < 0.0005 and 0.05, respectively) were significantly lower in patients. The absence of Asp57 and the presence of Arg52 were associated with disease in a dose-dependent manner. Several genotypes encoding the identical DQalpha52/DQbeta57 phenotype carried very different RRs. Finally, the Cantabrian population has the highest incidence of IDDM reported for Spain (15.2 of 100.000 in the 0-14 age group, Poisson's 95% CI: 10.6-19.3).

Adolescent↗
PubMed1995

Analysis of HLA-class II DQA1, DQB1, DRB1 and DPB1 in Italian multiple sclerosis patients.

We studied the allelic constitution at the HLA class II DQA1, DQB1, DRB1 and DPB1 in 94 Italian multiple sclerosis (MS) patients and 98 controls. No significant increase in the frequency of DR2 alleles was detected among MS patients, as previously observed both in European and some Italian studies. A slight increase was found for the DQA1*0301 and DQB1*0602 alleles in the MS patients. No significant association was found with the glutamine residue at position 34 of the DQ alpha chain, which was noted previously in MS patients from northern Europe.

Alleles↗
PubMed1989

Congenital immunodeficiencies associated with absence of HLA class II antigens on lymphocytes result from distinct mutations in trans-acting factors.

Coordinate regulation of HLA class II gene expression during development and coinduction of class II genes by soluble factors suggests that common trans-acting factor(s) control expression of these genes. In B-lymphoblastoid cell lines derived from two independent class II-deficient bare lymphocyte syndrome patients, we observed a drastic decrease in transcription rates of the class II genes. When these cell lines are fused, class II genes are reexpressed, indicating that immunodeficiencies in bare lymphocyte syndrome patients are the result of two distinct mutations. Further studies show that genes governing the expression of class II antigens fall into at least three complementation groups; two of these were previously unidentified in mutant cell lines generated in vitro. In addition, we report the identification of two discrete complexes, NFX1.1 and NFX1.2, that bind to the DRA X consensus element. Though the mutation in at least one mutant line generated in vitro (RJ2.2.5) affects products functioning via interaction with the X box, clear alterations in either NFX1.1 or NFX1.2 are not found in any of the mutant cell lines.

Cell Line↗
PubMed1986

Simplification of two-dimensional gel patterns of HLA class II antigens.

Two-dimensional gel electrophoresis of material immunoprecipitated from radiolabeled cells by anti-HLA class II monoclonal antibodies has been a useful technique but the patterns observed have varied considerably between laboratories. In this study we investigated the parameters that vary between different laboratories. We found that heterogeneity due to post synthetic modification of beta and alpha chains of DR and DQ can be avoided by labeling cells for 30 min with 35S-methionine. A mixture of ampholytes pH range 3.5-10:5-7 of 1:4 run for 3000 V/h gave the best resolution of beta and alpha chains. With this technique we could clearly reveal differences in the DR beta-2 chains of those DR2 haplotypes, Dw2, Dw12 and LD'tb24. The Dr beta 1 position varied between different DR types.

Antibodies, Monoclonal↗
PubMed1996

African-American HLA class II allele and haplotype diversity.

Molecular genetic techniques were used to type nine loci in the HLA class II region in 241 unrelated African-Americans from New York City (NYC). Several effects attributable to recent genetic admixture were evident: the number of distinct class II alleles and haplotypes was larger in the African-Americans than in people of African or European origin, the allele frequencies were more consistently even, and linkage disequilibrium was present across the entire class II region. The African-American DRB1 allele frequencies almost always fell between frequencies among samples from northern Europe and the Gambia, two possible founding populations. The exceptions are attributed to the contribution of other genetically dissimilar African groups to the African-American gene pool. DRB1 allele frequencies (specifically DRB1*1501) and some haplotypes of DRB1-DPB1 were different in our NYC and the 11th International Histocompatibility Workshop (IHW) samples of African-Americans. The high level of allele and haplotype diversity found in African-Americans has important implications for the construction of pools of unrelated potential donors for tissue transplantation.

Alleles↗
PubMed1997

African-American HLA class II allele and haplotype diversity.

Molecular genetic techniques were used to type nine loci in the HLA class II region in 241 unrelated African-Americans from New York City (NYC). Several effects attributable to recent genetic admixture were evident: the number of distinct class II alleles and haplotypes was larger in the African-Americans than in people of African or European origin, the allele frequencies were more consistently even, and linkage disequilibrium was present across the entire class II region. The African-American DRB1 allele frequencies almost always fell between frequencies among samples from northern Europe and the Gambia, two possible founding populations. The exceptions are attributed to the contribution of other genetically dissimilar African groups to the African-American gene pool. DRB1 allele frequencies (specifically DRB1*1501) and some haplotypes of DRB1-DPB1 were different in our NYC and the 11th International Histocompatibility Workshop (IHW) samples of African-Americans. The high level of allele and haplotype diversity found in African-Americans has important implications for the construction of pools of unrelated potential donors for tissue transplantation.

Alleles↗
PubMed1993

HLA-DQ polymorphisms do not explain HLA class II associations with multiple sclerosis in two Canadian patient groups.

Patient sharing of HLA-DQ allelic polymorphisms is a possible explanation for the association of multiple sclerosis (MS) with different HLA class II haplotypes in different populations. We used two-locus linkage analysis to investigate the relevance of three different polymorphisms to MS susceptibility in 79 French Canadian patients and 62 mixed ethnic white patients. In French Canadians, we found that an MS association with shared DQB1 sequences and a DQA1 codon for glutamine at residue 34 is secondary to an MS association with the common DR2 haplotype, DRB1*1501-DQA1*0102-DQB1*0602. In contrast, we found that an MS association in French Canadians with a DQB1 codon for leucine at residue 26 (DQ beta Leu26) is not secondary to an MS association with the DR2-bearing haplotype. Mixed ethnic whites showed a positive MS association with the DR2 haplotype but no MS association with any of these polymorphisms. We conclude that (1) the DR2 haplotype is predispositional for MS in both populations, (2) DQ beta Leu26 is an additional predispositional factor in French Canadians, and (3) none of the DQ polymorphisms fully explains the association of MS with HLA alleles in both patient groups.

