Characterization of the integrin and activation steps mediating human eosinophil and neutrophil adhesion to chronically inflamed airway endothelium.

We have used the Stamper-Woodruff frozen-section assay (FSA) to characterize the integrin and activation steps involved in adhesion of peripheral blood eosinophils and neutrophils to nasal polyp endothelium (NPE). Eosinophil and neutrophil adhesion was significantly inhibited by monoclonal antibodies (mAbs) against CD18 (beta2) and CD11a-c. Eosinophil adhesion was also inhibited to a lesser extent by mAbs against CD29 (beta1), CD49d (alpha4), and vascular cell adhesion molecule-1. The involvement of integrins raised the possibility of an activation step being involved in the adhesion process. Although stimulation of the cells with granulocyte macrophage colony-stimulating factor (GM-CSF) before the assay failed to modulate adhesion, binding was inhibited by up to 50% by treatment of the leukocytes with azide. In addition, neutrophil adhesion was completely abrogated by pertussis toxin (PT) and inhibited by about 50% by the platelet-activating factor antagonist WEB 2086 and antibodies against interleukin (IL)-8 and the two IL-8 receptors IL8RA and IL8RB (C-X-CR1 and -CR2). In contrast, eosinophil adhesion was unaffected by PT, WEB 2086, or anti-IL8R mAbs. mAbs against CCR-3, IL-3, IL-5, and GM-CSF also had no effect. This study demonstrates that eosinophil and neutrophil adhesion to NPE in the FSA conforms to the multistep paradigm for leukocyte adhesion and can be used to model the molecular basis for adhesion to endothelium in the context of chronic inflammatory disease. Using this assay, we have observed significant differences in integrin usage between eosinophils and neutrophils and a striking difference in the mechanism of integrin activation. These differences could explain, in part, the preferential accumulation of eosinophils in diseases such as asthma.