Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A detailed description is presented of immunohistochemical methods for identification of various types of immune effector cells in rat heart, involving the use of antibodies conjugated with different fluorochromes for the simultaneous demonstration of 2 or 3 different antigens by means of fluorescence microscopy. The initial results of the application of these techniques to the study of the myocarditis induced by interleukin-2 (IL-2) are also presented. Antibodies used included: OX6 antibody (for MHC class II molecules, mainly expressed by dendritic cells): W3/25 and OX8 antibody, for the demonstration of the rat equivalents of CD5 and CD8, respectively: asialo-GM1 ganglioside antibody for the identification of natural killer (NK) cells and lymphokine activated killer (LAK) cells, and ED2 antibody for labeling of macrophages. Fluorochromes used were: fluorescein isothiocyanate (green), tetramethylrhodamine isothiocyanate (red), Texas red sulfonyl chloride (red), and 7-amino-4-methylcoumarin-3-acetic acid (blue). IL-2-induced myocarditis was characterized histologically by infiltration of the myocardium by mononuclear inflammatory cells, microvascular alteration, interstitial edema, and myocyte damage and necrosis. In the initial stages, NK/LAK cells were the predominant type of infiltrating lymphocytes; however, the numbers of these cells decreased sharply in subsequent stages. Macrophages also were initially abundant, and continued to be prevalent throughout the late stages. CD8+ lymphocytes were more numerous than CD4+ lymphocytes. Dendritic-cells showed a diffuse increase in number and also accumulated around foci of myocyte necrosis. Three phenotypes of dendritic cells were recognized, and the possible implications of these findings are discussed. It is hoped that these techniques will prove useful for the immunohistochemical evaluation of various inflammatory diseases of the heart.
J Mol Cell Cardiol 1995 Jan
PMID:Immunofluorescence techniques for the identification of immune effector cells in rat heart: applications to the study of the myocarditis induced by interleukin-2. 753 83

Major histocompatibility complex (MHC) class II molecules are cell surface glycoproteins and are known to display processed antigens on the surface of antigen presenting cells (APC). Within the APC, the loading of processed antigenic peptides to MHC class II molecules is known to take place in the endosomal compartment at acidic pH environment. The present study describes the in vitro effect of pH on binding of four biotinylated myelin basic protein (MBP) peptides to affinity purified HLA-DR2 containing a mixture of DRB1*1501 and DRB5*0101 beta chain. The binding affinity of the selected peptides are in the order of MBP(83-102)Y83 > MBP(124-143) > MBP(143-168) > MBP(1-14). Most of these peptides in association with HLA-DR2 are considered as immunodominant epitopes for human multiple sclerosis autoimmune disorder. One epitope, MBP(1-14), had almost no affinity to purified HLA-DR2 and was used as a control peptide in all binding assays. The quantitation of the bound peptide at various pH was carried out by antibody capture of complexes followed by avidin-alkaline phosphatase detection system. Among four peptides tested, only the highest affinity MBP(83-102)Y83 peptide showed maximum binding to purified HLA-DR2 at acidic pH. Two other epitopes, MBP(124-143) and MBP(143-168), showed maximum binding at basic and neutral pH values, respectively. The binding of only high affinity peptides, MBP(83-102)Y83 and MBP(124-143), was significantly affected by changing the pH of the binding buffer. Such alteration in pH of the binding buffer resulted in 100% occupancy of DR2 with both high affinity MBP peptides. In contrast, no significant increase in binding of the low affinity MBP(143-168) peptide was observed at altered pH values. The specificity of the increased binding of high affinity peptides to HLA-DR2 at optimum pH was demonstrated by competitive binding assays using non-biotinylated peptides. Finally, the stability of various MBP peptide bound complexes was tested at 4 degrees, 25 degrees and 37 degrees C which correlates well with their affinity to HLA-DR2. These results suggest that pH plays an important role in in vitro binding of antigenic peptides and such manipulation of binding conditions can be utilized in generating 100% loaded MHC class II with high affinity antigenic peptides. Since high affinity peptides are generally considered as major immunodominant epitopes, the in vitro pH dependent binding can be utilized in screening immunodominant epitopes of various autoantigens and generating complexes of defined composition.
Mol Immunol 1995 Jun
PMID:pH dependent binding of high and low affinity myelin basic protein peptides to purified HLA-DR2. 754 90

