SEARCH · PubMed Health

Results for “Class”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 865 records · Page 48Linked to original sources

PubMed1992

High levels of linkage disequilibria between serologically defined class I bovine lymphocyte antigens (BoLA-A) and class II DQB restriction fragment length polymorphism (RFLP) in Norwegian cows.

Serum defined BoLA-A antigens, together with BoLA-DQB RFLP patterns, were determined in 87 almost unrelated Norwegian cattle. Statistical analysis revealed strong linkage disequilibria between these loci at the population level. A total of 13 haplotypes were found to be present at frequencies significantly greater than those predicted on the basis of their component gene frequencies. Among these, the subgroups 1A and 1B of the DQ1 haplotype were found to be closely associated with the class I antigens A11 and w16, respectively. The association between A11 and DQ1A is of particular interest, as two independent studies, one employing class I serology, and the other RFLP analysis of the class II locus DQ, have previously indicated that A11 and DQ1A confer relative susceptibility to mastitis.

Alleles↗

PubMed1992

Soluble HLA class I and class II concentrations in commercial immunoglobulin preparations.

Soluble HLA class I (sHLA-ABC) and class II (sHLA-RQP) molecules were quantitated in 16 commercially available immunoglobulin (Ig) preparations by enzyme-linked immunosorbent assays. Whereas three Ig preparations contained no detectable sHLA-ABC, all preparations showed concomitant sHLA-RQP molecules. There was a considerable variability with regard to the individual sHLA concentrations. For sHLA-RQP the values exceeded that found in human plasma of healthy individuals, suggesting that the extraction procedure may concentrate not only Ig, but also HLA class II molecules. Based on the total dosage of intravenously administered immunoglobulins (i.v.Ig), contaminating sHLA molecules may become immunogenic. Furthermore, sHLA molecules are discussed in terms of participation in the well-known immunomodulating effects of i.v.Ig therapy.

Enzyme-Linked Immunosorbent Assay↗

PubMed1998

HLA class I and class II DNA typing and the origin of Basques.

Seven HLA class I and class II loci (HLA-A, B, C, DRB1, DQA1, DPA1 and DPB1) were typed at the DNA level in two populations of the Iberian Peninsula (100 Basque and 88 Catalan individuals) in order to unravel their genetic relationship and to compare these results with other European and Mediterranean populations. For the first time, the frequencies of alleles and haplotypes for the class I HLA loci at the DNA level in these populations are presented. The most frequent haplotype in both populations is A*29-Cw*1601-B*44-DRB1*0701-DQA1*0201-DPA1*0103-DPB 1*0401. Neither population differed markedly from the highly homogeneous European and Mediterranean genetic landscape. The Basques, a European outlier population according to classical genetic markers, appear to lie within the genetic European variation with a slight uniqueness and show no clear relationship to North African populations, as has been postulated in some previous HLA studies. Here, the range of possibilities provided by the highly polymorphic HLA system is stressed by using genetic distances, phylogenetic trees and principal component analyses in order to reconstruct population history.

Alleles↗

PubMed1998

Soluble HLA class I and class II antigens in patients with multiple sclerosis.

Soluble HLA class I (sHLA-I) and soluble HLA class II (sHLA-II) antigen levels during different stages of disease were investigated in paired serum and cerebrospinal fluid (CSF) samples from 37 patients with multiple sclerosis (MS) using ELISA and Western blot analysis. Soluble HLA-II antigens in the serum of untreated patients with the relapsing-remitting type of MS (RRMS) were found to be significantly elevated in acute relapse as compared to values obtained from patients under steroid treatment, in remission or healthy controls. No significant differences in circulating sHLA-I levels could be detected. In contrast, a trend towards increased intrathecal production of sHLA-I molecules in the CSF was observed in untreated RRMS patients in acute relapse, whereas the levels of soluble HLA-II antigens in the CSF were below the detection limit of the ELISA method. Our observations underline the presence of systemic immune activation in MS patients, as reflected in elevated serum sHLA-II antigen levels, and reveal a dichotomy between sHLA class I and II antigen production in the peripheral blood versus CSF in acute MS. Serial measurements of sHLA-II antigen levels might represent a non-invasive method to assess disease activity in MS patients.

