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Biomedical subjects

A Aruffo

Publications and source records attributed to A Aruffo.

At least 181 records · Page 10Linked to original sources
PubMed1992

Granule membrane protein 140 (GMP140) binds to carcinomas and carcinoma-derived cell lines.

The glycoproteins granule membrane protein 140 (GMP140), endothelial-leukocyte adhesion molecule 1 (ELAM-1), and Leu-8 are members of a family of glycoprotein receptors (selectins or LEC-CAMs) that play an important role in adhesive interactions between circulating leukocytes and vascular endothelium. Recently it has been reported that ELAM-1 is able to mediate the binding of the colon carcinoma cell line HT-29 to cytokine-activated vascular endothelium, suggesting that tumor cell adhesion to vascular endothelium, a prerequisite for tumor extravasation and metastasis, is in part the result of adhesive interactions between blood-borne tumor cells and cell surface proteins expressed by vascular endothelium. Here, using an approach in which soluble immunoglobulin chimeras of the GMP140 and ELAM-1 receptors were prepared and used to carry out immunohistological studies, we establish that GMP140 binds to tumor cells in a variety of human carcinoma tissue sections (colon, lung, and breast), whereas ELAM-1 binds exclusively to tumor cells in colon carcinoma tissue sections. In addition, GMP140 was found to bind to the cell surface of a number of cell lines derived from various carcinomas but not from melanomas, whereas ELAM-1 bound only colon carcinoma cell lines. We further investigated the nature of the ligands of GMP140 and ELAM-1 on the surface of the carcinoma cells and found that the GMP140 ligand on the surface of tumor cells appears to be distinct from that expressed on the myeloid cell line HL-60. Neuraminidase treatment of a breast carcinoma cell line does not affect, or in some instances increases, GMP140 binding, whereas it completely abolishes GMP140 binding to HL-60 cells. On the other hand, the ligand of ELAM-1 on both the colon carcinoma and HL-60 cells is neuraminidase sensitive in accord with its identification as sialyl-CD15. Parallel results were obtained with neuraminidase-treated frozen carcinoma tissue sections. The present findings form the basis for investigating the role of GMP140 in tumor invasiveness and metastasis.

Antibodies, Monoclonal↗
PubMed1992

Heat-stable antigen is a costimulatory molecule for CD4 T cell growth.

Optimal induction of clonal expansion by normal CD4 T cells requires a ligand that can engage the T cell receptor as well as functionally defined costimulatory activity on the same antigen-presenting cell surface. While the presence of effective costimulation induces proliferation, T cell receptor ligation in its absence renders T cells inactive or anergic. The molecular basis of this costimulatory activity remains to be defined. Here we describe a monoclonal antibody that can block the costimulatory activity of splenic accessory cells. Treatment with this antibody not only blocks the proliferation of CD4 T cells to a T cell receptor ligand, but also induces T cell nonresponsiveness to subsequent stimulation. Sequence analysis of the antigen recognized by this antibody indicates that it recognizes a protein that is identical to heat-stable antigen. Gene transfer experiments directly demonstrate that this protein has costimulatory activity. Thus, heat-stable antigen meets the criteria for a costimulator of T cell clonal expansion.

Animals↗
PubMed1992

Intercellular adhesion molecule-2, a second counter-receptor for CD11a/CD18 (leukocyte function-associated antigen-1), provides a costimulatory signal for T-cell receptor-initiated activation of human T cells.

Activation of T cells often requires both activation signals delivered by ligation of the TCR and those resulting from costimulatory interactions between certain T cell surface accessory molecules and their respective counter-receptors on APC. CD11a/CD18 complex on T cells modulate the activation of T cells by interacting with its counter-receptors intracellular adhesion molecule (ICAM-1) (CD54) and/or ICAM-2 on the surface of APC. The costimulatory ability of ICAM-1 has been demonstrated. Using a soluble ICAM-2 Ig fusion protein (receptor globulin, Rg) we demonstrate the costimulatory effect of ICAM-2 during the activation of CD4+ T cells. When coimmobilized with anti-TCR-1 mAb ICAM-2 Rg induced vigorous proliferative response of CD4+ T cells. This costimulatory effect of ICAM-2 was dependent on its coimmobilization with mAb directed at the CD3/TCR complex but not those directed at CD2 or CD28. Both resting as well as Ag-primed CD4+ T cells responded to the costimulatory effects of ICAM-2. The addition of mAb directed at the CD11a or CD18 molecules almost completely inhibited the responses to ICAM-2 Rg. These results are consistent with the role of CD11a/CD18 complex as a receptor for ICAM-2 mediating its costimulatory effects. Stimulation of T cells with coimmobilized anti-TCR-1 and ICAM-2 resulted in the induction of IL-2R (CD25), and anti-Tac (CD25) mAb inhibited this response suggesting the contribution of endogenously synthesized IL-2 during this stimulation. These results demonstrate that like its homologue ICAM-1, ICAM-2 also exerts a strong costimulatory effect during the TCR-initiated activation of T cells. The costimulatory effects generated by the CD11a/CD18:ICAM-2 interaction may be critical during the initiation of T cell activation by ICAM-1low APC.

