Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “HLA class II”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 19 recordsLinked to original sources
PubMed1990

Invariant chain trimers are sequestered in the rough endoplasmic reticulum in the absence of association with HLA class II antigens.

HLA class II antigens are heterodimeric cell surface glycoproteins that interact with antigenic peptides to form complexes recognizable by CD4-positive T cells. During their biosynthesis, class II antigens are retained in a post-Golgi compartment in association with the invariant chain, which dissociates before class II cell surface expression. To address whether the invariant chain mediates this post-Golgi retention, its transport and assembly were examined in cells that do not express HLA class II antigens. Pulse-chase analysis and endoglycosidase digestions showed that very little invariant chain proceeded as far as the trans-Golgi in class II-negative cell lines. Immunofluorescence studies suggested that in these cells the invariant chain is sequestered in the RER. Gel filtration and cross-linking data showed that RER-localized invariant chain is present as trimers or aggregated trimers. Multimerization is mediated by lumenal interactions; a proteolytic fragment of the invariant chain corresponding to the lumenal domain remained trimeric as determined by cross-linking analysis. Similar transport and structural characteristics were observed for a pool of excess invariant chain in class II-positive cells, suggesting that an excess of invariant chain in the ER may be important for class II antigen function. These results have important implications for the transport of cellular proteins in general and for the role of the invariant chain in class II antigen biosynthesis.

B-Lymphocytes↗
PubMed1990

A new approach for the analysis of HLA class II polymorphism: 'HLA oligotyping'.

Histocompatibility typing allows the matching of patients and donors in organ transplantation, and the accuracy of HLA matching influences to a great extent the clinical outcome. Recent breakthroughs in the molecular biology of HLA class II genes have revealed that the degree of HLA diversity and polymorphism is in fact much greater than was expected on the basis of the traditional serological HLA typing assays. In parallel, it has become possible to analyse this extensive polymorphism directly at the level of the HLA class II genes and of their DNA sequences. We have described a DNA typing procedure referred to as 'HLA oligotyping' which is based on the hybridisation of allele and loci specific oligonucleotide probes. This procedure has now become operational on a large scale and this review describes the principles and major applications of the technique. It consists in the hybridisation of DNA with informative sequence-specific oligonucleotide probes, following an amplification of DNA in vitro by the polymerase chain reaction (PCR). The use of this highly sensitive technique for HLA-DR, -DQ and -DP typing is discussed, focusing on the clinical applications in the field of organ transplantation, particularly for bone marrow transplantation with unrelated donors. It now allows the unambiguous identification of all HLA subtypes, including those that cannot be recognised otherwise, and it represents powerful complement to current methods of HLA typing. Finally this methodology is widely used in HLA-disease association studies, aiming at the characterisation of HLA class II epitopes involved in the susceptibility or resistance to autoimmune diseases.

Antigen-Presenting Cells↗
PubMed1991

De novo HLA class II and enhanced HLA class I molecule expression in SV40 transfected human thyroid epithelial cells.

Human thyroid follicular cells normally synthesize and express HLA Class I molecules but in glands affected by autoimmune or neoplastic diseases they express Class II molecules. We have investigated the effect of SV40 virus transformation on the expression of MHC molecules in human thyrocytes. Primary cultures of human thyroid from two different glands were transfected with the plasmid pX-8, containing the 'early' region of SV40 virus, and two continuous lines of thyrocytes were obtained. The cell lines maintained features of parental thyroid epithelial cells showing the characteristic cytokeratin filament network, microvillar protrusion and tight junctions. In addition, the SV40-transfected cells responded to graded doses of TSH with increased c-AMP production. Thyrocytes from both cell lines hyperexpressed Class I molecules and a significant proportion of them also acquired constitutive Class II expression, as determined by indirect immunofluorescence (IFL), flow cytometry and Northern blotting hybridization using a DR beta probe. These cells were found to be normally up-regulated by interferon (IFN)-gamma. Indirect IFL and flow cytometry analysis were used to detect and quantify the expression of HLA-DR, DP and DQ subregions. A co-ordinated expression (DR greater than DP much greater than DQ), reminiscent of the inappropriate HLA expression found in thyroid autoimmune disease in vivo and of the in vitro regulation in normal thyrocytes, was observed. Clones derived from these cell lines differed in their level of constitutive Class II expression and in their sensitivity to Class II induction by IFN-gamma. In conclusion, these thyroid cell lines could provide a useful tool for further investigation of HLA gene regulation in thyroid cells and for elucidating on the mechanism involved in the inappropriate HLA expression described in autoimmune and neoplastic diseases of the thyroid.

