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Biomedical subjects

E Ulvestad

Publications and source records attributed to E Ulvestad.

At least 73 records · Page 4Linked to original sources
PubMed1994

Expression and function of CD59 on colonic adenocarcinoma cells.

The expression and function of CD59, a 19-25 kDa membrane glycoprotein that inhibits formation of the membrane attack complex of complement, was analyzed on normal and malignant human colonic epithelial cells. Analysis by immunofluorescence demonstrated a weak apical expression of CD59 on normal intestinal epithelium, with an increased expression on adenocarcinoma cells. The expression of CD59 was greatest on tumor cells with poor differentiation. The functional activity of CD59 on human adenocarcinoma cells was investigated using the colonic adenocarcinoma cell line HT29. CD59 on HT29 cells was glycosyl-phosphatidylinositol-linked, and had a molecular mass of 19-25 kDa. HT29 cells expressed approximately four times more CD59 than leukocytes, and showed a high resistance to antibody-dependent complement-mediated lysis. Blocking of CD59 with divalent antigen-binding F(ab')2 fragments of the anti-CD59 monoclonal antibody 1F5 resulted in a dose-dependent increase in complement-mediated lysis, suggesting that CD59 may be of importance in protecting colonic adenocarcinoma cells against complement-mediated cytolysis.

Adenocarcinoma↗
PubMed1994

B7/BB-1 antigen expression on adult human microglia studied in vitro and in situ.

In this study, we have examined the expression and function of B7/BB-1 on individual glial cells, by utilizing surgically resected adult human central nervous system (CNS) tissues, tissues derived from fetal human CNS, and pathology material from cases of multiple sclerosis (MS). Immunofluorescence analysis using enriched adult human derived cultures of microglia and oligodendrocytes, and mixed microglia/astrocyte cultures, demonstrated that B7/BB-1 was expressed on microglia. Adult human-derived oligodendrocytes and astrocytes, and human fetal astrocytes were B7/BB-1 negative under all culture conditions. Flow cytometry studies demonstrated a low basal level of B7/BB-1 expression on microglia that was up-regulated following incubation with interferon-gamma (IFN-gamma). Co-culture of purified fresh allogeneic CD4+ T cells with microglia for 24 h resulted in clustering of T cells around microglia and microglial B7/BB-1 expression. Preincubation of microglia with an anti BB-1 monoclonal antibody (mAb) prior to microglia: CD4+ T cell co-cultures resulted in partial inhibition of the ability of microglia both to present recall antigen to autologous CD4+ T cells and to present antigen to allogeneic CD4+ T cells in primary mixed lymphocyte reaction (1 degree MLR). The CTLA-4 Ig fusion protein inhibited the ability of microglia to present antigen in both antigen presentation assays to an even greater extent than did the anti BB-1 mAb. The BB-1 antibody also inhibited the ability of microglia to stimulate previously activated T cells in a secondary 2 degrees MLR. In sections of multiple sclerosis brain, B7/BB-1 expression was observed on activated microglia in select parenchymal lesions, and on perivascular cells and infiltrating monocytes. B7/BB-1 immunoreactivity was not found in normal appearing white matter from MS brain or from non-inflammatory brain specimens. Our results indicate that the B7/BB-1 molecule plays a functional role in the capacity of microglia to serve as CNS antigen-presenting cells that can both initiate and perpetuate CD4+ T cell activation.

Abatacept↗
PubMed1994

Human microglial cells have phenotypic and functional characteristics in common with both macrophages and dendritic antigen-presenting cells.