Antigen-Presenting Cells↗
PubMed1992

GMP-140 (P-selectin/CD62) binds to chronically stimulated but not resting CD4+ T lymphocytes and regulates their production of proinflammatory cytokines.

GMP-140 (P-selectin), a 140-kDa granular membrane glycoprotein localized to the alpha granules of platelets and the Weibel-Palade bodies of endothelial cells, is thought to play an important role in adhesive interactions predominantly between granulocytes, platelets and vascular endothelial cells during inflammation. Although GMP-140 binds to granulocytes, its binding to lymphocytes has not been demonstrated. Using genetically engineered IgG C gamma 1 fusion protein of the extracellular domains of GMP-140, we demonstrate that GMP-140 binds to chronically antigen (Ag)-stimulated CD4+ T cells. Freshly isolated CD4+ T cells did not bind GMP-140, but priming and subsequent stimulation with alloantigen induced and gradually increased expression of GMP-140-reactive structures on their surface. T cells isolated from rheumatoid synovial fluids also exhibited strong binding to GMP-140. The binding of GMP-140 to primed T cells is not influenced by preactivation with phorbol 12-myristate 13-acetate, is almost completely abolished by pretreatment of T cells with neuraminidase or trypsin, and is also strongly inhibited by EDTA, the soluble sulfated glycans dextran sulfate, fucoidan, and heparin, but not by chondroitin sulfates. In spite of its strong binding to Ag-primed T cells, GMP-140 did not modulate the proliferative responses of these cells to various stimuli. However, GMP-140 in conjunction with anti-T cell receptor alpha beta monoclonal antibodies augmented the production of granulocyte-macrophage colony-stimulating factor GM-CSF and inhibited the production of interleukin-8 by Ag-primed T cells without influencing their tumor necrosis factor-alpha production. These results suggest that GMP-140 binds to chronically stimulated CD4+ T cells and differentially modulates their production of proinflammatory cytokines. The ability of Ag-primed T cells to bind GMP-140 may facilitate interactions with activated platelets and endothelial cells affecting the course of inflammation.

CD4-Positive T-Lymphocytes↗
PubMed1992

The human T cell antigen gp39, a member of the TNF gene family, is a ligand for the CD40 receptor: expression of a soluble form of gp39 with B cell co-stimulatory activity.

Signals delivered to B cells via CD40 can synergize with those provided by other B cell surface receptors to induce B cell proliferation and antibody class switching as well as modulate cytokine production and cell adhesion. Recently, it has been shown that the ligand for CD40 is a cell surface protein of approximately 39 kDa expressed by activated T cells, gp39. Here we report on the isolation and characterization of a cDNA clone encoding human gp39, a type II membrane protein with homology to TNF, and the construction and characterization of a soluble recombinant form of gp39. COS cell transfectants expressing gp39 synergized with either anti-CD20 mAb or PMA to drive strong B cell proliferation and alone were able to drive B cells to proliferate weakly. In all cases the B cell proliferation induced by gp39-expressing COS cells was reduced to background levels by the addition of soluble CD40. Unlike gp39-expressing COS cells, recombinant soluble gp39 was not mitogenic alone and required co-stimulation to drive B cell proliferation. These results suggest that B cells require a second signal besides gp39-CD40 to drive proliferation and that soluble gp39 alone in a non-membrane bound form is able to provide co-stimulatory signals to B cells.

Amino Acid Sequence↗
PubMed1992

PMN binding to P-selectin is inhibited by sulfatide.

The endothelial adhesion protein P-selectin binds to a ligand present on the surface of leukocytes. We have characterized the binding interaction between P-selectin and polymorphonuclear leukocytes (PMNs) in an in vitro assay. These studies have utilized a soluble chimeric protein termed receptor globulin (Rg), which consists of the lectin-EGF-CR-CR extracellular domains of P-selectin fused to a human immunoglobulin G Fc domain. The PMNs bound to immobilized Rg in a saturable and concentration-dependent manner. The binding was specific for the Rg, as preincubation of the cells with soluble Rg inhibited binding to immobilized Rg, and binding was dependent on the presence of free divalent cations. The PMNs expressed a ligand for both P-selectin and E-selectin but not for L-selectin. Previously it was shown that sulfatide is a ligand for P-selectin binding in transformed cells. We have demonstrated that the presence of sulfatide in the P-selectin-PMN adhesion assay inhibits binding in a dose-dependent manner.

