Expression of VLA-4 on eosinophils decreases in patients with eosinophilia

Background: It is assumed that the very late antigen-4 (VLA-4) plays a key role in selective migration and accumulation of eosinophils to the allergic inflammatory focus. The regulatory mechanism for VLA-4 expression is poorl y understood, as is its relationship between other adhesion molecules. Obje ctive: The aim of the study was to elucidate the relationship between VLA-4 expression and the activation of eosinophils. Methods: The surface express ion of VLA-4, Mac-1, ICAM-1, CD4, CD25, CD69, CD89, IL-5 receptor and GM-CS F receptor on eosinophils isolated from the peripheral blood of 15 patients with eosinophilia and 16 healthy volunteers was measured. Results: The sur face expression of VLA-4 presented in mean fluorescent intensity by flow-cy tometric analysis showed a significant decrease in the patients with eosino philia (>700 eosinophils/mul) compared to that of the subjects without eosi nophilia. On the other hand, the surface expression of Mac-1 was significan tly increased in the patients with eosinophilia. There was an inverse corre lation between the expression of VLA-4 and that of Mac-1 (r = -0.81) on the eosinophils obtained from the patients with eosinophilia. Conclusion: The changes on the surface expressions of Mac-1 and VLA-4 may be indicating the activation of eosinophils in the patients with eosinophilia and may contri bute to their migration to the allergic inflammatory focus. Copyright (C) 2 001 S. Karger AG, Basel.