Resting microglia comprise up to 13% of the cells in human central nervous system (CNS) white matter. Their large number and dendritic morphology make them ideally suited to survey the CNS for noxious stimuli. Upon activation microglia gradually lose dendritic processes and transform into typical phagocytic macrophages. Microglia have been implicated as the main antigen presenting cell within the CNS, and appear to be of central importance as effectors and regulators of demyelination. To further characterize the capacity for immune reactivity within the human CNS, we have studied several characteristics of microglia, both in situ and in vitro. We find that human microglia have ultrastructural, phenotypic (CD11c, CD68, acid phosphatase), and functional (FcR and CR mediated phagocytosis) properties typical for cells of the monocyte lineage. Our data indicate that microglia also have properties in common with dendritic antigen-presenting cells. Electron microscopy studies show extended dendritic cell processes on cultured microglia, and microglia are, like dendritic cells, negative for the monocyte markers nonspecific esterase, endogenous peroxidase, CD14, and RFD7. Microglia constitutively express HLA-DR in situ, and express the dendritic cell marker RFD1 upon activation. Coculturing of microglia with CD4+ T cells results in clustering of T cells around microglia and initiation of a mixed lymphocyte reaction, both distinguishing features of dendritic cells. These functional properties of microglia may be of importance for the maintenance of an immunologic response in the CNS, an organ where dendritic cells, in contrast to other organs, have not previously been identified.

Adult↗
PubMed1994

Reactive microglia in multiple sclerosis lesions have an increased expression of receptors for the Fc part of IgG.

Receptors for the Fc part of IgG, FcRI (CD64), FcRII (CD32), and FcRIII (CD16) were studied by indirect immunoperoxidase staining of cryostat sections from normal and multiple sclerosis (MS) brains. Microglia in the parenchyma of normal white matter had a dendritic morphology, and were weakly stained by monoclonal antibodies (mAbs) to FcRI, FcRII, and FcRIII. In active MS lesions reactive microglia were strongly stained by the mAbs 32.2 (FcRI), IV-3 (FcRII), and 3G8 (FcRIII). Perivascular macrophages were stained by all anti-FcR mAbs in both normal white matter and in MS lesions, whereas endothelial cells were stained by the anti-FcRIII mAb only. The FcR on microglia and perivascular macrophages may be of functional importance in antibody-dependent cell-mediated cytotoxicity (ADCC), phagocytosis, and local immunoregulation. FcR on endothelium may be of importance in binding and transportation of immune complexes into the CNS. FcR mediated functions may consequently be highly relevant to the pathogenesis of MS.

Adult↗
PubMed1994

Fc receptor for IgG (FcR) on rat microglia.

Receptor for IgG (FcR) was demonstrated on rat microglia in vivo and in vitro by immunohistochemical staining with immune complexes of horseradish peroxidase (HRP) and rabbit IgG anti-HRP. Astrocytes, oligodendrocytes and neurons did not express FcR. Microglia in culture also showed FcR-mediated agglutination and phagocytosis of IgG-sensitized erythrocytes. A radiolabelled cDNA probe for rat FcRIII hybridized with a 1.4-kb RNA band in Northern blots prepared from total RNA from rat brain. FcRIII mRNA-positive cells in rat brain, presumably microglia, were demonstrated by in situ hybridization. FcR participates in the initiation of cytotoxic responses and of phagocytosis by microglia and is therefore likely to be important in mediating immune reactions in the brain.

Animals↗
PubMed1994

Immune regulatory and effector properties of human adult microglia studies in vitro and in situ.

Monocytes, macrophages, and brain microglia are the primary cell types most readily demonstrated to be infected in CNS lesions of patients infected with HIV (Koenig et al., 1986). Microglia are implicated in mediating CNS immune regulation and neural tissue injury associated with the AIDS-dementia syndrome. This report describes the isolation and characterization of microglia from the adult human central nervous system (CNS), and the assessment of microglial immune accessory/effector functions, some of which might be altered in CNS infectious and autoimmune diseases. In our studies we have compared the in vitro properties of microglia with peripheral blood monocytes/macrophages, and with astrocytes, a CNS cell type also implicated in contributing to immune regulatory and effector functions. Additionally, we have compared phenotypic features of resident microglia in situ with monocytes and macrophages that have infiltrated the CNS during the course of CNS inflammation. Our results suggest that adult human derived parenchymal microglia represent a unique cell of monocytic origin that can be distinguished both in vitro and in situ from monocytes/macrophages recently infiltrating into the CNS and from perivascular macrophages/microglial cells. Our data demonstrate that parenchymal microglia express several immune accessory/adhesion molecules that can provide second signals for CD4+T cell stimulation. Furthermore, microglia can synthesize cytokines and reactive oxygen species that may augment ongoing pathology in the CNS of AIDS patients. Infection of resident brain microglia could augment microglial immune accessory/effector functions possibly contributing to pathology seen in HIV dementia.

