title: CD6 dependent interactions of T cells and keratinocytes: functional evidence for a second CD6 ligand on gamma-interferon activated keratinocytes.
abstract: The CD6 glycoprotein is expressed by T lymphocytes and is hypothesized to interact with one or more ligands expressed on antigen presenting cells (APCs). We show that CD6 mediates binding of the transformed CD4+ T cell line Hut 78 to gamma-interferon activated keratinocytes (KCs). A recombinant CD6-Ig fusion protein has been reported to bind to a CD6 ligand ALCAM, but this is the first demonstration that cell-cell adhesion of human T lymphocytes can be CD6 dependent. The known CD6 ligand ALCAM (CD166) is expressed on cultured KCs but does not appear to mediate KC-Hut 78 binding, suggesting the existence of additional CD6 ligands expressed on KCs. In functional studies using autologous KCs as APCs for tetanus toxoid specific T cell clones, KCs +/- gamma-interferon are unable to stimulate autologous T cells with recall antigen. Therefore interaction of T cell CD6 with CD6 ligands on KCs does not provide sufficient co-stimulation of primed T cells to support responses to nominal antigen.
authors.affiliation: Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109-0531, USA.
authors.forename: N G
authors.initials: NG
authors.lastname: Singer
authors.forename: R
authors.initials: R
authors.lastname: Mitra
authors.forename: F
authors.initials: F
authors.lastname: Lialios
authors.forename: B C
authors.initials: BC
authors.lastname: Richardson
authors.forename: R M
authors.initials: RM
authors.lastname: Marks
authors.forename: J M
authors.initials: JM
authors.lastname: Pesando
authors.forename: D A
authors.initials: DA
authors.lastname: Fox
authors.forename: B J
authors.initials: BJ
authors.lastname: Nickoloff
mesh_terms: D020410:Activated-Leukocyte Cell Adhesion Molecule; D015703:Antigens, CD / Q000276:immunology*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology*; D002448:Cell Adhesion; D006023:Glycoproteins / Q000032:analysis / Q000276:immunology*; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D015603:Keratinocytes / Q000187:drug effects / Q000276:immunology*; D008213:Lymphocyte Activation; D013601:T-Lymphocytes / Q000276:immunology*; D013950:Thymus Gland / Q000276:immunology
chemical_list: D020410:Activated-Leukocyte Cell Adhesion Molecule; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; C062279:CD6 antigen; D006023:Glycoproteins; D007371:Interferon-gamma