Enzyme-Linked Immunosorbent Assay↗

PubMedDate not supplied

Expression of a MHC non-classical class I gene, Q4, is similar to a classical class I gene, Dp.

We have investigated the effects of the cell cycle on expression of Q4 mRNA. Q4, the gene encoding the Qb-1 antigen, is transcribed in a wide variety of tissues, unlike many other non-classical class I genes. We have compared the pattern of Q4 transcription in the cell cycle to classical class I, beta-2-microglobulin and actin. We found that the pattern of Q4 RNA levels resembles that of the classical class I genes, consistent with the similarity of the 5' sequences of Q4 and K/D. Thus, Q4 mRNA accumulates during the cell cycle along with the total RNA, but does not show specific transcriptional enhancement. This is consistent with a function for Q4 similar to the classical K/D gene products.

Animals↗

PubMed1996

Investigation of the association of major histocompatibility complex genes, including HLA class I, class II and TAP genes, with clinical forms of Crohn's disease.

The aim of this study was to determine immunogenetic markers of susceptibility in Crohn's disease (CD), taking the different features of the clinical course of the disease into account. HLA class I, HLA class II and TAP transporter gene polymorphisms were studied using DNA typing methods. Gene and antigen frequencies were analysed and compared in a group of 102 CD patients and 200 unrelated healthy controls from the same area. Analysis of the whole CD patient population revealed no definite association with either HLA or TAP gene alleles, with the exception of an association with DRB1*1302 (Pc < 0.05). However, when clinical subgroups of patients were considered, specific associations with some genetic markers were found. The most definitive results involved a genetic association in the group of patients who did not respond to glucocorticoid therapy. This group was characterized by a high frequency of HLA-DRB1*04 (P < 0.05). Conversely, a positive association with the TAP2-A allele was found in cortico-responder patients (Pc < 0.03). Furthermore, analysis of the distribution of HLA class II alleles in relation to the presence of extra-intestinal manifestations revealed an association with the DQB1*0501 or *0503 suballele of DQ5 (P < 0.05). Finally, patients with lesions in the small bowel were more frequently HLA DRB1*07 (P < 0.05). The present study supports the concept of clinical heterogeneity in Crohn's disease associated with a background of genetic heterogeneity.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1991

Identification of an immunodominant epitope within the phosphoprotein of rabies virus that is recognized by both class I- and class II-restricted T cells.

Immunization of H-2k mice with live rabies virus induces cytolytic T lymphocytes to the phosphoprotein of rabies virus. The antigenic determinant responsible for stimulating this class I-restricted cytolytic response was mapped to 50 amino acids (residues 180 to 229) of the phosphoprotein by using vaccinia virus recombinants expressing either the full-length phosphoprotein or C-terminal truncations of the phosphoprotein. The epitope was more finely mapped to residues 191 to 206 by using synthetic peptides. Several CD4+, class II-restricted T-cell lines were isolated from splenocytes of H-2k mice immunized with the vaccinia virus-rabies virus phosphoprotein recombinant virus. These lines were specifically stimulated by the phosphoprotein, and in addition, each line proliferated and released lymphokines in response to the same synthetic peptide shown to stimulate phosphoprotein-specific, class I-restricted cytolytic T cells.

Amino Acid Sequence↗

PubMed2006

Loss of human leucocyte antigen class I and gain of class II expression are early events in carcinogenesis: clues from a study of Barrett's oesophagus.