Autoantigens↗
PubMed1984

Generation and characterization of murine monoclonal antibodies against HLA Class II molecules.

HLA Class II antigens (human la) are coded by Major Histocompatibility Complex and play important biological roles in health and disease. In this report we describe the generation and characterization of nine murine monoclonal antibodies (MoAbs) specific for determinants localized on the human la molecules. The reactivity of these MoAbs inferred from serological analysis along with the data obtained from biochemical characterization of the target structures allowed a classification of these reagents as monomorphic and polymorphic. Two monomorphic MoAbs, identifying different subsets of human la molecules, were studied in detail.

Animals↗
PubMed1986

Construction of chain- and locus-specific HLA class II DNA probes. Study of HLA-class II transcripts in leukemias.

In addition to their role in the immune response, MHC class II antigens may be considered as differentiation markers on hemopoietic cells. To study expression of class II genes at the mRNA level in leukemias representing various stages of lymphoid and myeloid differentiation, we constructed chain- and locus-specific HLA class II DNA probes. As the genes encoding the DR, DQ, and DP beta-chains display a strong sequence homology in the second extracellular and transmembrane domains, we used probes derived from the less conserved 3' untranslated regions. For the more divergent alpha-chain genes, DNA fragments derived from the coding portion were obtained from cDNA clones. All probes were designed to minimize background due to AT- or GC-rich segments and subcloned into pUC plasmids. Their lack of cross-hybridization was demonstrated in Southern blot experiments under moderately stringent conditions. Northern blot analysis of RNA from 15 patients with acute lymphoblastic and myeloblastic leukemias, chronic lymphoid and hairy cell leukemias showed that most patients expressed variable amounts of class II transcripts, some lacked all class II mRNA, and only two patients had a dissociated expression of class II genes, with lack of DQ and presence of DR and DP mRNA. This study reveals a vast heterogeneity of MHC class II gene expression in leukemias, as previously demonstrated at the protein level. The availability of these highly specific DNA probes should prove useful in extensive studies directed at better defining HLA class II gene expression during hemopoietic differentiation in physiologic and pathologic states.

Actins↗
PubMed1984

Measles virus-specific T4+ human cytotoxic T cell clones are restricted by class II HLA antigens.

We have generated measles virus-specific T cell clones from a patient with multiple sclerosis who has been described previously as a strong responder to measles virus. T cell clones were screened on the basis of their capacity to proliferate to measles virus. The cell surface phenotype of each clone was OKT3+, OKT4+, OKT8-. The majority of these clones (11 of 14) were cytotoxic for their autologous measles virus-infected lymphoblastoid B cell target. This cytotoxicity was specific for measles virus inasmuch as these T cell clones could not lyse influenza or mumps virus-infected B cell targets. By using a panel of HLA-defined measles virus-infected B cell lines, these clones were shown to recognize measles virus in the context of HLA class II determinants. A monoclonal antibody that recognizes HLA class II monomorphic determinants (L243), but not a monoclonal antibody that recognizes HLA class I antigens (W6/32), inhibited the lysis of the autologous measles virus-infected B cell target by these T cell clones. These results demonstrate that these cytotoxic T cell clones specific for measles virus are HLA class II restricted.

Clone Cells↗
PubMedDate not supplied

Induction of HLA class II antigens in osteosarcoma cells by interferons and tumor necrosis factor alpha.

