Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.3.1 (alkaline phosphatase)
47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mucosal immune system is concerned with host defense along the moist surfaces of the body which have contact with the external environment. These sites contain specialized lymphoid structures which contain precursors for IgA-synthesizing B lymphocytes and immunoregulatory T lymphocytes which will determine whether oral tolerance or a strong immune response develops against antigens administered orally. The key step to antigen processing in the gastrointestinal tract involves its initial uptake from the gut lumen by specialized follicle associated epithelium called 'M' cells. M cells originate from adjacent crypt epithelium and are interspersed between the absorptive epithelial cells in the follicle-associated epithelium. M cells cells have short, irregular microvilli, are closely associated with lymphocytes, do not have a prominent terminal web, and have only weak alkaline phosphatase activity but strong nonspecific esterase activity. M cells do not express surface MHC class II (HLA-DR) antigens. These cells take up macromolecules, viruses, bacteria and protozoa within 30 minutes from the initial presentation of the antigen to the intestinal lumen. After the initial uptake of antigen by M cells, the antigens are transported into the follicular areas to be processed by dendritic cells and brought into close contact with the antigen-specific precursors for IgA secreting plasma cells. The final result of M cell processing is the production of a vigorous secretory IgA response and local cell-mediated immunity with suppression of a systemic IgG, IgE and delayed-type hypersensitivity to orally-administered antigens.
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PMID:Antigen processing in the mucosal immune system. 139 96

Proximal tubular (PT) epithelial cells express MHC class II (Ia) antigens in immunologically-mediated renal injury. To study the role of PT as accessory cells, we generated several murine PT-like epithelial cell lines by transformation with origin-defective SV40 DNA. These transformed cell lines display typical alkaline phosphatase and gamma-glutamyl-transpeptidase enzyme activity, proliferation to epidermal growth factor (EGF) and sodium-dependent glucose uptake. Clonal lines of transformed tubular cells from both normal C3H/FeJ and autoimmune MRL-lpr mice do not constitutively express Ia antigens or mRNA for class II. However, stimulation with recombinant interferon-gamma(rIFN-gamma) induces Ia mRNA and surface product in the cell lines. These Ia-positive cells can process and present hen egg-white lysozyme (HEL) to antigen-specific Iak-restricted T cell hybrids. Unstimulated tubular cells do not express detectable IL-1 alpha, IL-1 beta, TNA-alpha, or IL-6 mRNA. However, stimulation with IL-1 alpha or LPS induces TNF-alpha transcripts. We conclude that these cell lines have characteristics most consistent with a proximal tubular origin. They also bear characteristics of accessory cells such as processing and presentation of antigen and TNF-alpha gene expression. We speculate that PT have the capacity to participate in the pathogenesis of immune renal injury.
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PMID:MHC class II, antigen presentation and tumor necrosis factor in renal tubular epithelial cells. 240 90

Human Peyers patches (PP) were studied by immunohistochemistry to characterize functional properties of the follicle-associated epithelium (FAE) including the "membrane" (M) cells. The FAE had no transporting capacity for polymeric IgA (pIgA) because it did not express the secretory component (SC) which acts as a pIgA receptor. However, it expressed MHC class II (HLA-DR) determinants, except for the M cells (which were tentatively identified by absence of brush border alkaline phosphatase). It is possible, therefore, that the FAE generally performs class II-restricted transport and presentation to T cells of antigens which have been adequately processed in the gut lumen. The function of M cells may be limited to transport of particulate or undegraded antigens to subjacent macrophages for processing and subsequent presentation. There were significantly more intra- and subepithelial T cells in PP than in distant villi, and the T cells were concentrated adjacent to M cells. The proportion of the CD4+ phenotype (putative helper T cells) was much higher in FAE (approximately 40%) than in villous epithelium where the CD8+ (putative suppressor) phenotype predominated strikingly (approximately 90%). This disparity might reflect differences in capacity for positive and negative immune regulation at the two sites. The B cells terminating with Ig production in PP and adjacent to solitary lymphoid follicles apparently belonged to relatively mature memory clones as they showed a large proportion of IgG immunocytes and reduced J-chain expression. Conversely, both IgG and IgA immunocytes in lamina propria (LP) showed a high percentage of J-chain positivity (80-100%); such positivity was also considerable (45-60%) in mesenteric lymph nodes (MLN) in contrast to peripheral lymph nodes (PLN) and palatine tonsils (PT). Moreover, there was a decreasing percentage of IgA2 immunocytes in the order of PP (52%), distant ileal LP (40%), MLN (32%), PLN (11%), and PT (5%). Taken together, our results suggested that dissemination of relatively immature memory B-cell clones with high J-chain expression takes place from PP through MLN and that preferential settlement of such clones occurs in LP.
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PMID:Human Peyer's patches: lympho-epithelial relationships and characteristics of immunoglobulin-producing cells. 249 34

