Circulating lymphocytes are recruited from the blood to the tissue by rolling along the endothelium until being stopped by a signaling event linked to the Gialpha subunit of a heterotrimeric GTP-binding protein; that event then triggers rapid integrin-dependent adhesion. Four chemokines are now shown to induce such adhesion to intercellular adhesion molecule-1 and to induce arrest of rolling cells within 1 second under flow conditions similar to those of blood. SDF-1 (also called PBSF), 6-C-kine (also called Exodus-2), and MIP-3beta (also called ELC or Exodus-3) induced adhesion of most circulating lymphocytes, including most CD4+ T cells; and MIP-3alpha (also called LARC or Exodus-1) triggered adhesion of memory, but not naïve, CD4+ T cells. Thus, chemokines can regulate the arrest of lymphocyte subsets under flowing conditions, which may allow them to control lymphocyte-endothelial cell recognition and lymphocyte recruitment in vivo.

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