title: CD200 is a ligand for all members of the CD200R family of immunoregulatory molecules.
abstract: CD200Fc, a chimeric molecule including the extracellular domain of CD200 and a murine IgG2a Fc region, regulates immune responses following engagement of a cell surface receptor, CD200R, expressed on cells of the myeloid and T cell lineage. A recent report focused attention on a family of CD200Rs, but concluded that only one member used CD200 as its ligand. We have also cloned and sequenced a family of CD200Rs, but identify an amino terminus to two of the three isoforms not recognized by previous researchers. We show by FACS, using FITC-labeled CD200Fc, that COS7 cells transfected with all CD200R isoforms bind CD200 as ligand, although the functional consequences of this binding likely differs between the different isoforms. mAbs directed against the CD200 R1/R4 isoforms altered IL-2/IL-4 cytokine production and suppressed CTL responses in a fashion comparable to CD200Fc, with a significantly lesser effect seen following addition of anti-CD200 R2/R3.
authors.affiliation: Transplant Research Division, Toronto Hospital, 200 Elizabeth Street, Toronto, Ontario M5G 2C4, Canada. reg.gorczynski@utoronto.ca
authors.forename: Reginald
authors.initials: R
authors.lastname: Gorczynski
authors.forename: Zhiqi
authors.initials: Z
authors.lastname: Chen
authors.forename: Yu
authors.initials: Y
authors.lastname: Kai
authors.forename: Lydia
authors.initials: L
authors.lastname: Lee
authors.forename: Simon
authors.initials: S
authors.lastname: Wong
authors.forename: Philip A
authors.initials: PA
authors.lastname: Marsden
mesh_terms: D000276:Adjuvants, Immunologic / Q000737:chemistry / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD; D000954:Antigens, Surface / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D003001:Cloning, Molecular; D007376:Interleukin-2 / Q000096:biosynthesis; D015847:Interleukin-4 / Q000096:biosynthesis; D008024:Ligands; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D064446:Orexin Receptors; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D011956:Receptors, Cell Surface; D016415:Sequence Alignment; D013602:T-Lymphocytes, Cytotoxic
chemical_list: D000276:Adjuvants, Immunologic; D015703:Antigens, CD; D000954:Antigens, Surface; C501103:Cd200r1 protein, mouse; D007376:Interleukin-2; D008024:Ligands; D064446:Orexin Receptors; D020033:Protein Isoforms; D011956:Receptors, Cell Surface; D015847:Interleukin-4; C042739:antigens, CD200