Recently, great interest has been shown in the histological identification of small cell tumours of childhood--nephroblastoma (Wilms' tumour), neuroblastoma, rhabdomyosarcoma and Ewing's sarcoma--using immunohistochemical methods. However, several antigens operationally specific for leucocyte typing in blood and marrow are also expressed on cells of epithelial and neural origin. We undertook phenotypic characterization of 17 non-haemopoietic small cell tumours of childhood using a panel of 30 monoclonal antibodies to leucocyte, epithelial and cytoskeletal antigens using a sensitive alkaline phosphatase-anti-alkaline phosphatase technique on cryostat sections of fresh tumour. Our results demonstrated frequent expression of the leucocyte-associated antigens CD10 (CALLA), CD9 (p24) and CDw32 (FcRII) in these small cell tumours and occasional expression of MHC class II (HLA-DR) and HNK-1 antigens. However, the leucocyte-associated antigens CD45 (leucocyte common), CD22 (pan B-cell), CD11b (C3bi receptor), CD15 (Lewisx) or CDw42 (platelet gp Ib) were not detected on any tumour. Aberrant expression of desmin, neurofilament and UJ13A antigen was found in nephroblastoma and of epithelial-associated markers (CIBr17 and 43-9F) in neuroblastoma. Our results also demonstrated broad reactivity in frozen section with two monoclonal antibodies specific for melanoma (NKI/C-3) or epithelial cells (OM-1) in paraffin sections. Hence, it is necessary to include monoclonal antibodies to CD45 and pan-epithelial antigens, e.g. LP34 (cytokeratin) or HEA125 for the precise immunohistochemical identification of small round cell malignancies of childhood.
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PMID:Phenotypic characterization of non-haemopoietic small cell tumours of childhood with monoclonal antibodies to leucocytes, epithelial cells and cytoskeletal proteins. 254

Follicle-associated epithelium (FAE) of normal human Peyer's patches (PP) was studied with regard to expression of HLA-DR determinants and secretory component (SC); the latter acts as a receptor for polymeric immunoglobulins (pIg). Putative M cells were identified in FAE by lack of a brush border with alkaline phosphatase. These cells were virtually negative for HLA-DR whereas the remaining FAE was strongly positive like villous epithelium. Conversely, the complete FAE showed no SC expression and was negative for IgA. These findings suggested that the FAE (including the M cells) does not participate in SC-mediated transport of pIgA, which in the gut mainly takes place through columnar crypt cells. The FAE (excepting the M cells) may be involved in an MHC class II-restricted antigen-presenting function as recently suggested for villous epithelium. The role of M cells may hence be limited to uptake and transport of luminal antigens.
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PMID:Lack of relation between expression of HLA-DR and secretory component (SC) in follicle-associated epithelium of human Peyer's patches. 328 2

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.
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PMID:pH dependent binding of high and low affinity myelin basic protein peptides to purified HLA-DR2. 754 90

During a systematic cell surface antigen expression profile analysis of 76 primary childhood brain tumors (34 medulloblastomas/primitive neuroectodermal tumors and 42 astrocytomas), we employed the following library of monoclonal antibodies (MoABs): anti-Leu-2/a; anti-Leu-3/a; anti-Leu-M5; anti-Leu-11b; anti-HLA-A, -B, -C; anti-HLA-DR; anti-HLe-1 (leukocyte common antigen); and UJ 308. The MoABs identified the expression of various leukocyte-associated, lymphocyte cell line differentiated, cell surface antigens in childhood brain tumors. The antigens were detected with an indirect, biotin-streptavidin-conjugated alkaline phosphatase (AP) immunocytochemical technique. Leu-2/a+ cells comprise the significant CD8+ cytotoxic T-lymphocyte (CTL) population of the tumor-infiltrating lymphocytes. CTLs are major histocompatibility complex (MHC) class I restricted, tumor-associated antigen-specific, cytotoxic cells and were identified in 58 of 76 (76.32%) brain tumors. CTLs usually represented 1-10% of all cells, but in some cases 30-44% of the cells were CD8+. CD4+, MHC class II restricted helper lymphocytes, detected with MoAB anti-Leu-3/a, were present in 65 of 76 (85.53%) brain tumors. Usually 1-10% of the observed cells reacted with MoAB anti-Leu 3/a. Macrophages (Leu-M5 antigen-positive cells) were expressed in 74 of 76 (97.37%) brain tumors. Their number also represented 1-10% of all observed cells in the frozen brain tumor sections. All 76 (100%) brain tumors contained cells that reacted positively with MoABs anti-HLA-A, -B, -C and anti-HLA-DR, demonstrating a strong MHC class I restriction of the tumor cell population and an overall leukocyte antigen expression.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Immunophenotypic characterization of infiltrating polynuclear and mononuclear cells in childhood brain tumors. 761 61