The recent discovery of two proteasome homologous genes, LMP2 and LMP7, in the class II region of the human MHC, has implicated this multi-subunit protease in an early step of the immune response; the degradation of intracellular and viral proteins. Short peptides produced by the proteasome are transported into the ER by the product of another set of MHC class II genes, TAP1 and TAP2, where they bind and stabilise HLA class I molecules. Antigenic peptides displayed at the cell surface by HLA class I molecules mark cells for destruction by cytotoxic T lymphocytes. The role of the proteasome in antigen processing was questioned when mutant cells, which lack the LMP genes, were able to process and present antigens normally. The discovery that two proteasome beta-subunits, delta and MB1, highly homologous to LMP2 and LMP7 and expressed in reciprocal manner, is now consistent with a role for the proteasome in antigen processing. The incorporation of different beta-subunits into the proteasome may be a mechanism to modulate catalytic activity of the proteasome complex, allowing production of peptides that are more suitable to enter into the ER by the TAP transporters and to bind HLA class I molecules. But, in the absence of the LMPs, the other subunits permit processing of most antigens reasonably efficiently.
Mol Biol Rep 1995
PMID:Proteasome and class I antigen processing and presentation. 756 65

The invariant chain (Ii, CD74) is a transmembrane glycoprotein that is transiently associated with the MHC class II antigens in the endoplasmic reticulum and in endocytic vesicles. An activator of protein kinase C (PKC), 12-O-tetradecanoyl-1,2-phorbol 13-acetate (TPA), was found to enhance expression of Ii mRNA in the murine B lymphoma cell line, A20, 6-48 hr following treatment. In contrast, TPA did not induce the Ii in NIH 3T3 fibroblasts. TPA addition to either cell line activated PKC. Pretreatment of A20 cells with the PKC inhibitors, staurosporine or chelerythrine chloride, for 5 or 20 min prior to addition of TPA, decreased Ii mRNA levels when compared to cells treated with TPA alone. A 20 min preincubation with the highly specific PKC inhibitor, calphostin C, completely blocked the TPA enhanced expression of the Ii suggesting that activation of PKC was responsible for TPA increased Ii mRNA levels. IFN-gamma also blocked the TPA increased Ii mRNA levels. Constitutive expression of Ii mRNA was decreased by treatment with staurosporine but not chelerythrine chloride or calphostin C, suggesting that non-PKC protein kinases may also be important for maintaining high levels of Ii mRNA in these cells. Western blot analysis using PKC isotype specific antibodies showed that A20 cells express PKC delta abundantly whereas NIH 3T3 cells express primarily PKC alpha. These data suggest that a PKC delta mediated signal transduction pathway plays a crucial role in up-regulation of the Ii.
Mol Immunol 1995 Jun
PMID:Invariant chain (CD74) gene regulation: enhanced expression associated with activation of protein kinase C delta in a murine B lymphoma cell line. 764 56

We have attempted to elucidate the relative orientation of the T-cell receptor (TCR) to the major histocompatibility complex (MHC)-antigen complex during antigen recognition, using the T-cell response to B10.A (I-Ek) and B10.A(5R) (I-Eb) mice to the 1-23(H) peptide derived from glycoprotein D of the herpes simplex virus. The 1-23(H)-specific T-cells derived from both B10.A and B10.A(5R) mice use the same set of V alpha genes and a different array of V beta genes. The CDR1s of these TCR beta chains share residues at particular positions. The CDR2s of the TCR beta chains have a negative charge, which correlates with I-Eb reactivity and with the positively charged polymorphic residues residing at the C-terminal end of the alpha-helix of the I-Eb beta chain of the class II molecule. Taken together, the data suggest that the TCR beta chain interacts with both the alpha and beta chains of the MHC class II molecule, as does the TCR alpha chain.
Mol Immunol 1995 Jun
PMID:An alternative view of T-cell receptor-MHC interaction: T-cell receptor binds transversally to the alpha-helices of the MHC molecule. 764 58

