Constitutively polarized granules prime KHYG-1 NK cells

Int Immunol. 2006 Sep;18(9):1347-54. doi: 10.1093/intimm/dxl071. Epub 2006 Jul 18.

Abstract

The major mechanism for NK cell lysis of tumor cells is granule-mediated cytotoxicity. Polarization of granules is a prelude to the release of their cytotoxic contents in response to target-cell binding. We describe the novel observation of constitutive granule polarization in the cytotoxic NK cell line, KHYG-1. Continuous degranulation of KHYG-1 cells, however, does not occur and still requires target-cell contact. Disruption of microtubules with colcemid is sufficient to disperse the granules in KHYG-1 and significantly decreases cytotoxicity. A similar effect is not obtained by inhibiting extracellular signal-related kinase 2 (ERK2), the most distal kinase investigated in the cytolytic pathway. Disruption of microtubules significantly down-regulates activation receptors, NKp44 and NKG2D, implicating them as potential microtubule-trafficking receptors. Such changes in upstream receptor expression may have caused deactivation of ERK2, since NKG2D cross-linking also leads to receptor down-regulation and diminished ERK phosphorylation. Thus, a functional role for NKG2D in KHYG-1 cytotoxicity is demonstrated. Moreover, the novel primed state may contribute to the high cytotoxicity exhibited by KHYG-1.

MeSH terms

  • Antineoplastic Agents, Phytogenic / pharmacology
  • Cell Line
  • Cytoplasmic Granules / drug effects
  • Cytoplasmic Granules / immunology*
  • Cytoplasmic Granules / metabolism
  • Cytotoxicity, Immunologic*
  • Demecolcine / pharmacology
  • Flow Cytometry
  • Humans
  • Immunoblotting
  • Immunohistochemistry
  • Killer Cells, Natural / immunology*
  • Killer Cells, Natural / metabolism
  • Microscopy, Confocal
  • Microtubules / drug effects
  • Mitogen-Activated Protein Kinase 1 / drug effects
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • NK Cell Lectin-Like Receptor Subfamily K
  • Natural Cytotoxicity Triggering Receptor 2
  • Protein Transport / drug effects
  • Protein Transport / physiology
  • Receptors, Immunologic / drug effects
  • Receptors, Immunologic / metabolism
  • Receptors, Natural Killer Cell

Substances

  • Antineoplastic Agents, Phytogenic
  • KLRK1 protein, human
  • NCR2 protein, human
  • NK Cell Lectin-Like Receptor Subfamily K
  • Natural Cytotoxicity Triggering Receptor 2
  • Receptors, Immunologic
  • Receptors, Natural Killer Cell
  • Mitogen-Activated Protein Kinase 1
  • Demecolcine