Antigens, CD↗
PubMed1992

Recombinant globulins: novel research tools and possible pharmaceuticals.

A novel approach to the study of proteins is the construction of chimeras consisting of a target protein fused to an immunoglobulin constant domain. These recombinant globulins have been used in the identification of ligand-receptor pairs, determination of functional consequences of receptor engagement, the elucidation of structural domains necessary for ligand binding, and as potential therapeutic agents.

Animals↗
PubMed1991

Expression cloning of an adenylate cyclase-coupled calcitonin receptor.

A calcitonin receptor complementary DNA (cDNA) was cloned by expression of a cDNA library from a porcine kidney epithelial cell line in COS cells. The 482-amino acid receptor has high affinity for salmon calcitonin (dissociation constant Kd approximately 6 nM) and is functionally coupled to increases in intracellular cyclic adenosine monophosphate (cAMP). The receptor shows no sequence similarity to other reported G protein-coupled receptors but is homologous to the parathyroid hormone-parathyroid hormone-related peptide (PTH-PTHrP) receptor, indicating that the receptors for these hormones, which regulate calcium homeostasis, represent a new family of G protein-coupled receptors.

Adenylyl Cyclases↗
PubMed1991

CD62/P-selectin recognition of myeloid and tumor cell sulfatides.

CD62, also called PADGEM protein, GMP-140, or P-selectin, is a granule membrane protein of endothelial cells and platelets that is mobilized to the plasma membrane following exposure to mediators such as thrombin, histamine, complement components, or peroxides. Data presented to date suggest that one ligand of CD62 includes CD15 (Lewis x determinant) and sialic acid. We show here that sulfatides, heterogeneous 3-sulfated galactosyl ceramides, are an apparently unrelated ligand of CD62. Sulfatides are expressed on the plasma membrane of, and are excreted by, granulocytes, and constitute the principal ligand for CD62 on the plasma membrane of some tumor cells. CD62 binds to sulfatides adsorbed to plastic as avidly as it binds to myeloid or tumor cells. We find that granulocytes excrete sulfatides at a rate predicted to allow them to be rapidly released from CD62 once they have exited the bloodstream.

Animals↗
PubMed1991

The lymphocyte glycoprotein CD6 contains a repeated domain structure characteristic of a new family of cell surface and secreted proteins.

The isolation, characterization, and expression of a full-length cDNA encoding the human T cell glycoprotein CD6 is described. COS cells transfected with the CD6 clone express a 90-kD protein that reacts with all available anti-CD6 monoclonal antibodies. RNA blot hybridization analysis indicates that CD6 transcripts are predominantly restricted to cells in the T lineage. The predicted CD6 sequence is 468 amino acids long, with the typical features of a type I integral membrane protein. The cytoplasmic domain of CD6 contains two serine residues, one or both of which are substrates for phosphorylation during T cell activation. The extracellular domain of CD6 is significantly related to the extracellular domain of the human and mouse T cell antigen CD5, the cysteine-rich domain of the bovine and mouse type I macrophage scavenger receptor, the extracellular domain of the sea urchin spermatozoa protein that crosslinks the egg peptide speract, the mammalian complement factor 1, and the human lung tumor antigen L3. These molecules, therefore, constitute a new gene superfamily that is well conserved across species boundaries.

Amino Acid Sequence↗
PubMed1991

The B lymphocyte adhesion molecule CD22 interacts with leukocyte common antigen CD45RO on T cells and alpha 2-6 sialyltransferase, CD75, on B cells.

Functional maturation of B lymphocytes correlates with expression of the B lineage-specific cell surface glycoprotein CD22. Two CD22 polypeptides have been characterized and suggested to play a role in B cell-B cell interaction as well as in B cell adhesion to monocytes. In this work we provide evidence that CD22 is directly involved in the cognate interaction between B and T cells. One of the two CD22 polypeptides, CD22 beta, interacts with a specific ligand on a subpopulation of CD4+ T cells. Our results suggest that the T cell ligand of CD22 is CD45RO, an isoform of the leukocyte common antigen class of phosphotyrosine phosphatases associated with the helper T cell phenotype. We further demonstrate that CD22 recognizes a second ligand, CD75, expressed predominantly on activated B cells and shown to be a cell surface alpha 2-6 sialyltransferase.

Antibodies, Monoclonal↗
PubMed1991

Vascular cell adhesion molecule 1 induces T-cell antigen receptor-dependent activation of CD4+T lymphocytes.