Adult↗
PubMed1994

Fc receptors for IgG on cultured human microglia mediate cytotoxicity and phagocytosis of antibody-coated targets.

We have utilized surgically resected human central nervous system (CNS) tissue to determine the expression and functions of Fc receptors (Fc gamma R) on individual cell types found within the CNS. We observed all three classes of Fc gamma R on microglial cells in situ and in vitro, but not on astrocytes or oligodendrocytes. Incubation of cultured microglia with immune complexes (antibody-coated red blood cells) induced phagocytosis, antibody-dependent cell-mediated cytotoxicity (ADCC), and oxidative bursts. We also found that microglia have the capability to produce T cell stimulatory soluble mediators after Fc gamma R crosslinking. These functional responses were enhanced by pretreatment of the microglia with interferon-gamma (IFN-gamma). Our results implicate microglial effector responses triggered by interaction of Fc gamma R with opsonized antigens as potential mediators of tissue injury within the CNS. Such injury may be particularly applicable to multiple sclerosis, an inflammatory demyelinating disease characterized by intrathecal production of immunoglobulins and cytokines.

Adult↗
PubMed1994

Phenotypic differences between human monocytes/macrophages and microglial cells studied in situ and in vitro.

This report describes a phenotypic differentiation pattern conceived to distinguish invading monocytes from resident microglia in frozen and formalin-fixed human CNS. Phagocytic cells in normal and diseased CNS (multiple sclerosis and encephalitis) were studied immunohistochemically with a panel of antibodies, and phenotypic characteristics were compared with cultured monocytes/macrophages and microglia. Monocytes/macrophages were positive for the markers non-specific esterase, myeloperoxidase, L1, lysozyme, RFD7, and CD14, whereas microglia were negative for the same markers. Both populations of cells were positive for CD11c and CD68. Our results indicate that invading monocytes/macrophages mainly have a perivascular location in active multiple sclerosis lesions, whereas invading monocytes/macrophages also infiltrate the parenchyma in acute inflammatory CNS diseases such as in encephalitis.

Acute Disease↗
PubMed1994

Fc gamma-receptor activity of placental annexin II.

We have previously produced a MoAb, B1D6, against a placental FcR. The antigen isolated using F(ab')2-fragments of B1D6 exhibits Fc-binding properties with low affinity for IgG. The antigen is a single-chained glycoprotein with a molecular weight of approximately 37 kDa and a pI of about 7.0-8.5. Amino acid sequences from enzymatic digests of the antigen indicated that it is annexin II. Immunoreactivity using anti-annexin antisera and purified placental annexin II have further established the specificity of B1D6 to annexin II. The B1D6 epitope appears to be intramembraneous and intracellular on placental syncytiotrophoblasts, monocytes and other cells investigated.

Amino Acid Sequence↗
PubMed1994

Effects of human calprotectin (L1) on in vitro immunoglobulin synthesis.

