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C G Gahmberg

Publications and source records attributed to C G Gahmberg.

At least 73 records · Page 4Linked to original sources
PubMed1990

Participation of CD11a-c/CD18, CD2 and RGD-binding receptors in endogenous and interleukin-2-stimulated NK activity of CD3-negative large granular lymphocytes.

The effect of RGD-sequence-containing pentapeptides and monoclonal antibodies (MAbs) against the adhesion molecules CD11a-c/CD18, ICAM-1 (CD54) and CD2 on the binding and cytotoxicity of endogenous (freshly purified) and IL-2-stimulated CD3-negative NK cells has been studied. Antibody to CD18 exerted the most significant inhibition of adhesion and cytotoxicity of endogenous NK cells to MOLT-4 lymphoma cells, followed by antibodies to CD2 and CD54. Antibodies to either CD11a, CD11b or CD11c did not inhibit adhesion when used separately, whereas as a mixture their inhibitory capacity was as strong as that of anti-CD18. Antibodies against CD18, CD54 and CD2 exerted an additive effect on the inhibition of adhesion. Their combination eradicated the binding of endogenous NK cells. The RGD-containing peptide did not inhibit the binding or cytotoxicity of freshly purified NK cells to MOLT-4, whereas some inhibition was detected against the adenocarcinoma cell line COLO-205. According to FACS analysis, IL-2 increases the expression of CD2 and CD54 on NK cells. However, the relative contribution of the adhesion molecules to the NK cell binding did not change as a result of the stimulation with IL-2. The RGD-peptide substantially inhibited the binding of IL-2-stimulated killer cells to COLO, and the combination of this peptide with MAbs to CD18, CD54 and CD2 practically blocked the adhesion. Our results indicate that both CD11a-c/CD18- (involving the 3 heterodimers) and CD2-dependent adhesion pathways are used by LGL in endogenous and IL-2 stimulated natural killing. In addition, RGD-binding receptors are involved in adhesion to some target cells.

Antigen-Antibody Reactions↗
PubMed1990

The pivotal role of the Leu-CAM and ICAM molecules in human leukocyte adhesion.

Cellular adhesion is of fundamental importance in leukocyte physiology. It is a complex, strictly regulated process, which involves the participation of several cell surface glycoproteins. Among the most important are the Leu-CAMs or the CD11/CD18 integrin receptors, and their adhesion ligands ICAM-1 (CD54) and ICAM-2. In this review we summarize some recent work on various aspects of these molecules.

Antigens, CD↗
PubMed1990

Rabbit leukocyte adhesion molecules CD11/CD18 and their participation in acute and delayed inflammatory responses and leukocyte distribution in vivo.

In humans the glycoprotein complexes CD11/CD18 mediate leukocyte adhesion to cells. Mouse monoclonal antibodies (mAb) 60.3, 7E4, and IB4 to human CD18, found to cross-react with rabbit white blood cells, were used to identify the antigen in rabbit cells and to study adherence of rabbit leukocytes in vitro and in vivo. These antibodies labeled almost all unfractionated rabbit blood leukocytes and immunoprecipitated surface glycopolypeptides with apparent molecular weights of 85,000 and 150,000 from these cells. Adhesion of purified rabbit polymorphonuclear cells (PMNs) to cultured vascular endothelial cells in the presence of phorbol ester was blocked by the antibodies in a dose-dependent manner. The acute inflammatory response characterized by local accumulation of PMNs and concomitant plasma extravasation following intradermal injections of zymosan-activated serum (ZAS) in rabbits was inhibited in animals pretreated intravenously with anti-CD18 mAb. Intravital microscopy of the rabbit tenuissimus muscle demonstrated that anti-CD18 mAb. Intravital microscopy of the rabbit tenuissimus muscle demonstrated that anti-CD18 treatment specifically blocked the adhesion of activated leukocytes to the venular endothelium and thereby the subsequent diapedesis of these cells into the extravascular space. The lymphocyte-dependent tissue swelling resulting from a delayed-type hypersensitivity reaction in the rabbit ear was partially inhibited by anti-CD18 mAb. Systemic anti-CD18 treatment induced a pronounced increase in the number of circulating mononuclear and polymorphonuclear cells with a maximum at 24 hr after injection of the antibody. It is concluded that GP150/GP85 is the rabbit homologue of human CD11/CD18, and that leukocyte-cell adhesion mediated by these glycoprotein complexes participates in acute and delayed inflammatory responses and leukocyte distribution in vivo.