BACKGROUND: Human leucocyte antigen (HLA) expression is altered in oesophageal carcinomas compared with normal tissue. It is unclear, however, whether this phenotype precedes malignant transformation or results as a consequence of it. AIM: To investigate HLA class I and II expression in Barrett's oesophagus and normal squamous oesophageal tissue. METHODS: Asian patients with Barrett's oesophagus (n = 64) and a control group (n = 60) with a normal oesophagus but without reflux symptoms were recruited using endoscopic and histopathological criteria. Tissue samples were stained with monoclonal antibodies specific for HLA-ABC, HLA-DR alpha chain or HLA-DP/DQ/DR, and scored semiquantitatively. The results of immunohistochemical staining were correlated with clinical and histopathological characteristics of patients. RESULTS: Marked expression of HLA-ABC was observed in 50% of Barrett's oesophagus sections as compared with 68.3% of controls (p = 0.038). HLA-DR staining was seen in 51.6% of Barrett's oesophagus samples versus 11.7% of controls (p<0.001). Expression of HLA-DP/DQ/DR was evident in 73.4% of oesophageal intestinal metaplasia tissue as opposed to 18.3% of controls (p<0.001). Importantly, a total loss of HLA-ABC and a concomitant gain of HLA-DP/DQ/DR expression were seen in 37.5% of patients with Barrett's oesophagus but in none of the controls (p<0.001). Interestingly, this phenotype was associated positively with dysplasia (adjusted p, p* = 0.031) but negatively with non-steroidal anti-inflammatory drug use (p* = 0.004). CONCLUSIONS: HLA class I expression is down regulated and class II expression is up regulated in Barrett's oesophagus. As these changes predate malignant transformation, altered major histocompatibility complex expression may be a key event in disease progression, possibly in facilitating evasion from immune surveillance.

Adult↗

PubMed1995

Protective effects of interferon-gamma in intraocular herpes simplex type 1 infection do not depend on major histocompatibility complex class I or class II expression.

Intraocular infection with herpes simplex virus type I strain F (HSV-1) induces bilateral retinitis, the expression of both MHC class I and II molecules and activation of CD4 and CD8 cells. To investigate the role of MHC upregulation in IFN-gamma mediated antiviral effects in intraocular infection with HSV-1, we infected MHC deficient mice and mice with an additional ectopic site of IFN-gamma production in their retina (rho gamma) intravitreally with HSV-1 into one eye. Protective effects of IFN-gamma in intraocular HSV-1 infection were notable as sparing of the contralateral non-inoculated eye from retinitis, and were not dependent on MHC class I and class II expression, thus limiting the importance of MHC expression for the outcome of viral infection in vivo.

Alleles↗

PubMed1999

Discoordinate expression of invariant chain and MHC class II genes in class II transactivator-transfected fibroblasts defective for RFX5.

MHC class II deficiency or bare lymphocyte syndrome is a severe combined immunodeficiency caused by defects in MHC-specific transcription factors. In the present study, we show that fibroblasts derived from a recently identified bare lymphocyte syndrome patient, SSI, were mutated for RFX5, one of the DNA-binding components of the RFX complex. Despite the lack of functional RFX5 and resulting MHC class II-deficient phenotype, transfection of exogenous class II transactivator (CIITA) in these fibroblasts can overcome this defect, resulting in the expression of HLA-DR, but not of DP, DQ, and invariant chain. The lack of invariant chain expression correlated with lack of CIITA-mediated transactivation of the invariant chain promoter in transient transfection assays in SSI fibroblast cells. Consequently, these CIITA transfectants lacked Ag-presenting functions.

Alleles↗

PubMed1999

Attenuation of MHC class II expression in macrophages infected with Mycobacterium bovis bacillus Calmette-Guérin involves class II transactivator and depends on the Nramp1 gene.