In this article, we have summarized current facts, models and views of the autoimmunity that leads to destruction of insulin-producing beta-cells and consequent Type 1 (insulin-dependent) diabetes mellitus. The presence of strong susceptibility and resistance gene loci distinguishes this condition from other autoimmune disorders, but environmental disease factors must conspire to produce disease. The mapping of most of the genetic risk (or disease resistance) to specific alleles in the major histocompatibility locus (MHC class II) has direct functional implications for our understanding of autoimmunity in diabetes and directly implies that presentation of a likely narrow set of peptides is critical to the development of diabetic autoimmunity. While many core scientific questions remain to be answered, current insight into the disease process is beginning to have direct clinical impact with concerted efforts towards disease prevention or intervention by immunological means. In this process, identification of the critical antigenic epitopes recognized by diabetes-associated T cells has achieved highest priority.
Mol Aspects Med 1995
PMID:Self and non-self antigen in diabetic autoimmunity: molecules and mechanisms. 765 21

The MHC class II molecules bind antigenic peptides and present them to T cells. Their ability to carry out these functions depends, in a critical way, on the detailed structure of the membrane-distal alpha 1 and beta 1 domains of these molecules. Using the I-Ak molecule and a series of hen egg lysozyme (HEL) peptide-specific, I-Ak-restricted T cell hybridomas as a model, we have examined the effect of altering essentially all of the polymorphic residues of the murine class II molecule on its ability to present Ag. Our results support the following conclusions: (1) both the location and the structural alteration introduced in a specific amino acid interchange are important in determining the effect the interchange will have on Ag presentation; and (2) changes in amino acids in the floor of the putative Ag binding cleft of the class II molecule can exert a major influence on the presentation of peptides to T cells. By carrying out direct binding experiments between the HEL(46-61) peptide and two mutant I-A molecules that fail to present HEL(46-61) to appropriate T cells, we were able to assess, in a quantitative fashion, the role played by peptide binding in the failure to present Ag. Our results suggest that, in the two cases studied, the failure to bind the HEL(46-61) peptide was not primarily responsible for the failure of the mutant class II molecule to present that peptide. Specifically, an A beta chain mutant that possesses d allelic residues at positions 65-67 in the second PMR of the Ak beta chain actually binds HEL(46-61) at wild type (I-Ak) levels. In contrast, an A alpha chain chimera in which b allelic residues are inserted in the third PMR of the Ak alpha chain, binds HEL(46-61) about three- to four-fold less well than wild type. While this decrease in binding affinity may be partially responsible for the inability of the latter chimeric molecule to present HEL(46-61), it can not be the total explanation because increasing the peptide concn even by an order of magnitude does not restore Ag presentation by APC expressing this chimeric molecule. These results are discussed in terms of the currently accepted model of the class II molecule.
Mol Immunol 1993 Apr
PMID:Functional analysis of the antigen binding region of an MHC class II molecule. 768 33