Animals↗
PubMed1990

Leukocyte-cell adhesion: a molecular process fundamental in leukocyte physiology.

Leukocyte-cell adhesion is a form of physical contact characterized by fast (firm) stickiness between the cells. To analyze the biology and molecular basis of this process, an adhesion-specific assay was developed: the phorbol ester-induced aggregation of human lymphocytes. This rapid and antigen-independent intercellular adhesion requires cellular metabolism, an intact cytoskeleton and extracellular divalent cations, and is mediated by preformed cell-surface proteins referred to as CAMs. Phorbol ester also induces aggregation of monocytes and granulocytes, as well as adhesion of T lymphocytes to either B cells or monocytes and of the leukocytes to vascular endothelial cells. By using the adhesion-specific assay and blocking monoclonal antibodies, several CAMs have been identified, namely the Leu-CAM family (CD11a-c/CD18) and ICAM-1 (CD54). The Leu-CAM family is composed of Leu-CAMa (CD11a/CD18), Leu-CAMb (CD11b/CD18) and Leu-CAMc (CD11c/CD18), three glycoprotein heterodimers made of a common beta-chain and distinct alpha-chains. ICAM-1 is an adhesive ligand for Leu-CAMa. Expression and use of the various CAMs is selective in different types of leukocytes. The Leu-CAMs have been purified and partially characterized. CD18, whose gene is on human chromosome 21, contains 5-6 N-linked complex-type oligosaccharides, and CD11 binds Ca++. Another adhesion pathway is mediated by CD2 and CD58. CD2, a glycoprotein selectively expressed by T cells, is a receptor for CD58, a cell-surface adhesive ligand with broad tissue distribution. Antibodies to the latter CAMs do not block the phorbol ester-induced lymphocyte aggregation. Adhesion is involved in a large variety of leukocyte functions. Anti-Leu-CAM antibodies block induction of IL-2 production and lymphocyte proliferation. Lymphocyte-mediated cytotoxicity is also inhibited. Endogenous NK and LAK cells use Leu-CAMs, ICAM-1 and CD2, and sometimes RGD receptors, to bind and kill tumor cells. Endogenous compounds such as H2O2 and LTB4 also induce Leu-CAM-dependent adhesion in monocytoid cells and granulocytes, respectively, and degranulation of the latter cells is enhanced by the adhesion process. Homologous CAMs have been identified in rabbit and mouse. In in vivo studies in the former species, anti-Leu-CAM antibodies block adhesion of leukocytes to vascular endothelium and thereby their migration into extravascular tissues. The antibodies thus inhibit granulocyte accumulation and plasma leakage in inflammatory lesions, and induce lympho- and granulocytosis, indicating that cell-adhesion contributes to the distribution of leukocytes in the body.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Oxidation of glycolipids in liposomes by galactose oxidase.

Small unilamellar phosphatidylcholine vesicles containing globo-series glycolipids were labeled by the galactose oxidase/NaB[3H]4 procedure. The major glycolipid of human red cells, globoside, was the best substrate for galactose oxidase both in vesicles and in tetrahydrofuran-containing buffer. The oxidation rates of membrane-bound ceramide trihexoside and Forssman glycolipid were one-fourth and one-tenth, respectively, of the oxidation rate of globoside. Membrane-bound ceramide dihexoside was not a substrate for galactose oxidase, although it was readily oxidized in tetrahydrofuran-containing buffer. Soluble sialoglycoproteins and membrane-incorporated glycophorin A stimulated the oxidation of globoside-containing vesicles, whereas membrane-bound GD1a ganglioside had no effect on globoside oxidation.

Animals↗
PubMed1988

CD11a-c/CD18 and GP84 (LB-2) adhesion molecules on human large granular lymphocytes and their participation in natural killing.