Calprotectin (L1) is a major cytoplasmic protein of neutrophilic granulocytes and monocytes/macrophages which is released from leucocytes during activation or cell death. Apart from in vitro antimicrobial and antiproliferative activity little is known about the biological function of the protein. Since previous investigations have shown that calprotectin plasma levels are elevated in various inflammatory rheumatic diseases, we wanted to investigate if calprotectin has an effect on immune cell functions. Peripheral blood mononuclear cells, either unstimulated or polyclonally stimulated with mitogen, were incubated with calprotectin and effects were assessed by enumeration of immunoglobulin secreting cells (ELISPOT). The results indicate that incubation with high concentrations of calprotectin (> 64 micrograms/ml) inhibit the production of the three classes of immunoglobulins investigated (IgG, IgM and IgA), both for mitogen stimulated and unstimulated lymphocytes. Except for the highest concentration of calprotectin (500 micrograms/ml), it seems plausible that the observed inhibitory effect of calprotectin on Ig production is not a result of a direct toxic effect of calprotection on B lymphocytes. Altogether, these effects of high calprotectin levels might be of importance in the immunoregulation of inflammatory conditions.

Adult↗
PubMed1994

Nitric oxide synthase in human placenta.

Nitric oxide synthase is demonstrated immunohistochemically in the cytosol, on granules, and on syncytiotrophoblasts membranes. The enzyme is also detected on placental villous stroma cells, and on endothelial cells. The histochemical staining method NADPH-diaphorase stains the syncytiotrophoblasts intensely, and stroma cells more weakly. Membranes of syncytiotrophoblasts immobilized on nitrocellulose paper are also stained by NADPH-diaphorase, and by antisera to nitric oxide synthase. Oxidases of sex steroid synthesis do, however, influence placental trophoblasts and there are discrepancies in the staining pattern of endothelial cells. Caution should therefore be exercised when using NADPH-diaphorase as a staining method for nitric oxide synthase in placenta.

Amino Acid Oxidoreductases↗
PubMed1994

Identification of a soluble Fc gamma-binding molecule (annexin II) in human serum using a competitive ELISA.

We have previously produced a monoclonal antibody (mAb), B1D6, reactive with a 37 kD placental IgG Fc-binding molecule (FcR), recently identified as annexin II. Annexin II is an intracellular molecule found in several cell types, including endothelium and monocytes. Since soluble Fc-binding molecules are of importance in the regulation of the immune response, we have now used B1D6 in a competitive ELISA to study levels of soluble annexin II in human sera. Soluble annexin II was detected in all sera studied. The highest levels were observed in patients with infectious mononucleosis. Gel filtration of sera revealed annexin II in fractions corresponding to a molecular weight of 40-60 kD. In Western blot analysis a molecule of approximately 37 kD was found. The pI of soluble annexin II was about 7.5-8 as demonstrated by chromatofocusing. Annexin II belongs to a family of phospholipid-binding molecules involved in anti-inflammatory responses, and elevated levels of annexin II in serum may be important for the suppression of an immune response.

Annexin A2↗
PubMed1994

The expression of CD59 in normal human nervous tissue.

The expression of CD59, a complement regulator of the formation and function of the terminal cytolytic membrane attack complex, was studied in human normal nervous tissue by immunohistochemical markers using two monoclonal antibodies 1F5 and MEM43. CD59 was present on Schwann cells, neurons and endothelial cells in the peripheral nervous system (PNS), and on Schwann cells in culture. In the central nervous system (CNS) CD59 was found predominantly on endothelial cells. There was also a diffuse staining of white and grey matter of the spinal cord and brain, presumably of microglia, oligodendrocytes, astrocytes and neurons, as these cells were CD59 positive in culture. Furthermore, CD59 was detected in the cerebrospinal fluid (CSF) of healthy individuals. CD59 in the PNS and CNS was glycosyl-phosphatidylinositol linked and had a molecular weight of 19,000-25,000. The presence of CD59 on various cells of the nervous system and in the CSF suggests that regulation of complement activation by this protein is important in neural host defence mechanisms.

Adult↗
PubMed1994

Immunology of multiple sclerosis.

