title: ICAM, an adhesion ligand of LFA-1, is homologous to the neural cell adhesion molecule NCAM.
abstract: Antigen-specific cell contacts in the immune system are strengthened by antigen-nonspecific interactions, mediated in part by lymphocyte-function associated (LFA) antigens. The LFA-1 antigen is widely expressed on cells of haematopoietic origin and is a major receptor of T cells, B cells and granulocytes. LFA-1 mediates the leukocyte adhesion reactions underlying cytolytic conjugate formation, helper T-cell interactions, and antibody-dependent killing by natural killer cells and granulocytes. Recently, ICAM-1 (intercellular adhesion molecule-1) has been defined as a ligand for LFA-1. Monoclonal antibodies to ICAM-1 block T lymphocyte adhesion to fibroblasts and endothelial cells and disrupt the interaction between cytotoxic T cells and target cells. In addition, purified ICAM-1 reconstituted into artificial membranes binds LFA-1+ cells. ICAM-1 is found on leukocytes, fibroblasts, epithelial cells and endothelial cells and its expression is regulated by inflammatory cytokines. LFA-1 has been placed in the integrin family of cell surface receptors by virtue of the high sequence similarity between the LFA-1 and integrin beta chains. The adhesion ligands of the integrin family are glycoproteins bearing the Arg-Gly-Asp (RGD) sequence motif, for example, fibronectin, fibrinogen, vitronectin and von Willebrand factor. Here we show that a complementary DNA clone ICAM-1 contains no RGD motifs, but instead is homologous to the neural cell adhesion molecule NCAM.
authors.affiliation: Department of Molecular Biology, Harvard Medical School, Massachusetts General Hospital, Boston 02114.
authors.forename: D
authors.initials: D
authors.lastname: Simmons
authors.forename: M W
authors.initials: MW
authors.lastname: Makgoba
authors.forename: B
authors.initials: B
authors.lastname: Seed
mesh_terms: D000595:Amino Acid Sequence; D000954:Antigens, Surface / Q000235:genetics*; D001483:Base Sequence; D015815:Cell Adhesion Molecules; D004247:DNA / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid
chemical_list: D000954:Antigens, Surface; D015815:Cell Adhesion Molecules; D011994:Recombinant Proteins; D004247:DNA