Major histocompatibility (MHC) class II antigens are heterodimeric cell surface glycoproteins consisting of an alpha and a beta chain. Although one-dimensional SDS-polyacrylamide gel electrophoresis analysis of purified MHC class II antigens shows a single diffuse band for each chain, multiple spots of identical molecular size were observed for each chain when analyzed by two-dimensional electrophoresis. The basis of this heterogeneity has not been clearly defined and has been predicted partially to be due to glycosylation and/or phosphorylation of the mature protein. To investigate the role of the three N-linked oligosaccharides of the alpha and beta chains in determining the isoelectric point of each chain, affinity-purified MHC class II antigens from human and rat sources were deglycosylated using asparagine amidase. The complete enzymatic removal of all three N-linked oligosaccharides was confirmed by SDS-polyacrylamide gel electrophoresis as well as by four different lectin-linked Western blot analyses. Two-dimensional gel analysis of the deglycosylated molecules shows no significant difference from the fully glycosylated chains. We have expressed truncated forms of the HLA DR2 chains which lack the transmembrane and cytoplasmically exposed regions in Escherichia coli. Two-dimensional electrophoresis of these single chains also reveal multiple banding patterns. The two-dimensional banding patterns described are unaffected by exposure to acidic or basic conditions, increased gel running time in the first dimension, treatment of the proteins with alkaline phosphatase to remove any potential phosphorylation, or preincubation in the presence of iodoacetamide. Multiple forms of recombinant alpha and beta chains were also observed in Tris-glycine-urea gels which merged into a single band in the presence of SDS. In addition, partially fractionated bands from preparative isoelectric focusing gels, when refocused, showed an identical number of multiple spots spanning the same range of isoelectric points. These results together suggest that each polypeptide chain of MHC class II antigens may exist in multiconformational forms, and the observed charge heterogeneity is independent of glycosylation and phosphorylation of the proteins.
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PMID:Intramolecular charge heterogeneity in purified major histocompatibility class II alpha and beta polypeptide chains. 814 5

Fifteen sural nerve biopsies of vasculitic neuropathies have been compared with 11 cases of different non-vasculitic neuropathies and normal nerves from brain-dead organ donors. The APAAP (alkaline phosphatase monoclonal anti-alkaline phosphatase) immunostaining method was applied to cryostat sections from unfixed snap-frozen tissue samples. Immunoglobulins IgG, IgM, IgA, complement factors and light chains were reactive in biopsies of normal nerves as well as of vasculitic and nonvasculitic neuropathies. A strong reaction against IgE in the epineurial vessel walls was only seen in cases of Churg-Strauss-vasculitis. Antibodies against MHC class II (HLA DR) were positive in most of vasculitic infiltrates. Vascular endothelial cells were positive with anti MHC class I in all biopsies. A typical finding in all vasculitic neuropathies was the infiltration of epineurial vessels with CD4 positive and, to a lesser extent, CD8 positive lymphocytes. CD22 positive lymphocytes (B cells) have only been seen in about one third of vasculitic neuropathies. CD16 positive cells (NK-cells or neutrophils) could be demonstrated only in two biopsies. CD68 positive cells (macrophages) are frequently seen in most cases of neuropathy regardless of their etiology. The results support the concept of a primary T-cell mediated process against epineurial vessels as the most important mechanism in the pathogenesis of vasculitic neuropathies. In some cases with small epineurial infiltrates the vasculitic process can only be recognized with antibodies against CD4 or CD8. Therefore, the immunohistochemical evaluation of sural nerve biopsies may be helpful for identifying cases with microvasculitis.
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PMID:Immunohistochemical findings in vasculitic neuropathies. 850 63

There are several double immunolabelling methods but each has its drawbacks. More often than not, antibodies with the required specificities are available in only one species and their use normally produces false labels due to cross-reactivity. We describe a new and reliable technique for staining with primary antibodies from the same species, that can even be employed on tissues of the donor species. The protocol avoids cross-reactivities without loss in sensitivity, uses commercially available reagents and takes advantage of enzymatic detection, although it can be adapted for fluorescent labelling. Briefly, tissue is incubated with one primary antibody, followed by a peroxidase-coupled secondary antibody which is detected using amino ethyl carbazol to give a red reaction product. Meanwhile, the next primary antibody is coupled in vitro to a biotinylated secondary antibody and excess binding sites quenched with normal immune serum from the same species as the primary antibody. This complex is applied to tissue and detected by the avidin-biotin/alkaline phosphatase technique using naphthol-AS-MX-phosphate/Fast Blue BB to produce a blue label. In addition to extensive controls, the reliability and broad applicability of this method has been confirmed in (1) murine skin cryostat sections to co-visualize antigen-presenting cells (MHC class II-immunoreactive; "-ir') with either antigen detecting T lymphocytes (CD4-ir) or Langerhans cells (NLDC-145-ir) and (2) locust (Insecta) abdominal ganglion paraffin sections, where it is known that immunoreactivities for octopamine and a FMRFamide-related peptide are colocalized in only one, uniquely identifiable neuron.
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PMID:A new method for double immunolabelling with primary antibodies from identical species. 862 60


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