Alleles↗
PubMed1994

The reduced expression of HLA-class II antigens and adhesion molecules on monocyte surface after phagocytosis of bacteria.

The reduced expression of HLA-class II antigens (DQ and DP) and some intercellular adhesion molecules (CD11b, CD54 and CD58) was found on monocytes after phagocytosis of bacteria (S. aureus, E. coli, P. aeruginosa, S. enteritidis) but not of latex particles. In contrast, the expression of HLA-DR, CD11a and CD18 was not changed in the course of phagocytosis. The observed changes were related to the amount of phagocytosed bacteria but not to their viability or phagocytosis induced physical changes expressed as the reduction of FSC signal during flow cytometry analysis.

Animals↗
PubMed2001

Family-based association of HLA class II alleles and haplotypes with type I diabetes in Brazilians reveals some characteristics of a highly diversified population.

The association of HLA class II haplotypes with type I diabetes was analyzed in 56 Southeastern Brazilian families using affected family-based controls (AFBAC) method. DRB1-DQA1-DQB1 alleles were determined by polymerase chain reaction/sequence-specific primer genotyping. This study first revealed the great haplotype diversity of Brazilians (65 different haplotypes even with incomplete DRB1 subtyping), probably due to the admixture of Africans genes with European and Amerindian genes in this population. The results revealed increased frequencies of the DRB1*03-DQA1*0501-DQB1*02 and DRB1*0401-DQA1*03-DQB1*0302 haplotypes in the patient group The highest risk for type I diabetes was associated with the heterozygote DRB1*03/*04 genotype as largely reported, and DRB1*03/X and DRB1*04/Y genotypes conferred a significant, but much lower disease risk. Protection from type I diabetes revealed some peculiarities in Southeastern Brazilians: a lack of significant protecting effect of the DRB1*1501-DQA1*0102-DQB1*0602 haplotype, and an apparent protection conferred by the DRB1*13-DQB1*0301, DRB1*11-DQB1*0301, and DRB1*01-DQB1*0501 two-locus haplotypes. The risk to type I diabetes in the highly diversified Southeastern Brazilians evidenced specific information to the prediction of the disease in this region of the country.

Adolescent↗
PubMed1993

Genetic typing of HLA class II genes in Swedish populations: application to forensic analysis.

In an attempt to determine the value of DNA based typing of HLA class II loci to forensic analysis, allele and genotype frequencies at DQA1, DQB1, DPB1, and DRB1 were determined in samples from two Swedish populations using hybridization with sequence specific oligonucleotides to PCR amplified DNA. Significant allele frequency differences were observed at the DQB1 and DRB1 loci between the two populations, as well as between one of the Swedish and a Norwegian population. The average heterozygosity varies between 0.74 to 0.91 and the power of discrimination between 0.90 to 0.98, with the highest values obtained for the DRB1 locus. The probability of genotype identity by chance differs on average 2% between the populations. When applied to a paternity case with one parent deceased and a criminal case, typing of class II loci proved in both cases informative. Analyses of DR and DQ genes does not increase the power of discrimination, due to strong linkage, but offers through the reconstruction of putative haplotypes an internal control for the consistency of the typing results at several loci. Typing of the DRB1 and DPB1 loci was found to result in an approximate combined average probability of genotype identity by chance of one in a thousand.

Alleles↗
PubMed1993

Expression of class II HLA molecules by endothelial cells of human decidua.

Many authors have documented a high level of expression of class II HLA molecules by decidua. Although macrophages appear to be responsible for this, we show in this article that endothelial cells (EC) of the venules and capillaries of human decidua also strongly express class II molecules, whereas EC of chorionic villi do not. We discuss this finding in the context of the maternal-fetal immune interaction.

Arterioles↗
PubMed1996

HLA class II genes in chronic hepatitis C virus-infection and associated immunological disorders.

To investigate the factors that may confer susceptibility or protection to hepatitis C virus (HCV) infection and to HCV-associated immunological disorders, we designed two studies on 420 Sardinian transfusion-dependent thalassemia patients followed in our department in Cagliari since 1974. The first one was an epidemiological survey aimed to evaluate the prevalence of HCV infection and HCV-associated immunological disorders. In the second study, the distribution of different HLA class II genes was examined by DNA analysis in 116 HCV positive patients, 30 HCV negative patients, and 606 healthy controls. Three hundred fourteen patients became infected with HCV (74.7%) after 5.6 +/- 2.8 years of regular transfusion program. Mixed cryoglobulinemia, purpura, arthritis, proteinuria, decreased complement levels, rheumatoid factor and anti-GOR, smooth muscle antibody (SMA), anti-nuclear antibody (ANA), and liver, kidney microsome (LKM) autoantibodies were significantly more represented in HCV positive patients than in negative ones (P < .05). A significant increase of HLA class II DR2 subtype (DRB1*1601,DQB1*0502) was observed in a group of 30 HCV negative patients who despite 10.3 +/- 2.2 years in a regular blood transfusion program did not show any evidence of HCV infection (Pc < .0092). Our results represent clear evidence for a relationship between HCV infection and immune extrahepatic abnormalities. A gene(s) located in the human major histocompatibility complex (MHC) region may play an important role in conferring protection against HCV infection.

Adolescent↗