CHEMOKINES Presentation of chemokine SDF-1a by fibronectin mediates directed migration of T cells

The role of chemokine–matrix interac-tions in integrin-dependent T-cell migra-tion was examined to address the critical question of how chemokines provide di-rectional information. The chemokine SDF-1a binds fibronectin (Fn) with a low nanomolar Kd (equilibrium dissociation constant). SDF-1a presented by Fn in-duced directed migration. Spatial concen-tration gradients of chemokine were not required to maintain directed migration. Fn-presented chemokine induced the po-larization of cells, including the redistribu-tion of the SDF-1a receptor, to the basal surface and leading edge of the cell. A new model for directed migration is pro-posed in which the co-presentation of an adhesive matrix and chemokine provides the necessary positional information inde-pendent of a soluble spatial gradient