Lyn, Jak2, and Raf-1 kinases are critical for the antiapoptotic effect of interleukin 5, whereas only Raf-1 kinase is essential for eosinophil activation and degranulation

Konrad Pazdrak, Barbara Olszewska-Pazdrak, Susan Stafford, Roberto P. Garofalo, Rafeul Alam

Research output: Contribution to journalArticle

140 Scopus citations


Interleukin (IL)-5 has been shown to activate many signaling molecules in eosinophils, but their functional relevance remains unknown. We have examined the functional relevance of Lyn, Jak2, and Raf-1 kinases in eosinophil survival, upregulation of adhesion molecules and degranulation. To this goal we used Lyn and Raf-1 antisense (AS) oligodeoxynucleotides (ODN) to inhibit the expression of these proteins and tyrphostin AG490 to specifically block the activation of Jak2. We have demonstrated that all three kinases are important for IL-5-induced suppression of eosinophil apoptosis. However, Lyn and Jak2 tyrosine kinases are not important for the upregulation of CD11b and the secretion of eosinophil cationic protein. In contrast, Raf-1 kinase is critical for both these functions. This is the first identification of specific signaling molecules responsible for three important functions of eosinophils. We have established a central role for Raf-1 kinase in regulating eosinophil survival, expression of β2 integrins and degranulation. Further, there appears to be a dissociation between two receptor-associated tyrosine kinases, i.e., Lyn and Jak2, and the activation of Raf-1 kinase. The delineation of the functional relevance of signaling molecules will help design therapeutic approaches targeting specific eosinophil function.

Original languageEnglish (US)
Pages (from-to)421-429
Number of pages9
JournalJournal of Experimental Medicine
Issue number3
StatePublished - Aug 3 1998



  • Degranulation
  • Eosinophil
  • Interleukin 5
  • Raf-1 kinase
  • Signal transduction

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

Cite this