title: CS1, a novel member of the CD2 family, is homophilic and regulates NK cell function.
abstract: CS1 is a novel member of the CD2 subset of immunoglobulin superfamily (IgSF) expressed on NK, T and stimulated B cells. The cytoplasmic domain of CS1 contains immunoreceptor tyrosine-based switch motif (ITSM) which is present in 2B4, SLAM and CD84. The signaling adaptor molecule SAP/SH2D1A, the defective gene in X-linked lymphoproliferative disease (XLPD), binds to ITSM and regulates immune cell function. However, recent studies indicate that CS1 may be regulated by a SAP-independent mechanism. In this study, we have examined the ligand specificity of CS1 and the effect of CS1 interaction with its ligand on the cytolytic activity of YT, a human NK cell line. Recombinant fusion protein, CS1-Ig, containing the CS1 extracellular domain and Fc portion of the human IgG bound cells transfected with CS1. CS1-Ig did not show any binding to cells expressing other members of the CD2 family. The cytolytic activity of YT was enhanced in presence of soluble CS1-Ig fusion protein. These results demonstrate that CS1 is a self-ligand and homophilic interaction of CS1 regulates NK cell cytolytic activity.
authors.affiliation: Department of Molecular Biology and Immunology, Institute for Cancer Research, University of North Texas, Health Science Center 3500, Fort Worth 76017, USA.
authors.forename: Pappanaicken R
authors.initials: PR
authors.lastname: Kumaresan
authors.forename: Wayne C
authors.initials: WC
authors.lastname: Lai
authors.forename: Samuel S
authors.initials: SS
authors.lastname: Chuang
authors.forename: Michael
authors.initials: M
authors.lastname: Bennett
authors.forename: Porunelloor A
authors.initials: PA
authors.lastname: Mathew
mesh_terms: D020816:Amino Acid Motifs; D002460:Cell Line; D003602:Cytotoxicity, Immunologic; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology*; D011971:Receptors, Immunologic / Q000737:chemistry / Q000276:immunology / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D000071176:Signaling Lymphocytic Activation Molecule Family
chemical_list: D011971:Receptors, Immunologic; D011993:Recombinant Fusion Proteins; C448987:SLAMF7 protein, human; D000071176:Signaling Lymphocytic Activation Molecule Family