Cross-linking of CD18 primes human neutrophils for activation of the respiratory burst in response to specific stimuli: implications for adhesion-dependent physiological responses in neutrophils

J Leukoc Biol. 1995 Dec;58(6):690-7. doi: 10.1002/jlb.58.6.690.


Adhesion is known to prime neutrophils for physiological activation in response to cytokines and other stimuli. We have employed the technique of receptor cross-linking to study the potential role of CD18, the common beta-subunit of the beta 2-integrin family of adhesion molecules, in the regulation of the respiratory burst, as measured by luminol-enhanced chemiluminescence and iodination, in human neutrophils. CD18 cross-linking primed neutrophils to activate the respiratory burst after stimulation with tumor necrosis factor alpha (TNF-alpha) (100 units/mL), formylmethionyl-leucyl-phenylalanine (fMLP) (1 microM), and granulocyte-macrophage colony-stimulating factor (GM-CSF) (1 micrograms/mL), but not granulocyte colony-stimulating factor (G-CSF) (1 micrograms/mL), interferon-gamma (IFN-gamma) (100 U/mL), or phorbol myristate acetate (100 nM). The maximal rate of chemiluminescence induced by fMLP, TNF-alpha, and GM-CSF was enhanced 8-, 6-, and 1.5-fold, respectively, following CD18 cross-linking. Priming of the respiratory burst by direct engagement of CD18 was confirmed in neutrophil-mediated iodination experiments, where iodination induced by TNF-alpha, fMLP, and GM-CSF was increased 15-, 20-, and 7-fold, respectively, by CD18 cross-linking. Immunoblot experiments demonstrated that TNF-alpha-induced tyrosine phosphorylation was both accelerated and more intense in neutrophils after cross-linking of CD18. Major tyrosine phosphoprotein products include proteins with approximate molecular masses of 40, 70, and 110 kDa. Genistein (50 microM), a selective tyrosine kinase inhibitor, reduced the TNF-alpha-stimulated respiratory burst by > 80% whether or not CD18 was cross-linked. These results affirm the importance of CD18 in adhesion-dependent priming of neutrophil functions and demonstrate that CD18 engagement per se is sufficient to prime neutrophils for cytokine-induced signal transduction mediated by tyrosine phosphorylation.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • CD18 Antigens / physiology*
  • Cell Adhesion
  • Genistein
  • Granulocyte-Macrophage Colony-Stimulating Factor / pharmacology
  • Humans
  • Isoflavones / pharmacology
  • Leukocyte Common Antigens / physiology
  • N-Formylmethionine Leucyl-Phenylalanine / pharmacology
  • Neutrophil Activation*
  • Neutrophils / physiology*
  • Phosphorylation
  • Respiratory Burst*
  • Signal Transduction
  • Tumor Necrosis Factor-alpha / pharmacology
  • Tyrosine / metabolism


  • CD18 Antigens
  • Isoflavones
  • Tumor Necrosis Factor-alpha
  • Tyrosine
  • N-Formylmethionine Leucyl-Phenylalanine
  • Granulocyte-Macrophage Colony-Stimulating Factor
  • Genistein
  • Leukocyte Common Antigens