The binding sites of class II major histocompatibility complex (MHC) molecules can accommodate many seemingly diverse peptides. In the case of mouse class II molecules, it appears that in general, the I-A and I-E isotypes associate with different peptides. In this study we report an example where a single amino acid substitution in an I-Ak restricted peptide changes the restriction element to I-Ek. A T cell hybridoma, F6.A10, specific for the peptide 93-104 from mouse testicular cytochrome c (Mt cyt 93-104) was found to be restricted by I-Ak using class II molecule specific blocking monoclonal antibodies (mAb). The activation of this hybridoma by Mt cyt 93-104 was competitively inhibited by other peptides that bind to the I-Ak molecule but not by the peptide Mt cyt 93-104(A96) in which lysine at position 96 was substituted by alanine. This single amino acid substitution resulted in the ability of Mt cyt 93-104(A96) to activate the pigeon cytochrome c specific, I-Ek restricted, T cell hybridoma 2B4.11. The activation of 2B4.11 by Mt cyt 93-104(A96) was inhibited by peptides which bind to the I-Ek molecule but not by Mt cyt 93-104 and by mAb specific for I-Ek but not by mAb specific for I-Ak. These results suggest that the amino acid at position 96 may be an important anchor residue for both I-Ak and I-Ek binding but that peptides with different amino acid side chains are accommodated at that position by one or the other MHC class II isotype. Thus, in this particular case a single amino acid residue in the peptides determines the MHC class II isotype specificity.
Mol Immunol 1993 Apr
PMID:A single amino acid substitution in a cytochrome c T cell stimulatory peptide changes the MHC restriction element from one isotype (I-Ak) to another (I-Ek). 768 49

The elucidation of the enzymatic processing mechanism associated with the formation of antigenic peptide fragments that combine with MHC class II molecules is fundamental to our understanding of the immune system. We have investigated a structurally well defined protein, recombinant human growth hormone (rhGH), as an antigen, and present data supporting the hypothesis that the enzyme cathepsin B can produce peptide fragments bearing T cell epitopes associated with lymphocyte proliferative response to hGH in Balb/c (H-2dhaplotype) mice. Minimal T cell epitopes are not generated; rather the cathepsin cleavage sites flank the three antigenic peptide regions, amino acid residues 31-41, 81-100, and 166-181.
Mol Immunol 1993 Apr
PMID:Evidence supporting a role for cathepsin B in the generation of T cell antigenic epitopes of human growth hormone. 768 51

Plasma membrane (PM) expression of major histocompatibility complex (MHC) class II molecule is required for the interaction of antigen (Ag) presenting cells and T lymphocytes. Class II molecules composed of an alpha and a beta chain are highly polymorphic which facilitates their interaction with Ag and Ag-specific T cells. Recently, we have focused on the less polymorphic sequences of class II molecules, the transmembrane (TM) and cytoplasmic (Cy) domains, in an attempt to understand what their function might be. Using site-directed mutagenesis to create truncations in the TM and Cy domains of IAk's alpha or beta chain, or both, we have identified some of the sequence requirements for efficient surface expression of I-Ak molecules. Ak beta TM mutants that are not expressed at the PM are not transported past the medial-Golgi as indicated by in situ staining and Western blot analysis of endoglycosidase-H-treated immunoprecipitates. The lack of transport of TM class II mutants is not due to lack of association with the invariant chain (Ii). Class II molecules with Cy domain truncations in both chains are not efficiently transported to the PM and also have a percentage of molecules that are endoglycosidase-H sensitive. In situ staining of class II in cells expressing Cy domain truncated class II molecules revealed a discrete vesicular pattern compared to the staining of transfectants that expressed wildtype class II molecules. The immunofluorescence data along with the endoglycosidase-H data indicate the Cy domains are required for efficient transport. Immunoprecipitation studies using a panel of I-Ak conformation-specific antibodies revealed that the truncation of the Cy domains of both chains did not effect the conformation of class II. However, further truncation of the Ak beta chain into the TM domain resulted in lack of transport past the ER/medial-Golgi and diminished expression (stability) of mutant class II proteins within the cells. The alpha/beta chains of the TM mutants that did associate bound a panel of conformation sensitive antibodies except for one, 3F12. We conclude that the Cy domain of the alpha and beta chains of MHC class II, as well as sequences in the TM domains of the Ak beta chain are required for efficient class II PM expression. The reason for the lack of PM expression of TM mutants may be the inability to assess a transport competent conformation as defined by the 3F12-specific epitope, while truncation of the Ak alpha Cy domains is proposed to prevent complete masking of the ER retention sequence of the Ii chain.
Mol Immunol 1995 Apr
PMID:Truncated MHC class II cytoplasmic and transmembrane domains: effect on plasma membrane expression. 775 52


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