In this study we have evaluated the ability of interferons (IFNs) alpha, beta, gamma and Tumor Necrosis Factor (TNF) alpha to modulate the expression of the Major Histocompatibility Complex (MHC) antigens in human osteosarcoma cells. The osteosarcoma cell lines Saos-2 and U-2 OS, treated in vitro with IFNs and TNF alpha, showed an increased expression of class I HLA antigens. However, only IFN gamma and, to a lower extent, IFN beta induced the expression of class II HLA antigens. These effects were dose and time-dependent. Simultaneous treatment with IFN gamma and IFN beta or TNF alpha, which by itself was unable to induce the expression of class II HLA antigens, produced different effects on the two osteosarcoma cell lines: in Saos-2 IFN beta and TNF alpha amplified the effects obtained with IFN gamma alone; in U-2 OS, TNF alpha increased the expression induced by IFN gamma on class II HLA antigens, whereas IFN beta antagonized the effects of IFN gamma. IFN alpha did not influence the induction of class II HLA antigens by IFN gamma in the two osteosarcoma cell lines. IFNs have been introduced in some clinical protocols for the treatment of osteosarcoma, based on their antiproliferative activity. Our findings may contribute to a better knowledge of the effects of IFNs and TNF alpha in osteosarcoma by showing the existence of more complex interactions.

Cell Division↗
PubMed1985

Evidence for the role of class I and class II HLA antigens in the lytic function of a cloned line of human natural killer cells.

Monoclonal antibodies with specificity for HLA class I and class II antigens were generated which either inhibit or enhance the lytic activity of a cloned line of human NK cells. These antibodies were obtained from a fusion with spleen cells from mice immunized with NK clone 3.3. They affect the lytic function of that clone at the level of the killer cell; additional evidence suggests that the effect takes place during an early stage of lysis. Immunoprecipitation and cross-clearing experiments using MHC antibodies of known specificity demonstrate the reactivity of mAbs 131 and 164 with HLA class I antigens and mAbs 210 and 273 with HLA class II antigens. Binding studies indicate that these antibodies are probably recognizing nonpolymorphic MHC determinants. Although these antibodies bind to other NK effector cells tested, they have no effect on the lytic function of these bulk NK populations. Preliminary studies, however, indicate that they do affect the NK activity of a proportion of the clones within these bulk populations. To further assess the potential role of HLA gene products in the lytic function of NK3.3, several well-defined anti-MHC antibodies were tested for their effects on NK3.3 function. The anti-HLA class I and class II antibodies could each be grouped into functional categories based on their ability to enhance, inhibit, or not affect the lysis of NK-sensitive targets K562 and MOLT-4 by NK clone 3.3. These results demonstrate, for the first time, a potential involvement of MHC molecules with NK function.

Animals↗
PubMed1990

HLA class II genes: typing by DNA analysis.

A detailed understanding of the structure and function of the human major histocompatibility complex (MHC) has ensued from studies by molecular biologist during the last decade. Virtually all of the HLA genes have now been cloned, and the nucleotide sequences of their different allelic forms have been determined. Typing for these HLA alleles is a fundamental prerequisite for tissue matching in allogeneic organ transplantation. Until very recently, typing procedures have been dominated by serological and cellular methods. The availability of cloned DNA from HLA genes has now permitted the technique of restriction fragment length polymorphism (RFLP) analysis to be applied, with remarkable success and advantage, to phenotyping of both HLA Class I and Class II determinants. For the HLA Class II genes DR and DQ, a simple two-stage RFLP analysis permits the accurate identification of all specificities defined by serology, and of many which are defined by cellular typing. At the present time, however, RFLP typing of HLA Class I genes is not as practicable or as informative as that for HLA Class II genes. The present clinical applications of HLA-DR and DQ RFLP typing are predominantly in phenotyping of living donors, including selection of HLA-matched volunteer bone marrow donors, in allograft survival studies, and in studies of HLA Class II-associated diseases. However, the time taken to perform RFLP analysis precludes its use for the typing of cadaveric kidney donors. Nucleotide sequence data for the alleles of HLA Class II genes have now permitted the development of allele-specific oligonucleotide (ASO) typing, a second category of DNA analysis. This has been greatly facilitated by the ability to amplify specific HLA Class II DNA 'target' sequences using the polymerase chain reaction (PCR) technique. The accuracy of DNA typing techniques should ensure that this methodology will eventually replace conventional HLA phenotyping.

