Modulation of normal human eosinophil chemotaxis in vitro by herbimycin A, erbstatin and pervanadate

Background: The mediators involved in eosinophil accumulation in diseases such as allergy continue to be an area of interest, even though little is known regarding the signaling involved in the human cell type recruitment. In the present study, we demonstrate a novel modulatory role of tyrosine kinase and tyrosine phosphatase activities on normal human eosinophil chemotaxis induced by different groups of chemoattractant. Methods: Purified eosinophils were obtained from normal healthy volunteers with the CD16-negative procedure. Chemotactic activities against platelet-activating factor (PAF), vasoactive intestinal peptide (VIP) and eotaxin were assessed using a 48-well microchemotaxis chamber assay. Purified eosinophils were pretreated with herbimycin A, erbastatin or pervanadate to examine the role of tyrosine kinase in chemoattractant signaling. Results: Pretreatment of eosinophils with the tyrosine kinase inhibitors herbimycin A and erbstatin significantly blocked chemotaxis induced by eotaxin whilst both inhibitors augmented chemotaxis induced by VIP; however, they had no effect on PAF-induced chemotaxis. On the other hand, pretreatment of eosinophils with the phosphotyrosine phosphatase inhibitor pervanadate resulted in augmentation of eotaxin-induced chemotaxis and inhibition of VIP-induced chemotaxis, but it had no effect on PAF-induced chemotaxis. Conclusions: These results suggest that protein kinase plays a modulatory role in eosinophil chemotaxis induced by various chemoattractants.