Distinct Phenotypic Adhesion Molecule Expression on Human Cord Blood Progenitors During Early Eosinophilic Commitment: Upregulation of β7 Integrins

Increasing levels of proinflammatory cells, including eosinophils and basophils, are seen at the site of allergen challenge in allergic disease of the airways. Mechanisms for the recruitment of these cell types could involve either specific upregulation of adhesion molecule and chemoattraction, or the initiation of proliferation and differentiation of inflammatory cell progenitors derived from the bone marrow. In this study, we demonstrate, in two systems of eosinophilic-basophilic lineage-committed granulocytes of relative immaturity, that eosinophilic differentiation in vivo implies the induction of a distinct adhesion phenotype, characterized by the upregulation of beta(7) integrin and downregulation of beta(1) and alpha(5) integrins. Moreover, the eosinophilic differentiation induced an upregulation of complement receptor type 1 and type 3, and the expression was further enhanced upon a short-course in vitro activation with ionomycin. These data indicate a sequential alteration of disparate members of the integrin family during eosinophilic-basophilic differentiation, which may attribute to specific adhesion requirements at distinct stages of cell maturation.