'Outside-in' signalling mechanisms underlying CD11b/CD18-mediated NADPH oxidase activation in human adherent blood eosinophils

Oonagh T. Lynch, Mark A. Giembycz, Peter J. Barnes, Paul G. Hellewell, Mark A. Lindsay

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45 Citations (SciVal)


1. Incubation of human eosinophils in BSA-coated tissue culture plates resulted in time-dependent adhesion and attendant activation of the NADPH oxidase that were both inhibited (by > 85%) by blocking antibodies raised against CD11b and CD18. 2. SB 203580, an inhibitor of p38 mitogen-activated protein (MAP) kinase, did not influence adhesion but inhibited superoxide anion generation (pIC50 = -6.57). 3. PP1, an inhibitor of the src-family of protein tyrosine kinases, inhibited adhesion and CD11b/CD18-mediated superoxide anion generation with similar potencies (pEC50s = -5.53 and -5.99 respectively) suggesting that inhibition of the NADPH oxidase was a direct consequence of blocking adhesion. 4. The protein kinase C (PKC) inhibitors Ro-31 8220 (broad spectrum inhibitor), GF 109203X (inhibitor of conventional and novel isoforms) and Go 6976 (inhibitor of conventional isoforms) suppressed adhesion-dependent NADPH oxidase activation (pIC50s = -6.61, -6.05 and -4.89 respectively) without affecting adhesion. Based upon the selectivity of these drugs PRCδ and PKCε are implicated in the suppression of oxidant production. 5. Wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PtdIns 3-kinase), abolished superoxide anion production in adherent eosinophils (pEC50 = -9.06). Similarly, CD11b/CD18-dependent adhesion was suppressed with the same potency (pEC50 = -9.29) although the maximum effect did not exceed 50% implying that wortmannin also had an affect on those processes that govern adhesion-driven oxidase activation. 6. PD 098059 and piceatannol, inhibitors of MAP kinase kinase-1 and the syk tyrosine kinase respectively, had no effect on CD11b/CD18-mediated adhesion or NADPH oxidase activation. 7. The results of this study demonstrate that human eosinophils adhere to BSA-coated plastic by a CD11b/CD18-dependent mechanism, which is responsible for activation of the NADPH oxidase. Although the signalling pathway(s) utilized by CD11b/CD18 is still to be elucidated, the data presented herein implicate p38 MAP kinase, novel PKCs and PtdIns 3-kinase.

Original languageEnglish
Pages (from-to)1149-1158
Number of pages10
JournalBritish Journal of Pharmacology
Issue number6
Publication statusPublished - 30 Nov 1999


  • 'Outside-in' signalling
  • Adhesion (CD11b/CD18)-dependent NADPH oxidase activation
  • Human adherent eosinophils
  • p38 MAP kinase
  • Protein kinase C

ASJC Scopus subject areas

  • Pharmacology


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