CD44-chondroitin sulfate interactions mediate leukocyte rolling under physiological flow conditions

CD44 on leukocytes binds to its glycosaminoglycan (GAG) ligand, hyaluronic acid, and mediates the rolling of leukocytes on vascular endothelial cells. We previously reported that the recombinant CD44 protein binds to other GAGs, including chondroitin sulfates (CS), although the physiological significance of this interaction has remained unclear. Here we report that the CD44 expressed on mouse lymphoma BW5147 cells supports cell binding to immobilized CS under static conditions and mediates cell rolling in CS-coated glass capillary tubes under shear stresses ranging from 0.5 to 1.5 dyn/cm(2), which is within the physiological range of forces in venules. Both interactions were completely inhibited by pretreating the cells with an anti-CD44 antibody or by pretreating the CS with chondroitinase ABC, but not hyaluronidase. To address the role of the CD44-CS interaction in vivo, we examined the tissue localization of the CS that interacts with CD44. Interestingly, a recombinant CD44 fusion protein bound to hepatic sinuosoidal endothelial cells where CS was also expressed, as assessed by immunohistochemistry. These findings support the involvement of the CD44-CS interaction in the primary adhesion of lymphocytes to endothelial cells and raise the possibility that this interaction plays a role in the capture of CD44-positive cells, such as activated T cells and certain tumor cells, by the hepatic sinusoidal vasculature.