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E K Kristoffersen

Publications and source records attributed to E K Kristoffersen.

30 records · Page 2Linked to original sources
PubMed1994

A dot-immunobinding assay for the demonstration of soluble Fc gamma receptors.

We have developed a sensitive dot-immunobinding assay to demonstrate and characterize the functional activity of soluble Fc gamma receptors (FcR). Samples containing soluble FcR were immobilized on a nitrocellulose membrane. Immune complexes of horseradish peroxidase and rabbit IgG antibodies to horseradish peroxidase (HRP) were allowed to react with nitrocellulose-bound FcR, and the immune complexes were visualized by HRP developer. The intensity of the grey dots reflected the amount of immune complex bound. Binding of immune complexes to placental extract containing soluble FcR was inhibited completely by IgG and Fc fragments, but not by F(ab')2 fragments, IgA and IgM. The method was used to characterize the subclass specificity of solubilized placental FcR. Human Fc fragments, and intact IgG1 and IgG3 proteins inhibited the binding whereas preparations of F(ab')2, IgG2 and IgG4 did not. In conclusion, the dot-immunobinding assay described is a rapid and simple method for the demonstration and characterization of functionally active soluble FcR.

Antigen-Antibody Complex↗
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

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↗
PubMed1991

IgG Fc receptor heterogeneity in human peripheral nerves.

The presence of Fc-receptors for IgG, FcRI (CD64), FcRII (CD32) and FcRIII (CD16) in human peripheral nerves was studied by indirect immunofluorescence staining of cryostat sections with monoclonal antibodies (mabs). The mabs 32.2 against FcRI, IV.3 and C1KM5 against FcRII, B1D6 against a 40 kD FcR with low affinity for IgG, and Leu-11b and 3G8 against FcRIII stained a few scattered cells in the endoneurium, apparently monocytes/macrophages. In addition, B1D6 and Leu11b gave a membranous staining of Schwann cells, endothelial cells and perineurial cells. Axons and fibroblasts were not stained by any of the mabs. The FcR may be important in binding immune complexes, in phagocytosis, in the release of lymphokines as well as cytotoxic and inflammatory mediators and in local immunoregulation.

Antibodies, Monoclonal↗
PubMed1990

Properties of solubilized Fc gamma-receptors from psoriatic scales.

Extracts from psoriatic scales, prepared using Tris-HCl buffer containing ethylenediaminetetraacetatic acid (EDTA) and 2-mercaptoethanol (ME), agglutinated erythrocytes (E) sensitized with IgG antibodies (A) (EA), but not E or E sensitized with F(ab')2-fragments of IgG. The agglutination was inhibited by IgG and Fc fragments of IgG, but not by IgA, IgM or F(ab')2-fragments of IgG. Partially reduced and alkylated IgG did not inhibit the agglutination, indicating that an inter-heavy-chain disulphide-linked Fc region is required for binding of FcR. The extracts inhibited EA, but not E or EAC rosette formation with mononuclear cells. The results strongly indicated that the extract contained functionally active FcR. The agglutinating activity of the extract was not affected by treatment with periodic acid or formaldehyde, whereas heat reduced the activity. Using a monoclonal antibody (B1D6) a functionally active 40 kDa FcR with low affinity for native IgG was purified from the scale extract. The extracts also contained FcR activity not recognized by B1D6.

Antigens, Differentiation↗
PubMed1990

Fc gamma receptor heterogeneity in the human placenta.

Fc receptors for IgG, FcRI (CD64), FcRII (CD32), and FcRIII (CD16) in human placenta were studied by indirect immunohistochemistry using avidin-biotin peroxidase complexes for the staining of cryostat sections. The MoAb 32.2 against FcRI stained cells in the loose connective tissue of the placental villi. The MoAb IV3 (FcRII) and C1KM5 (FcRII) also stained stromal cells and in addition stained the endothelium of the placental villi. The MoAb anti-Leu-11b against FcRIII and B1D6 against a 40-kDa FcR from placenta stained both stromal cells and endothelium as well as the fetal trophoblasts lining the villi. The MoAb 3G8 (FcRIII) also stained trophoblasts and stromal cells but did not stain the endothelium. The heterogeneity of FcR expression on human placenta is established. The function of the different receptors is still unclear.

Antibodies, Monoclonal↗
PubMed1989

Solubilization of human peripheral nerve Fc gamma receptors and purification of a functional 40 kDa receptor.

Extracts from myelinated and unmyelinated nerves, prepared using Tris-HCl buffer with EDTA and ME, contained functionally active receptors for the Fc region of IgG (FcR). This was evident from the results obtained in indirect haemagglutination and rosette inhibition assays. Using a monoclonal antibody, a functional active 40-kDa FcR was purified from the nerve extracts. The receptor was a single-chained glycoprotein with low affinity for native IgG, apparently belonging to the FcRII family. In addition, peripheral nerve extracts contain FcR not recognised by the monoclonal antibody.

Antibodies, Monoclonal↗
PubMed1989

Purification of a functional 40 kD human placental Fc gamma-receptor using a monoclonal antibody.

F(ab')2-fragments of a mouse monoclonal antibody (B1D6) reacting with placental receptors for the Fc part of IgG (FcR) were used as affinity reagents for the purification of an antigen from placental extract (PE). The antigen agglutinated ovine erythrocytes (E) sensitized with rabbit antibodies (A) (EA), but not E or E sensitized with F(ab')2-fragments. It reduced the EA rosette-formation with mononuclear cells and the binding of soluble immune complexes to placental tissue. The antigen bound to aggregated IgG and Fc-fragments of IgG, but not to native IgG or F(ab')2-fragments of IgG. The data indicate that the purified antigen possesses FcR activity with low affinity for IgG. SDS-PAGE and Western blot showed one distinct band of approximately 40 kD. The electrophoretic mobility did not change after reduction and the band reacted with concanavalin A indicating that the FcR are single-chained glycoproteins.

Antibodies, Monoclonal↗
PubMed1983

Ultrastructural study of induced keratinization in sulcular gingival epithelium in rhesus monkeys.

Gingival sulcular epithelium--which in primates normally does not keratinize--can be induced to undergo keratinization by prolonged intensive antibacterial therapy. Three months before biopsy the teeth of two adult male rhesus monkeys were scaled and polished, and for 5 days the monkeys were given intravenous injections of 75 mg Achromycin daily. Their teeth were subsequently subjected to daily cleaning and polishing. The presumably in-situ-keratinized sulcular epithelium was examined by transmission electron microscopy. It was also compared with oral gingival epithelium from the same two animals and with oral and sulcular epithelium from a rhesus monkey that had not been exposed to local or systemic antibacterial therapy. The results confirmed earlier histological studies, which have shown that under the conditions described the sulcular epithelium becomes parakeratinized. In addition, several other ultrastructural changes were observed, some of which suggest that the treatment given may result in the formation of a more efficient permeability barrier in the sulcular area. The possible clinical significance of such a barrier is briefly discussed.

Animals↗