DNA↗
PubMed1988

Molecular studies of a rare DR2/LD-5a/DQw3 HLA class II haplotype. Multiple genetic mechanisms in the generation of polymorphic HLA class II genes.

A cDNA library was constructed from a homozygous B lymphoblastoid cell line (REM) obtained from an individual of a long isolated American Indian tribe, the Warao. The REM cell line expresses serologically defined determinants, DR2 and DQw3, and the T lymphocyte-defined (Dw/LD) specificity, LD-5a. T cells can recognize differences between FJO (a DR2/DQw1 cell line that expresses the Dw specificity MN2) and REM for both DR and DQ molecules. cNDA clones encoding the polymorphic DR beta 1-, DR beta 2-, DQ beta-, and DQ alpha-chains were sequenced and compared with other DR and DQ gene sequences. The DR beta 1-sequence of REM is identical to the DR beta 1-sequence of FJO; the DR beta 2-sequence is also identical to that of FJO except for one amino acid difference at position 67 in the polymorphic first domain (Leu in REM, Phe in FJO) due to a single point mutation. The DQ beta-sequence is identical to that of DR4/DQw3 haplotype; the DQ alpha is different from the DQ alpha of DR4/DQw3 haplotype and identical to the DQ alpha of both the DR3/DQw2 haplotype of a Raji cell line and the DR5/DQw3 haplotype in deduced amino acid sequence. Taken together, these findings suggest that: 1) a single amino acid difference (position 67) in the third hypervariable region of the first domain of the DR beta 2-chain in the DR2 haplotype is apparently sufficient for stimulating T cell responses; 2) the DQw3 serologic specificity may be defined mainly by the DQ beta-rather than DQ alpha-chain; and 3) multiple genetic events have probably occurred to generate the rarely found REM (DR2/LD-5a/DQw3) haplotype.

Amino Acid Sequence↗
PubMed1990

Cytokine-mediated modulation of HLA-class II, ICAM-1, LFA-3 and tumor-associated antigen profile of melanoma cells. Comparison with anti-proliferative activity by rIL1-beta, rTNF-alpha, rIFN-gamma, rIL4 and their combinations.

Nine different human melanomas and 16 clones, isolated from 2 of them, were characterized for susceptibility to rIL1-beta-, rIL4-, rTNF-alpha- and rIFN-gamma-mediated effects on proliferation and surface expression of class-II HLA (DR and DP), ICAM-1 and LFA-3 molecules and of 3 tumor-associated antigens (recognized by MAb 763.74T, 149.53 and R24). In spite of marked inter- and intra-tumor heterogeneity for susceptibility to the effects of each cytokine, the most frequent upregulation was induced on the HLA class-II antigens by rIFN-gamma and on adhesion molecules by rIFN-gamma, rTNF-alpha and rIL1-beta, while tumor-associated antigens were often down-modulated by rIFN-gamma. Tumor heterogeneity was also evident on tumor-cell proliferation with an apparent hierarchy in the frequency and extent of inhibitory effects: rIFN-gamma greater than rTNF-alpha greater than rIL1-beta = rIL4. Combinations of 2 cytokines resulted in rare and limited changes in the antigenic profile in comparison to the effects seen with single factors, while the combination of rTNF-alpha and rIFN-gamma resulted in significant synergistic antiproliferative effects on most tumor cells and clones. Taken together, these results indicate that single cytokines can profoundly affect the antigenic profile of melanoma cells, while strong tumor-growth inhibition is often achieved by combinations of 2 cytokines acting in synergism.

