Adherence of eosinophils from allergic and normal ponies to cultured equine endothelial cells

Objectives: To compare adherence of stimulated and unstimulated eosinophils from allergic and normal ponies to cultured equine vascular endothelial ce lls (equine digital vein endothelial cells, EDVEC) and examine the effect o f eosinophil-derived factor(s) on cell adherence. Methods: Eosinophil adherence to unstimulated EDVEC or EDVEC pretreated wit h IL-1 beta or supernatants from stimulated eosinophils was measured. Super natants were also assayed for TNF alpha and IL-1 alpha -like bioactivity. Results: Adherence of unstimulated and rhIL-5 (10 ng/ml)-stimulated eosinop hils from allergic ponies to rhIL-1 beta -treated EDVEC was significantly g reater than that of cells from normal ponies. Pretreatment of EDVEC with su pernatants from stimulated eosinophils from both groups of ponies significa ntly increased adherence of autologous cells and IL-1 beta- and TNF alpha - like bioactivities were detected in the supernatants. Conclusions: Mediator-induced activation of equine eosinophils may lead to further eosinophil recruitment by releasing cytokines that up-regulate endo thelial cell adhesion molecule expression. Increased adherence of blood eos inophils from allergic ponies to stimulated endothelium could be explained by in vivo priming.