Effect of mAb against the CD11a-c, CD18, and GP84 adhesion molecules on the binding and cytotoxicity of human NK cells was studied. The target cells were K562, MOLT-4, Raji, and fresh uncultured autologous endometrial carcinoma cells. Antibodies against adhesion relevant epitopes of CD11a(TA-1/LFA-1), CD11b(Mol/OKM1/Mac1), or CD11c (Leu-M5) did not inhibit NK function. The mAb 60.3 against CD18, the common beta-chain associated to CD11a-c, strongly inhibited both the binding and cytotoxicity of large granular lymphocytes (LGL) against all the target cells tested. Also the antibody LB-2 against the GP84 adhesion molecule inhibited NK function to some degree. 60.3 and LB-2 antibodies exerted an additive effect in the inhibition of both binding and cytotoxicity. However, even this antibody combination did not completely block NK activity, suggesting a heterogeneity of adhesion structures in the NK system. According to both FACS analyses and immunoprecipitation studies, all the tested antibodies recognized either a subpopulation or all of LGL. On the other hand, antibodies against CD11b, CD11c, and LB-2 showed only marginal reactivity with highly purified LGL-free T cells.

Antibodies, Monoclonal↗
PubMed1988

Absence, or low expression, of leukocyte adhesion molecules CD11 and CD18 on Burkitt lymphoma cells.

Leukocyte adhesion to cells is mediated by the cell-surface glycoprotein complex CD11a-c/CD18 and, in some cases, the glycoprotein gp84. The process is associated with leukocyte activation and modulates lymphocyte proliferation and maturation. Epstein-Barr virus (EBV)-transformed normal B lymphocytes give rise to lymphoblastoid cell lines (LCLs) which grow as large clusters mediated by adhesion molecules. In contrast, newly explanted EBV-infected Burkitt lymphoma (BL) cells usually grow as single cells or as loose clusters. We now report that EBV positive- and EBV-negative BL lines lack the adhesive protein complex, or have only low levels of it, whereas LCLs, representing various stages of B-lymphocyte development, contain considerably higher amounts, as measured by immunofluorescence flow cytometry and immunoprecipitation. The level of gp84 expression is of the same magnitude in both types of cells.

Antibodies, Monoclonal↗
PubMed1988

Synthesis of fluorescent oligosaccharides for covalent attachment to living cells.

Asparagine-linked oligosaccharides were liberated from glycoproteins by hydrazinolysis. The treatment resulted in de-N-acetylation of the amino sugars. After isolation of the oligosaccharides free amino groups were labeled with fluorescein isothiocyanate and remaining amino groups reacetylated. The fluorescent oligosaccharides were used to label living cells. They were converted to hydrazine derivatives and covalently attached to cell surface oligosaccharides, which had been treated with periodate or neuraminidase and galactose oxidase. This enabled the visualization of the attached oligosaccharides at the external aspect of the plasma membrane by fluorescence microscopy.

Amino Sugars↗
PubMed1988

Fibronectin isoforms in plasma membrane domains of normal and regenerating rat liver.

Plasma membrane fractions were obtained from the three surface domains of normal and regenerating adult rat livers. It was shown by immunoblotting that sinusoidal plasma membranes contained the characteristic 220 and 210 kDa fibronectin doublet, whereas bile canalicular plasma membranes contained a 220 kDa component. In lateral plasma membranes, 180, 190 and 220 kDa fibronectin isoforms were present. Fibronectin in the sinusoidal and canalicular plasma membranes was shown, by detergent/aqueous phase partitioning, to be more hydrophilic than isoforms in lateral plasma membranes. Changes in the distribution of fibronectin between plasma membrane domains occurred during liver regeneration and their significance, especially in relation to cell division, is discussed.

Animals↗
PubMed1988

Purification in large scale and characterization of the human leukocyte adhesion glycoprotein GP90 (CD18).

The leukocyte adhesion 90-kDa glycoprotein GP90 (antigen CD18) is non-covalently associated separately with cell-surface glycoproteins GP160 (antigens CD11a, TA-1, LFA-1), GP155 (antigens CD11b, OKM1, MO1) or GP130 (antigens CD 11c, Leu-M5). Large amounts of these protein complexes were purified to homogeneity from blood mononuclear leukocytes by immunoaffinity chromatography using a monoclonal antibody. GP90 was further isolated by preparative gel electrophoresis in the presence of sodium dodecyl sulfate. Rabbit antiserum towards the complex inhibited phorbol-ester-induced adhesion of leukocytes. The antiserum towards purified GP90 reacted more strongly with the denatured GP90 protein, but showed reactivity also with GP160 protein, indicating structural homologies between GP90 and GP160. The amino acid composition of GP90 was determined. Its N-terminus was found to be blocked. Treatment of GP90 with endo-beta-N-acetylglucosaminidase F, but not with endo-beta-N-acetylglucosaminidase H, reduced the apparent molecular mass to 75 kDa, indicating the presence of five or six N-linked complex-type oligosaccharides/molecule.