Effective stimulation of CD4+ T cells in an immune response depends on activation signals transduced via not only the CD3-T-cell receptor (TCR) complex but also those generated by accessory cell-surface proteins, including some that mediate adhesion between T cells and antigen-presenting cells (APC). Three members of the Ig superfamily, CD54 [intercellular cell adhesion molecule 1 (ICAM-1)], CD58 [lymphocyte function-associated antigen 3 (LFA-3)], and B7, expressed on the surface of APC, have been shown to mediate both adhesion and signaling during T cell-APC interactions. Recently another member of the Ig superfamily, [vascular cell adhesion molecule 1 (VCAM-1; INCAM110)], has been identified. VCAM-1 mediates adhesion between endothelial cells and activated lymphocytes and certain tumor cells. Here, using a soluble VCAM-1 fusion protein with receptor globulin (Rg), we examined the role of VCAM-1 in T-cell activation. We observed that CD4+ T cells, which are inefficiently stimulated by immobilized anti-TCR-1 or anti-CD3 monoclonal antibody (mAb) alone, can be induced to proliferate when exposed to immobilized VCAM-1-Rg in conjunction with either immobilized anti-TCR-1 or immobilized anti-CD3 mAb. The costimulatory effects of VCAM-1-Rg on CD4+T cells is inhibited by mAb to either the CD29 (integrin beta 1)-CD49d [very late activation antigen 4 alpha (VLA-4 alpha)] complex on the surface of CD4+ T cells or to VCAM-1. Stimulation of CD4+ T cells with immobilized VCAM-1-Rg and anti-TCR or -CD3 mAb results in the synthesis of both interleukin 2 (IL-2) receptors and IL-2. In addition, anti-CD25 (anti-IL-2 receptor a) mAb significantly inhibited the VCAM-1-Rg/anti-TCR or -CD3 mAb-driven activation of CD4+ T cells, indicating that endogenously produced IL-2 is in part responsible for the observed T-cell proliferation. Collectively, these results suggest that VCAM-1 can play an important costimulatory role during the activation of CD4+ T cells.

Antibodies, Monoclonal↗
PubMed1991

Binding of the B cell activation antigen B7 to CD28 costimulates T cell proliferation and interleukin 2 mRNA accumulation.

A successful immune response requires intercellular contact between T and B lymphocytes. We recently showed that CD28, a T cell surface protein that regulates an activation pathway, could mediate intercellular adhesion with activated B cells by interaction with the B7 antigen. Here we show that CD28 is the primary receptor for B7 on activated peripheral blood T cells, that CD28 binds to B7 in the absence of other accessory molecules, and that interaction between CD28 and B7 is costimulatory for T cell activation. To characterize the binding of CD28 to B7, we have produced genetic fusions of the extracellular portions of B7 and CD28, and immunoglobulin (Ig) C gamma 1 chains. 125I-labeled B7 Ig bound to CD28-transfected Chinese hamster ovary (CHO) cells, and to immobilized CD28 Ig with a Kd approximately 200 nM. B7 Ig also inhibited CD28-mediated cellular adhesion. The function of CD28-B7 interactions during T cell activation was investigated with soluble fusion proteins and with B7-transfected CHO cells. Immobilized B7 Ig and B7+ CHO cells costimulated T cell proliferation. Stimulation of T cells with B7+ CHO cells also specifically increased levels of interleukin 2 transcripts. These results demonstrate that the CD28 signaling pathway could be activated by B7, resulting in increased T cell cytokine production and T cell proliferation. Cellular interactions mediated by B7 and CD28 may represent an important component of the functional interactions between T and B lymphoid cells.

Animals↗
PubMed1991

The hematopoietic and epithelial forms of CD44 are distinct polypeptides with different adhesion potentials for hyaluronate-bearing cells.

CD44 is a polymorphic integral membrane protein which recognizes hyaluronate and whose proposed roles encompass lymphocyte activation, matrix adhesion and the attachment of lymphocytes to lymph node high endothelial venules (HEVs). Immunochemical and RNA blot data have supported the existence of two forms of CD44: a hematopoietic form expressed by cells of mesodermal origin (and by some carcinoma cell lines) and an epithelial form weakly expressed by normal epithelium but highly expressed by carcinomas. This report describes the isolation of a cDNA encoding a distinct CD44 polypeptide expressed by epithelial cells. Re-expression of each form of CD44 in a B cell line allowed cells transfected with the hematopoietic but not the epithelial form to bind to viable rat lymph node HEV cells in primary culture.

Amino Acid Sequence↗
PubMed1991

Expression cloning systems.

This review will cover the use of expression cloning in Xenopus oocytes, fission yeast, and mammalian cells. Of the systems covered herein, transient expression cloning systems in Xenopus oocytes and mammalian cells have proven to be the most effective and versatile, as demonstrated by the large number of cDNA clones isolated by these two methods in the past year. Of particular interest, are recent advances in the screening methodologies used in conjunction with transient expression in mammalian cells which have permitted the application of this system in the isolation of cDNAs encoding intracellular proteins.

Animals↗