title: Human skin mast cells express functional beta 1 integrins that mediate adhesion to extracellular matrix proteins.
abstract: We have evaluated the adhesion of human cutaneous mast cells to several components of the extracellular matrix (plasma fibronectin, laminin, collagen type I and IV) and studied whether these cells express the beta 1 integrins potentially involved in the adhesion to these proteins. Human skin mast cells (5.1 +/- 1.5% pure) spontaneously adhered to fibronectin and laminin (0.1 to 10 micrograms/ml) immobilized on plastic surfaces (e.g., 14 +/- 7.2% and 14 +/- 4.4% adhesion at 10 micrograms/ml, respectively). Similar results were obtained with a 90% pure mast cell preparation. In contrast, cutaneous mast cells did not adhere to collagen type I (1.6 +/- 0.5% adhesion) or type IV (1.2 +/- 0.8% adhesion). Control adhesion in BSA-coated wells was < 5%. Mast cell adhesion to fibronectin was optimal after an incubation period of 60 to 90 min (t1/2 = 28.2 +/- 6.2 min), whereas adhesion to laminin was faster (t1/2 = 10.1 +/- 1.2 min), being nearly optimal after a 15-min incubation period. Human skin mast cell adhesion to fibronectin and laminin was found to be dependent on the presence of divalent cations in the extracellular medium. Dual-color immunofluorescence and flow cytometry were used to evaluate whether human skin mast cells (51.3 +/- 3.9% pure) express beta 1 integrins that may mediate cell adhesion to extracellular matrix proteins. These mast cells were found to express VLA (very late Ag)-3 (75.3 +/- 35.6 specific fluorescence intensity) and, to lesser degree, VLA-4 and VLA-5 receptors (8.0 +/- 2.5 and 6.9 +/- 3.2 specific fluorescence intensity, respectively). In contrast, VLA-1, VLA-2, and VLA-6 integrins were not expressed significantly. mAb to VLA-3, VLA-4, and VLA-5 each inhibited by 70% skin mast cell adhesion to fibronectin. mAb to VLA-3 nearly abolished mast cells adhesion to laminin, whereas anti-VLA-4 and anti-VLA-5 were ineffective. Finally, immunosuppressant cyclosporin A (100 nM) and FK-506 (10 nM) significantly inhibited mast cell adhesion to both fibronectin and laminin (p < 0.05). Our data demonstrate that human skin mast cells spontaneously adhere to fibronectin and laminin, and that this adhesion is mediated by VLA-3, VLA-4, and/or VLA-5 integrins on these cells. Interactions between these beta 1 integrins and extracellular matrix proteins may be involved in perivascular tissue localization of human mast cells in vivo.
authors.affiliation: Division of Clinical Immunology, University of Naples Federico II School of Medicine, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Columbo
authors.forename: B S
authors.initials: BS
authors.lastname: Bochner
authors.forename: G
authors.initials: G
authors.lastname: Marone
mesh_terms: D002413:Cations, Divalent / Q000494:pharmacology; D002448:Cell Adhesion / Q000276:immunology*; D016572:Cyclosporine / Q000494:pharmacology; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism; D005434:Flow Cytometry; D006632:Histamine / Q000032:analysis; D006801:Humans; D019012:Integrin beta1; D016023:Integrins / Q000096:biosynthesis* / Q000502:physiology*; D007797:Laminin / Q000378:metabolism; D008407:Mast Cells / Q000276:immunology*; D017469:Receptors, Fibronectin / Q000032:analysis; D016029:Receptors, Very Late Antigen / Q000032:analysis; D012867:Skin / Q000166:cytology; D016559:Tacrolimus / Q000494:pharmacology
chemical_list: D002413:Cations, Divalent; D016326:Extracellular Matrix Proteins; D005353:Fibronectins; D019012:Integrin beta1; D016023:Integrins; D007797:Laminin; D017469:Receptors, Fibronectin; D016029:Receptors, Very Late Antigen; D006632:Histamine; D016572:Cyclosporine; D016559:Tacrolimus