Antigens, Neoplasm↗
PubMed1989

[Recent aspects of the pathogenesis of endocrine autoimmune diseases in the human: what role does expression of class II HLA molecules in the endocrine target cell play?].

The inappropriate expression of HLA Class II molecules by the target cells of endocrine autoimmune diseases is a recent observation that has been intensively studied in thyroid autoimmunity and type I diabetes mellitus. In vitro studies have shown that interferon-gamma can induce Class II expression, either alone, as in thyrocytes, or in combination with other mediators like tumour necrosis factor or lymphotoxin, as in islet cells, pointing to possible mechanisms operating in vivo. Endocrine cells expressing Class II molecules are able to present their autoantigens to helper T cells, thus possibly inducing the autoimmune process. However, until now it is still unclear if the expression of Class II molecules by the target cells is the primary immune phenomenon, which might possibly be triggered by a latent viral infection of the endocrine cell. Alternatively, it might be a secondary response in an ongoing autoimmune process. Particularly data obtained in the diabetic pancreas favour the first possibility, but only progress in our understanding of the role of HLA antigens in immunoregulation will make it possible to interpret the phenomenon properly.

Autoimmune Diseases↗
PubMed1987

Precise specificity of induced tubular HLA-class II antigens in renal allografts.

HLA-class II antigen expression is induced in the tubules of renal allografts, but it is unclear whether all three class II products--HLA-DR, DQ, and DP--are induced, and whether the induced product is of donor origin. A pretransplant (n = 14) and serial transplant biopsies (n = 45) were obtained from 14 transplant recipients in whom induced HLA-class II antigen was detected after transplantation with a monoclonal antibody reactive with HLA-DR, DP, and possibly DQ antigens. Cryostat sections were stained with locus-specific or polymorphic monoclonal antibodies in an indirect immunoperoxidase assay. In pretransplant biopsies intracellular HLA-DR antigen was expressed on proximal tubules, whereas all tubules were negative for HLA-DQ and DP products. After transplantation grafts with induced tubular HLA-class II antigen had induced HLA-DR, DQ and DP antigens expressed both within the cytoplasm and on the cell membranes. The donor or recipient origin of induced HLA-class II expression was determined using polymorphic antibodies specific for either donor or recipient antigens. This approach demonstrated that the induced class II antigen is of donor origin--and, furthermore, that the renal parenchyma remains of donor HLA-type, even one year after transplantation, and thus remains a source of antigenic stimulus to the recipient.

Antibodies, Monoclonal↗
PubMed1983

Involvement of class II HLA molecules in T cell activation by antigen. Implications for the autologous mixed lymphocyte reaction.

Our recent studies on the involvement of HLA Class II molecules in T cell activation by antigen are briefly reviewed. Both DR and MT Class II molecules were found to be able to function as restriction elements. The allotypic parts of DR molecules appeared to be most important in this respect, and were also found to influence the spectrum of antigen-specific responses. Both blood derived monocytes and Langherhans' dendritic cells were able to function as antigen-presenting cells, and expressed the same restriction elements. The relevance of these findings for the autologous mixed lymphocyte reaction (AMLR) is briefly discussed.

Antigen-Presenting Cells↗
PubMed1986

Cell mediated PPD specific cytotoxicity against human monocyte targets: III. Cellular typing with CTLs restricted by class II HLA antigens.

The HLA-restriction specificity of a set of Cytotoxic T-Lymphocytes (CTLs) derived from 20 different individuals and with specificity for antigenic components in Purified Protein Derivative of tuberculin (PPD) were examined against a panel of 50 unrelated target cell donors. PPD pulsed monocytes were used as antigen presenting target cells. CTLs were generated by Interleukin-2 (IL-2) expansion of in vitro PPD activated Peripheral Blood Mononuclear Cells (PBM). The results confirm our previous finding that PPD-specific CTLs are restricted by HLA-class II - and not by class I antigens. The 20 CTLs used together provide reliable cellular typing reagents for the antigens HLA-DR2, -3, -4 and -7 and less so for the antigens HLA-DR1 and -5. In contrast, sharing between CTL- and target cell donors of HLA-DRw6 and -w8 correlates poorly to PPD-specific cytotoxicity. A few consistent exceptional patterns were observed. In one case lack of lysis in spite of HLA-DR antigen sharing could be explained by a split of HLA-DR2 into a normal and a short variant. Positive reactions in combinations, where no HLA-DR antigens are shared, were only few and evenly distributed among CTLs. Thus our findings indicate that our bulk CTLs predominantly contain clones restricted by determinants strongly associated to the serologically defined HLA-DR antigens.

