CD11b/CD18-coated microspheres attach to E-selectin under flow

Neutrophils call attach to E-selectin under flow. Proposed ligands for E-selectin carry SLe(x)-type glycans. The leukocyte beta(2) integrins are glycosylated with SLe(x). Thus, we speculated that beta(2) integrins could support attachment to E-selectin. To test this hypothesis, we coated 10-mu m-diameter microspheres with purified CD11b/CD18 (alpha(M)beta(2)) and investigated the adhesion of the resulting alpha(M)beta(2) microspheres to E-selectin. Under in vitro flow conditions, the alpha(M)beta(2) microspheres attached to Chinese hamster ovary cells expressing E-selectin (CHO-E) and 4-h interleukin-1 beta-activated human umbilical vein endothelial cells (HUVEC), At a shear stress of 1.8 dynes/cm(2), the attachment events were eliminated by pretreatment of the cellular monolayers with a mAb to E-selectin. alpha(M beta 2) microspheres did not attach to untransfected CHO cells or unactivated HUVEC at 1.8 dynes/cm(2). Taken together, the results strongly suggest that the CD11b/CD18-E-selectin bond has sufficient biophysical properties to mediate attachment of neutrophil-sized particles to E-selectin under now.