Cloning, mapping, and characterization of activated leukocyte-cell adhesion molecule (ALCAM), a CD6 ligand

J Exp Med. 1995 Jun 1;181(6):2213-20. doi: 10.1084/jem.181.6.2213.


Antibody-blocking studies have demonstrated the role of CD6 in thymocyte-thymic epithelial (TE) cell adhesion. Here we report that CD6 expressed by COS cells mediates adhesion to TE cells and that this interaction is specifically blocked with an anti-CD6 monoclonal antibody (mAb) or with a mAb (J4-81) that recognized a TE cell antigen. We isolated and expressed a cDNA clone encoding this antigen and show that COS cells transfected with this cDNA bind a CD6 immunoglobulin fusion protein (CD6-Rg). This antigen, which we named ALCAM (activated leukocyte-cell adhesion molecule) because of its expression on activated leukocytes, appears to be the human homologue of the chicken neural adhesion molecule BEN/SC-1/DM-GRASP. The gene was mapped to human chromosome 3q13.1-q13.2 by fluorescence in situ hybridization of cDNA probes to metaphase chromosomes. We prepared an ALCAM-Rg fusion protein and showed that it binds to COS cell transfectants expressing CD6, demonstrating that ALCAM is a CD6 ligand. The observations that ALCAM is also expressed by activated leukocytes and that both ALCAM and CD6 are expressed in the brain suggest that ALCAM-CD6 interactions may play a role in the binding of T and B cells to activated leukocytes, as well as in interactions between cells of the nervous system.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Activated-Leukocyte Cell Adhesion Molecule
  • Amino Acid Sequence
  • Animals
  • Antigens, CD / metabolism*
  • Antigens, Differentiation, T-Lymphocyte / metabolism*
  • Cell Adhesion
  • Cell Adhesion Molecules / biosynthesis
  • Cell Line
  • Chlorocebus aethiops
  • Chromosome Banding
  • Chromosome Mapping
  • Chromosomes, Human, Pair 3*
  • Consensus Sequence
  • Epithelial Cells
  • Epithelium / physiology
  • Glycoproteins / biosynthesis*
  • Glycoproteins / genetics
  • Glycoproteins / metabolism
  • Humans
  • Karyotyping
  • Ligands
  • Molecular Sequence Data
  • Recombinant Fusion Proteins / biosynthesis
  • Sequence Homology, Amino Acid
  • T-Lymphocytes / cytology
  • T-Lymphocytes / immunology
  • Thymus Gland / cytology
  • Thymus Gland / physiology
  • Transfection
  • Tumor Cells, Cultured


  • Activated-Leukocyte Cell Adhesion Molecule
  • Antigens, CD
  • Antigens, Differentiation, T-Lymphocyte
  • CD6 antigen
  • Cell Adhesion Molecules
  • Glycoproteins
  • Ligands
  • Recombinant Fusion Proteins

Associated data

  • GENBANK/L38608