The natural resistance associated macrophage protein 1 (Nramp1) gene determines the ability of murine macrophages to control infection with a group of intracellular pathogens, including Salmonella typhimurium, Leishmania donovani, and Mycobacterium bovis bacillus Calmette-Guérin (BCG). The expression of the resistant allele of the Nramp1 gene in murine macrophages is associated with a more efficient expression of several macrophage activation-associated genes, including class II MHC loci. In this study, we investigated the molecular mechanisms involved in IFN-gamma-induced MHC class II expression in three types of macrophages: those expressing a wild-type allele of the Nramp1 gene (B10R and 129/Mphi), those carrying a susceptible form of the Nramp1 gene (B10S), and those derived from 129-Nramp1-knockout mice (129/Nramp1-KO). Previously, we published results showing that Ia protein expression is significantly higher in the IFN-gamma-induced B10R macrophages, compared with its susceptible counterpart. In this paper, we also show that the higher expression of Ia protein in B10R cells is associated with higher I-Abeta mRNA expression, which correlates with a higher level of IFN-gamma-induced phosphorylation of the STAT1-alpha protein and subsequently with elevated expression of class II transactivator (CIITA) mRNA, compared with B10S. Furthermore, we demonstrate that the infection of macrophages with M. bovis BCG results in a down-regulation of CIITA mRNA expression and, consequently, in the inhibition of Ia induction. Therefore, our data explain, at least in part, the molecular mechanism involved in the inhibition of I-Abeta gene expression in M. bovis BCG-infected macrophages activated with IFN-gamma.

Animals↗

PubMedDate not supplied

[Soluble HLA class I and HLA class II antigens in the blood of HIV infected patients].

The levels of HLA, class I, antigen and HLA-DR antigen in the blood sera of HIV-infected persons were determined by the enzyme immunoassay. The levels of soluble antigens HLR-DR and of HLA, class I, in serum samples containing only antibodies to HIV were elevated, respectively, 1.8- and 1.3-fold in comparison with the norm. The level of soluble HLA-DR antigen in samples containing the markers of other infections (HBsAg, antibodies to hepatitis C virus, anti-IgM antibodies to cytomegalovirus) was significantly higher in comparison with samples containing only antibodies to HIV and serum samples from healthy donors (p < 0.05). The concentration of soluble HLA antigen, class I, in the samples containing antibodies to HIV and markers of other infections was also elevated, but the statistically authentic increase in comparison with the normal level was observed only in the presence of the markers of HIV infection, hepatitis C and cytomegalovirus infection.

Cytomegalovirus Infections↗

PubMed2004

Lower incisor extraction in Class I and Class II malocclusions: case reports.

After a brief discussion of the indications/contraindications of extracting lower incisors as part of orthodontic treatment, five case reports are presented. These cases highlight that extracting lower incisors can be an accepted orthodontic option, not only in compromised class III treatments, but also in Class I and Class II malocclusions.

Adolescent↗

PubMed1990

Activation of MHC class I-restricted CD8+ CTL by microbial T cell mitogens. Dependence upon MHC class II expression of the target cells and V beta usage of the responder T cells.

The T cell response to microbial T cell mitogens (MTM) such as enterotoxins from Staphylococcus aureus (SE) and the soluble mitogen from Mycoplasma arthritidis, resemble the minor lymphocyte stimulatory locus (Mls) response in several aspects. An important feature of the Mls response is it restriction to CD4+ cells. This study demonstrates that in contrast to Mls, the MTM response includes both CD4+ and CD8+ subsets. Both CD4+ and CD8+ cells expanded in IL-2 after stimulation with SEB showed preferential expression of T cell receptors bearing V beta 8 domains. Mouse and human target cells could be lysed in the presence of MTM both by MTM-stimulated CD8+ lymphocytes and by MHC class I-restricted CTL clones of defined Ag specificity. MTM-induced lysis required the expression of MHC class II, but not class I Ag, on the target cells. Inhibition studies of SEB and Ag-dependent cytolysis by CTL clones underlined the crucial role of CD3 and LFA-1 in both instances, but showed CD8 dependence only for AG-dependent cytolysis. Together these findings suggest important differences between the putative MTM-mediated interaction of TCR with MHC molecules and the classical TCR/MHC interaction involved in MHC-restricted Ag recognition.

Animals↗

PubMed1989

[Differences of clinical and axiographic function parameters in patients with skeletal Class II and Class III anomalies].

21 young individuals with skeletal and dental class II-relationships were compared to an analogous group of class III individuals as to their mandibular range of motion. The measurements of clinical movements in pro- and laterotrusion as well as the lengths of axiographic tracings showed a significantly reduced capacity of motion in the class III group. Because all examined individuals exhibited undisturbed TMJ-function or, at most, had mild symptoms (Helkimo-indexes 0 or 1), the reported findings cannot be interpreted as signs of pathology, but seem to demonstrate the broad range of normality.