Antigens, Surface↗
PubMed1986

Dissection of HLA class II haplotypes in HLA-DR4 homozygous individuals.

In order to identify better markers for HLA-DR4-associated autoimmune disorders, we have studied the complexity of the HLA class II region in DR4-positive cells at the DNA level and compared the DNA polymorphism with that defined by serology, mixed lymphocyte culture (MLC) reactivity, and protein chemistry. At the DNA level, HLA-DR4 can be characterized by a homogeneous pattern of bands hybridizing to HLA class II cDNA probes. Besides, subtypes can be defined within DR4 using HLA-DR beta, -DQ alpha, and -DQ beta cDNA probes in Southern blot analysis. Three subtypes are found using the DR beta cDNA probe. One of these subtypes correlates with the cellularly defined Dw15 specificity, another with the serologically defined LB4 and LB14 specificities. None of the restriction fragment length polymorphism (RFLP) patterns coincide with the MLC-defined DR4 subtypes Dw4, Dw10, Dw13, and Dw14 separately. Variation of two fragments hybridizing to the DQ alpha cDNA probe obtained after either Pvu II or Taq I digestion yields three subtypes. Pvu II- and Eco RI-digested DR4 DNA give rise to three DQ beta detectable subtypes. Correlation between these subtypes, isoelectric point variation of DQ molecules, and the DQ-related allelic system TA10/2B3 are demonstrated. Some of the patterns obtained with DQ alpha and DQ beta cDNA probes display heterozygosity in the DQ region, as demonstrated by family segregation. No correlation was observed between DQ and the cellularly defined Dw determinants. A new polymorphism has been obtained with the DQ alpha probe, probably due to DX polymorphism. DR beta RFLP divides the LB14 supertypic specificity into two new subtypes. A combination of the four different techniques applied to a panel of 16 DR4 homozygous cell lines reveals at least nine different haplotypes in DR4. These newly defined haplotypes may be of help in further studies concerning the relationship of micropolymorphism with several diseases.

Cell Line↗
PubMed1984

Possible involvement of the T4 molecule in T cell recognition of class II HLA antigens. Evidence from studies of CTL-target cell binding.

The present study examines the potential role of the T4 molecule in functional cell-cell interactions between target cells and human cytotoxic T lymphocyte (CTL) clones that are specific for HLA class II alloantigens encoded by the SB locus. There were marked differences (greater than 30-fold) between the seven SB-specific clones studied with respect to their susceptibility to inhibition by anti-T4 as well as anti-T3 antibodies. We wished to test the hypothesis that such variation among the clones would be due to differences in clonal "affinity" for antigen. To quantitate differences among the CTL clones in the tightness with which they bind target cells, the clones were analyzed using a previously published assay of susceptibility of CTL-target cell conjugates to dissociation in the presence of unlabeled targets. The results revealed that the clones that were most susceptible to inhibition by anti-T4 and anti-T3 were the weakest target cell binders, and vice versa. Anti-T4 antibody could partially induce dissociation of functional CTL-target cell conjugates in the absence of any added cold targets. For the "highest affinity" clone such anti-T4 antibody-induced dissociation could be observed at 4 degrees C but not 23 degrees C. These results indicate that the T4 molecule is functionally involved in target cell binding by CTL, and raise the possibility that although it is easiest to demonstrate the function of the T4 molecule in "low affinity" clones, that function may also be operative in the "high affinity" clones.

Adult↗