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

The role of chemokine-matrix interactions in integrin-dependent T-cell migr ation was examined to address the critical question of how chemokines provi de directional information. The chemokine SDF-1 alpha binds fibronectin (Fn ) with a low nanomolar K-d (equilibrium dissociation constant). SDF-1 alpha presented by Fn induced directed migration. Spatial concentration gradient s of chemokine were not required to maintain directed migration. Fn-present ed chemokine induced the polarization of cells, including the redistributio n of the SDF-1 alpha receptor, to the basal surface and leading edge of the cell. A new model for directed migration is pro-posed in which the co-pres entation of an adhesive matrix and chemokine provides the necessary positio nal information independent of a soluble spatial gradient. (C) 2000 by The American Society of Hematology.