Humans↗

PubMed1989

Murine cell lines stably expressing the influenza virus hemagglutinin gene introduced by a recombinant retrovirus vector are constitutive targets for MHC class I- and class II-restricted T lymphocytes.

A retrovirus vector containing the hemagglutinin (HA) gene of influenza virus was constructed and used to infect murine cell lines of fibroblast, mastocytoma and B cell lineages which are able to present antigens to MHC-restricted T cells. Stable cell lines were selected in which the retrovirus vector integrated as a single copy in almost all of the individual cell clones examined. The HA mRNA was shown to be of the expected length by Northern blot analysis, but the levels varied among the cell clones. Although the HA transcript was difficult to detect in any of the retrovirus-infected cell clones derived from fibroblasts, HA Ag was easily detected on the cell surface by cytofluorographic analysis. Significantly, retrovirus-infected clones derived from each cell type were recognized by HA-specific class I and class II MHC-restricted T lymphocytes. HA produced in these cells was able to be acquired, processed, and presented to class II-restricted T cells by additional, non-HA-expressing APC. This indicates that HA endogenously synthesized within these cell lines is available for Ag processing by an exogenous route.

Animals↗

PubMed1998

Non-insulin-dependent diabetes mellitus in New Zealand Maori: a relationship with Class I but not Class II histocompatibility locus antigens.

AIMS: To investigate the possibility of a relationship between the major histocompatibility complex (MHC) and non-insulin-dependent diabetes mellitus (NIDDM) in Maori. Such relationships have previously been shown in non-European races with a high incidence of NIDDM. METHODS: We performed serological Class I and PCR-SSP Class II HLA typing on 44 Maori with NIDDM and renal failure and compared the results with normal Maori. RESULTS: A strong relationship with the HLA-B40 groups of antigens (relative risk 5.1 chi 2 = 16.8, p < 0.001) was found; this was mainly attributable to HLA-B48 and HLA-B60. There was no HLA Class II relationship. CONCLUSION: The relationship with HLA-B40 antigens suggests that the MHC or other genes on chromosome 6 play a role in NIDDM in Maori.

Diabetes Mellitus, Type 2↗

PubMed1998

Internalization of iscom-borne antigens and presentation under MHC class I or class II restriction.

Exogenous nonreplicating antigens (Ag) incorporated into immunostimulating complexes (iscoms) induce CTL responses under MHC class I restriction. A requirement for inducing CTL responses is that the Ag is delivered to the cytosol of antigen-presenting cells (APC), a route restricted to endogenously produced Ag. To investigate the mechanisms by which iscoms elicit MHC class I-restricted responses, the intracellular distribution of influenza virus envelope proteins incorporated in iscoms (flu-iscoms) or in micelles (flumicelles) was studied in vitro using murine peritoneal cells (PEC). Ultrathin sections of cells pulsed with biotinylated flu-iscoms or flu-micelles were analyzed by electron microscopy after detection of the biotin label by reaction with streptavidin-gold. PEC pulsed with flu-iscoms showed a pattern of scattered gold particles distributed in clear and dense vesicles as well as in the intracellular space but not associated with organelles. In cells pulsed with flu-micelles, Ag was also detected in most cellular compartments but at a considerably lower concentration. The intracellular distribution of particulate Ag in iscom or micelle form was confirmed by lysis and differential centrifugation of Ag-pulsed APC. Furthermore, P815 cells pulsed with flu-iscoms were lysed by specific immune effectors showing that the iscom-Ag was processed and presented by class I-expressing APC. Flu-iscoms were internalized about 50-fold more efficiently than ovalbumin iscoms (ovaiscoms) suggesting that the nature of the protein and/or the presence of cellular receptors are important factors influencing the capacity of APC to take up iscom-borne proteins. PEC accounted for the most active internalization of iscom-borne Ag, although splenic dendritic cells and B cells also took up fluiscoms with remarkable efficiency.

Animals↗