title: Release and intercellular transfer of cell surface CD81 via microparticles.
abstract: The human tetraspan molecule CD81 is a coreceptor in B and T cell activation and a candidate receptor for hepatitis C virus infection. We examined the surface expression of CD81 on B and T lymphocytes by quantitative flow cytometry. Upon cellular activation, CD81 surface levels were rapidly reduced. This reduction occurred as early as 1 h after activation and was linked to the release of CD81-positive microparticles into the cell culture medium. CD81 mRNA levels were not affected early after activation, but the release of CD81-positive microparticles was rapidly enhanced. In addition, intercellular transfer of CD81 was observed upon coculture of CD81-positive donor cells (Jurkat T cell line) with CD81-negative acceptor cells (U937 promonocytic cell line). This transfer was rapidly increased upon T cell activation, coinciding with enhanced CD81 release from activated Jurkat cells. We propose that the release and intercellular trafficking of CD81-positive microparticles regulate the expression of CD81 surface receptors in lymphocytes and play a role in the immune response during infections.
authors.affiliation: Divisions of Applied Tumorvirology, Deutsches Krebsforschungszentrum, Heidelberg, Germany.
authors.forename: Benedikt
authors.initials: B
authors.lastname: Fritzsching
authors.forename: Björn
authors.initials: B
authors.lastname: Schwer
authors.forename: Jürgen
authors.initials: J
authors.lastname: Kartenbeck
authors.forename: Angelika
authors.initials: A
authors.lastname: Pedal
authors.forename: Vaclav
authors.initials: V
authors.lastname: Horejsi
authors.forename: Melanie
authors.initials: M
authors.lastname: Ott
mesh_terms: D015703:Antigens, CD / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D016175:B-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism; D002450:Cell Communication / Q000235:genetics / Q000276:immunology*; D002462:Cell Membrane / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D002474:Cell-Free System / Q000276:immunology / Q000378:metabolism; D002478:Cells, Cultured; D002499:Centrifugation, Density Gradient; D018920:Coculture Techniques; D015536:Down-Regulation / Q000276:immunology; D011992:Endosomes / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000648:ultrastructure; D005089:Exocytosis / Q000235:genetics / Q000276:immunology; D005110:Extracellular Space / Q000276:immunology* / Q000378:metabolism*; D006801:Humans; D019169:Jurkat Cells / Q000276:immunology / Q000378:metabolism / Q000648:ultrastructure; D008213:Lymphocyte Activation / Q000276:immunology; D008565:Membrane Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D021381:Protein Transport / Q000276:immunology; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000378:metabolism; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism / Q000648:ultrastructure; D060225:Tetraspanin 28; D020298:U937 Cells
chemical_list: D015703:Antigens, CD; C554798:CD81 protein, human; D008565:Membrane Proteins; D012333:RNA, Messenger; D060225:Tetraspanin 28