title: 2B4, the natural killer and T cell immunoglobulin superfamily surface protein, is a ligand for CD48.
abstract: 2B4 is a cell surface glycoprotein related to CD2 and implicated in the regulation of natural killer and T lymphocyte function. A recombinant protein containing the extracellular region of mouse (m)2B4 attached to avidin-coated fluorescent beads bound to rodent cells, and binding was completely blocked by CD48 monoclonal antibodies (mAbs). Using surface plasmon resonance, we showed that purified soluble mCD48 bound m2B4 with a six- to ninefold higher affinity (Kd approximately 16 microM at 37 degreesC) than its other ligand, CD2. Human CD48 bound human 2B4 with a similar affinity (Kd approximately 8 microM). The finding of an additional ligand for CD48 provides an explanation for distinct functional effects observed on perturbing CD2 and CD48 with mAbs or by genetic manipulation.
authors.affiliation: Medical Research Council Cellular Immunology Unit, Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom.
authors.forename: M H
authors.initials: MH
authors.lastname: Brown
authors.forename: K
authors.initials: K
authors.lastname: Boles
authors.forename: P A
authors.initials: PA
authors.lastname: van der Merwe
authors.forename: V
authors.initials: V
authors.lastname: Kumar
authors.forename: P A
authors.initials: PA
authors.lastname: Mathew
authors.forename: A N
authors.initials: AN
authors.lastname: Barclay
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000276:immunology*; D000071178:CD48 Antigen; D005434:Flow Cytometry; D006801:Humans; D007136:Immunoglobulins / Q000276:immunology*; D007694:Killer Cells, Natural / Q000276:immunology*; D008024:Ligands; D008562:Membrane Glycoproteins / Q000276:immunology*; D051379:Mice; D011971:Receptors, Immunologic; D000071176:Signaling Lymphocytic Activation Molecule Family; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D015703:Antigens, CD; C084093:CD244 protein, human; D000071178:CD48 Antigen; C000604065:CD48 protein, human; C490007:Cd244a protein, mouse; C000604066:Cd48 protein, mouse; D007136:Immunoglobulins; D008024:Ligands; D008562:Membrane Glycoproteins; D011971:Receptors, Immunologic; D000071176:Signaling Lymphocytic Activation Molecule Family