The C-C chemokine MCP-1 differentially modulates the avidity of beta 1 and beta 2 integrins on T lymphocytes.

The ability of chemokines, particularly MCP-1, to induce integrin-dependent binding of T lymphocytes to endothelial adhesion molecules or extracellular matrix (ECM) components was examined. MCP-1 induced significant adhesion to fibronectin (FN) and to endothelial-secreted ECM but not to purified ICAM-1 or VCAM-1, or to activated endothelium. The MCP-1-induced binding of T lymphocytes to FN was rapid, dose dependent, and resulted from activation of both VLA-4 and VLA-5. Like MCP-1, the chemokines RANTES and MIP-1 beta induced T lymphocyte binding to FN, but not to ICAM-1. We suggest therefore, that these T lymphocyte chemokines may be most important, not in initiating integrin-dependent firm adhesion of T lymphocytes to the vascular wall, but rather, in subsequent adhesive interactions during migration into tissue.