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Brief Definitive Reports |
dβ2 Integrin Is Expressed on Human Eosinophils and Functions as an Alternative Ligand for Vascular Cell Adhesion Molecule 1 (VCAM-1)




ICOS Corporation, Bothell, Washington 98021
The β2 family of integrins, CD11a, CD11b, CD11c, and
d, are expressed on most leukocytes. We show that the newest member of this family,
d, is expressed on human eosinophils in peripheral blood, and surface expression can be upregulated within minutes by phorbol ester or calcium ionophore A23187. Culture of eosinophils with interleukin 5 (IL-5) leads to a two- to fourfold increase in
d levels by 3–7 d without a change in
4 integrin expression. Eosinophils isolated from late phase bronchoalveolar lavage fluids express
d at levels similar to that seen after 3 d of IL-5 culture. Regarding
dβ2 ligands, in both freshly isolated and IL-5–cultured eosinophils, as well as
dβ2-transfected Chinese hamster ovary cells,
dβ2 can function as a ligand for vascular cell adhesion molecule 1 (VCAM-1). This conclusion is based on the ability of monoclonal antibodies to
d, β2, or VCAM-1 to block cell attachment in static adhesion assays. In experiments with eosinophils, the relative contribution of
dβ2 integrin– mediated adhesion is enhanced after IL-5 culture. These experiments demonstrate that
dβ2 is an alternative ligand for VCAM-1, and this integrin may play a role in eosinophil adhesion to VCAM-1 in states of chronic inflammation.
Key Words: β2 integrin eosinophil adhesion vascular cell adhesion molecule 1
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