Amino Acids↗
PubMed1988

Major O-glycosylated sialoglycoproteins of human hematopoietic cells: differentiation antigens with poorly understood functions.

All human hematopoietic cells seem to contain a major, heavily O-glycosylated sialoglycoprotein. Glycophorin A is specific for the erythroid lineage of cells, and leukocytes have a major sialoglycoprotein, also called leukosialin or sialophorin. Cell differentiation results in patterns of O-glycosylation in these proteins, which reflect the stage of differentiation within a cell lineage as well as lineage specificity. The altered carbohydrate compositions may influence the interactions of the cells with external ligands. Healthy individuals lacking glycophorin A in their red cells are known, whereas a deficiency of the leukocyte sialoglycoprotein may result in immunological disease. Although little is known about the physiological functions of these proteins, they form interesting models for studies on regulation of glycosylation, biosynthesis of O-glycosylated glycoproteins, and function of cell surface receptors.

Antigens, Differentiation↗
PubMed1988

Adhesion-mediating molecules of human monocytes.

Adhesion of monocytes to each other and to T cells and substrates is increased by phorbol esters. In the presence of these compounds monocyte aggregation was almost completely inhibited (greater than 90%) by monoclonal antibody 60.3. This antibody recognizes GP90 (CD18), a leukocyte surface glycoprotein which is separately and noncovalently associated to either GP160 (CD11a), GP155 (CD11b), or GP130 (CD11c). Anti-LFA-1 antibody (CD11a) was only partially inhibitory (35%) while antibodies 60.1 (CD11b) and anti-Leu-M5 (CD11c) had a minimal inhibitory effect (10%). Antibody LB-2 recognizing a single glycoprotein distinct from the GP90-GP160 complex and expressed on activated B and T cells, monocytes, and vascular endothelial cells was partially inhibitory (22%). Monoclonal antibodies anti-C3bR (CD35), T29/33 (CD45, leukocyte common antigen 200). TA-1 (CD11a), OKM1 (CD11b), F10-44-2 (brain-leukocyte antigen), OKM5 (monocyte-endothelial cell antigen) and to class I or class II molecules exerted no inhibition on the monocyte aggregation. Fab fragments of antibody 60.3 efficiently inhibited not only monocyte aggregation in the absence or presence of phorbol esters but also adhesion of these cells to autologous or allogeneic T lymphocytes and, to a lesser extent, to plastic surfaces. It is thus concluded that GP90, either alone or associated to the larger glycoproteins, and LB-2 antigen mediate monocyte adhesion.

Antibodies, Monoclonal↗
PubMed1988

Detection of glycoproteins in the Acanthamoeba plasma membrane.

In the present study we have shown that glycoproteins are present in the plasma membrane of Acanthamoeba castellanii by utilizing different radioactive labeling techniques. Plasma membrane proteins in the amoeba were iodinated by 125I-lactoperoxidase labeling and the solubilized radiolabeled glycoproteins were separated by lectin-Sepharose affinity chromatography followed by polyacrylamide gel electrophoresis. The periodate/NaB3H4 and galactose oxidase/NaB3H4 labeling techniques were used for labeling of surface carbohydrates in the amoeba. Several surface-labeled glycoproteins were observed in addition to a diffusely labeled region with Mr of 55,000-75,000 seen on electrophoresis, which could represent glycolipids. The presence of glycoproteins in the plasma membrane of Acanthamoeba castellanii was confirmed by metabolic labeling with [35S]methionine followed by lectin-Sepharose affinity chromatography and polyacrylamide gel electrophoresis.

Acanthamoeba↗
PubMed1988

Immunological mapping of the human leucocyte adhesion glycoprotein gp90 (CD18) by monoclonal antibodies.

