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The human S100 protein MRP-14 is a novel activator of the beta 2 integrin Mac-1 on neutrophils

R A Newton1, N Hogg

  • 1Leukocyte Adhesion Laboratory, Imperial Cancer Research Fund, London, United Kingdom.

Journal of Immunology (Baltimore, Md. : 1950)
|May 7, 1998
PubMed

Insights

Myeloid-related protein-14 (MRP-14) stimulates neutrophil adhesion by regulating the beta 2 integrin Mac-1. MRP-8 inhibits this effect, and MRP-14 signals through a G protein-dependent pathway, suggesting roles in neutrophil adhesion regulation.

Area of Science:

  • Immunology
  • Cell Biology
  • Biochemistry

Background:

  • Myeloid-related protein-14 (MRP-14) and MRP-8 are abundant S100 calcium-binding proteins in neutrophils.
  • Previous studies indicated extracellular roles for these proteins in leukocyte transmigration.

Purpose of the Study:

  • To investigate the function of MRP-14 in neutrophil adhesion.
  • To elucidate the mechanism by which MRP-14 regulates integrin function.

Main Methods:

  • Assessed neutrophil adhesion using soluble ligand binding and activation reporter epitope expression.
  • Investigated the role of MRP-8 in MRP-14 activity.
  • Determined the signaling pathway involved in MRP-14-mediated adhesion using pertussis toxin.

Main Results:

  • MRP-14 stimulates neutrophil adhesion via the beta 2 integrin Mac-1, acting as an affinity regulator.
  • MRP-14 does not induce L-selectin release, respiratory burst, or calcium flux, indicating specific integrin regulation.
  • MRP-8 inhibits MRP-14-induced adhesion by forming a heterodimer.
  • MRP-14 signals through a pertussis toxin-sensitive, G protein-dependent pathway, not by direct Mac-1 binding.

Conclusions:

  • MRP-14 is a novel stimulator of neutrophil adhesion through Mac-1 affinity regulation.
  • MRP-8 modulates MRP-14 activity, and the signaling pathway involves G proteins.
  • MRP-14 and MRP-8 are proposed as key in vivo regulators of neutrophil adhesion via Mac-1 control.

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