Lymphocytes rolling on high endothelial venules stop abruptly in response to chemokines presented by endothelial cells, according to a report published online in
Ronen Alon, of the Weizmann Institute of Science, Rehovot, Israel, and colleagues found that chemokines trigger instantaneous extension of the LFA-1 integrin—an adhesion molecule that can change between an inactive, bent conformation and an active, extended conformation. "The chemokine-mediated extension generates an intermediate affinity form of LFA-1, which brings the integrin head piece into close proximity with the adhesion molecule ICAM-1," Alon told
The physiological and biochemical data that the authors present argues for an integrin activation that happens in 0.1 to 0.5 seconds, resulting in a sudden arrest. "For a long time, it was believed that cells are rolling and ...