The leucocyte surface glycoproteins CD11a (gp160, LFA-1 antigen, TA-1 antigen), CD11b (gp155, Mac-1 antigen, OKM1 antigen, Mo-1 antigen), CD11c (gp130, Leu-M5 antigen), and CD18 (gp90) constitute three heterodimers with different alpha chains and a common beta chain. Monoclonal antibodies to CD11a, b, or c block adhesion of certain types of leucocytes only, while several antibodies to CD18 inhibit adhesion in all of them. The functionally important site or sites on CD18 are not known. We have now isolated the CD11a,b,c-CD18 leucocyte antigen complex in large amounts from human leucocytes, and produced several new monoclonal antibodies reacting with CD18. One of these antibodies, like those described earlier, inhibits leucocyte adhesion, whereas the others do not. By means of competition experiments, at least four epitope regions were found. These antibodies should be valuable in elucidating the regions essential in CD18-mediated leucocyte functions.

Animals↗
PubMed1987

Identification of a novel adhesion molecule in human leukocytes by monoclonal antibody LB-2.

Monoclonal antibody LB-2 to a surface antigen on human B cells, lymphoblast, monocytes and vascular endothelial cells largely inhibited adhesion among Epstein Barr virus-immortalized normal B cells (EBV-B) and concanavalin A-stimulated blood mononuclear cells (Con A-BMC) before and after phorbol ester treatment. The antibody inhibited to a lesser extent phorbol ester-induced aggregation of monocytes, U937 cells and fresh BMC and had virtually no inhibitory effect on the adhesion among enriched T cells and granulocytes. A surface glycoprotein band of 84 kDa was obtained from EBV-B cells by immunoprecipitation and gel electrophoresis. Immunological and biochemical studies clearly distinguished this molecule from gp90 and associated glycoproteins which also mediate leukocyte adhesion.

Antibodies, Monoclonal↗
PubMed1987

Phorbol diesters increase the phosphorylation of the leukocyte common antigen CD45 in human T cells.

We have studied the phosphorylation of the human leukocyte surface glycoprotein CD45, formerly known as leukocyte common antigen or T200, following activation of peripheral T cells with tumor-promoting phorbol diesters. The cells were incubated with [32P]orthophosphate, treated with phorbol diesters, and the CD45 was immunoprecipitated using the monoclonal antibody T29/33. CD45 was weakly phosphorylated in nonactivated T cells, but a treatment of the cells with 10, 60 or 200 nM phorbol 12,13-dibutyrate (PDBu) markedly increased the phosphorylation of the glycoprotein. This effect of PDBu was relatively selective for CD45 since the activation of the cells did not affect the phosphorylation of all membrane phosphoglycoproteins. The effect of another tumor promoter, phorbol 12-myristate 13-acetate (PMA), was comparable to that of PDBu, but a nontumor-promoting phorbol derivative, 4 alpha-phorbol 12,13-didecanoate, did not change the level of CD45 phosphorylation. The phosphorylation of CD45 was found to clearly increase after a treatment of T cells with 60 nM PDBu for only 30 s, and the phosphorylation reached its maximum in about 5 min.

Dose-Response Relationship, Drug↗
PubMed1987

Oncoplacental protein SP1--a constitutive and inducible late differentiation marker of the human myelomonocytic lineage.

The oncoplacental protein SP1 is found in large quantities in human placenta, amniotic fluid, and pregnancy serum. Low levels have been reported in association with malignancy but also in healthy nonpregnant individuals. By indirect immunofluorescence, fluorescence-activated cell sorting, and immunoprecipitation we here demonstrate the presence of SP1 both on the surface and in the cytoplasm of human granulocytes but not in earlier myeloid progenitor cells in bone marrow. Lymphocytes did not contain the protein, and only trace amounts could be found in the cytoplasm of blood monocytes. A major glycoprotein with an apparent mol wt of 90,000 was obtained by immunoprecipitation of surface-labeled granulocytes. Cultivated blood monocytes, while adhering to surfaces or forming multinuclear giant cells, displayed a strong membrane and cytoplasmic expression of SP1. Treatment of the myeloid leukemia cell line ML-2 with tetraphorbol acetate (TPA) strongly induced SP1 in the membrane and cytoplasm as revealed by immunofluorescence and polyacrylamide gel electrophoresis (PAGE) of immunoprecipitates from lysates of surface radiolabeled cells. The induction of synthesis of SP1 in TPA-treated cells was confirmed by immunoprecipitation from lysates of cells metabolically labeled with 35S-methionine. Human lymphoblastoid and erythroleukemic cell lines did not express SP1 either before or after induced differentiation. Thus SP1 provides a late differentiation marker for the myelomonocytic lineage and is strongly induced during macrophage differentiation or by TPA treatment of ML-2 cells.

Cell Differentiation↗