Molecular and functional analysis of human natural killer cell-associated neural cell adhesion molecule (N-CAM/CD56)

J Immunol. 1991 Jun 15;146(12):4421-6.

Abstract

The neural cell adhesion molecule (N-CAM/CD56) is a member of the Ig supergene family that has been shown to mediate homophilic binding. Several isoforms of N-CAM have been identified that are expressed preferentially in different tissues and stages of embryonic development. To examine the primary structure of N-CAM expressed in leukocytes, N-CAM cDNA were generated by polymerase chain reaction from RNA isolated from normal human NK cells and the KG1a hematopoietic leukemia cell line. The sequence of leukocyte-derived N-CAM cDNA was essentially identical with N-CAM cDNA from human neuroblastoma cells that encode the 140-kDa isoform of N-CAM. Inasmuch as N-CAM is preferentially expressed on human NK cells and a subset of T lymphocytes that mediate MHC-unrestricted cell-mediated cytotoxicity, we examined the potential role of N-CAM in cell-mediated cytotoxicity and heterotypic lymphocyte-tumor cell adhesion. N-CAM loss mutants were established from the human N-CAM+ KG1a leukemia cell line, and N-CAM cDNA was transfected into a human colon carcinoma cell line and murine L cells. Using this panel of mutants and transfectants, it was determined that expression of N-CAM on these target cells does not affect susceptibility to resting or IL-2-activated NK cell-mediated cytotoxicity. Moreover, expression of N-CAM in these transfectants failed to induce homotypic or heterotypic cellular adhesion. Collectively, these studies indicate that homophilic N-CAM interactions probably do not mediate a major role in the cytolytic interaction between NK cells and N-CAM+ tumor cell targets.

MeSH terms

  • Antigens, CD / physiology*
  • Antigens, Differentiation, T-Lymphocyte / genetics
  • Antigens, Differentiation, T-Lymphocyte / physiology*
  • Base Sequence
  • CD56 Antigen
  • Cell Adhesion Molecules, Neuronal / genetics
  • Cell Adhesion Molecules, Neuronal / physiology*
  • Cytotoxicity, Immunologic
  • DNA / analysis
  • Humans
  • Killer Cells, Natural / immunology*
  • Molecular Sequence Data
  • Transfection

Substances

  • Antigens, CD
  • Antigens, Differentiation, T-Lymphocyte
  • CD56 Antigen
  • Cell Adhesion Molecules, Neuronal
  • DNA