Multiple sclerosis (MS), a putative autoimmune disease of unknown etiology, is characterized by CNS perivascular inflammation, foci of demyelination, and elevated intrathecal production of oligoclonal IgG's. T and B cells, macrophages, and microglia are all implicated in contributing to the initiation and perpetuation of the disease. In this brief review we discuss the possible role of T cells, B cells, macrophages, and microglia in contributing to the initiation and perpetuation of inflammation and demyelination in MS. Data from the rodent model of MS, experimental allergic encephalomyelitis (EAE) supporting a immunological basis for the pathology of MS is noted. This paper discusses recent data suggesting an interaction of the above-mentioned cells, as well as serum and CSF proteins including complement and anti-myelin/oligodendrocyte antibodies, in the pathogenesis of MS and EAE. Additionally, this review describes each cell type including the clinical and experimental evidence for their contribution to the immunologically mediated pathology of MS. Following the description of the role of individual cells, there is consideration of: the possible interaction of cells with the blood brain barrier (BBB) under normal and pathologic inflammatory conditions; the traffic of cells into the CNS in inflammation; and the role of antigen presentation within the CNS in the initiation, and perpetuation, of the CNS immune response. Finally, the review suggests a role for T cells in the initiation, amplification, and possibly the termination of CNS inflammatory events with particular attention paid to the pattern of T cell activation and T cell cytokine production.

Animals↗
PubMed1994

HLA class II molecules (HLA-DR, -DP, -DQ) on cells in the human CNS studied in situ and in vitro.

Human leucocyte antigen (HLA) class II molecules expressed by antigen-presenting cells (APC) are major restriction elements in the interaction between APC and T cells of the CD4+ subtype. To explore the immune accessory function of cells in the central nervous system (CNS), we studied the expression of HLA-DR, -DP, and -DQ molecules on CNS cells in situ and in vitro. Reactive microglia and perivascular cells in multiple sclerosis lesions expressed all three HLA class II molecules, whereas microglia in the normal CNS expressed HLA-DR only. All three HLA class II molecules were up-regulated on cultured microglia after stimulation with interferon-gamma (IFN-gamma). Microglial stimulation of allogeneic CD4+ T cells in a mixed lymphocyte reaction (MLR) was effectively blocked using anti-HLA-DR monoclonal antibodies (mAb) but not using anti-HLA-DQ mAb. HLA class II-positive astrocytes and endothelial cells were not identified in normal or diseased CNS. Cultured astrocytes stimulated with IFN-gamma could, however, be induced to express HLA class II antigens of all subtypes, although great variability was observed between different donors. Our results indicate that although both microglia and astrocytes are capable of expressing all HLA class II subtypes in vitro, subtype expression differs between normal and pathological states in situ. Such selective expression may be associated with functional properties.

Adult↗
PubMed1993

Induction of primary T cell responses by human glial cells.

Glial cells of the central nervous system (CNS) are postulated to function as immune accessory cells which may regulate immune reactivity occurring within the CNS, activating or alternatively inhibiting T cell responses. We have utilized surgically resected cerebral tissue derived from young adult humans to prepare dissociated cultures of glial cells (mixed astrocyte-microglia-oligodendrocyte cultures) and demonstrate that such cells are capable of acting as stimulators of primary T cell responses, using proliferation of T cells to allogeneic determinants on the glial cells as the test system. Studies of resected adult cerebral tissue indicated major histocompatibility complex (MHC) class II antigen expression on microglia in situ. Using a mixed lymphocyte reaction (MLR), we observed that enriched microglial cultures alone were capable of stimulating primary responses of freshly isolated T cells or the CD4+ T cell subset, a response which could be inhibited with an anti-MHC class II blocking antibody. In agreement with previous studies using rodent-derived astrocytes, we found that human astrocytes (fetal), could not initiate a primary T cell response even after up-regulation of MHC class II antigen expression with interferon gamma (IFN gamma) and tumor necrosis factor alpha (TNF alpha). Our results indicate that a primary T cell response, as well as a secondary response to a recall antigen, can occur within the CNS; our data implicate microglia as the central cell involved in the former.

Adolescent↗