Neutrophil CD44 rafts and rolls.

摘要

In this issue of Blood, Yago and colleagues identify CD44 and new components to an intracellular kinase signaling cascade in murine neutrophils that activates LFA-1 integrins, and thus enables E-selectin-mediated slow rolling. Functional E-selectin ligands identified on murine neutrophils include E-selectin ligand-1 (ESL-1), PSGL-1, and CD44. So far, PSGL-1 is the only ligand reported to support neutrophil slow rolling over inflamed venules. In this issue of Blood, Yago et al identify CD44 and new components to an existing intracellular kinase signaling cascade in neutrophils that activates LFA-1 integrins to enable E-selectin-mediated slow rolling. These studies report that E-selectin engagement of either CD44 or PSGL-1 in bone marrow leukocytes (> 90% neutrophils) triggered a sequential tyrosine kinase cascade consisting of (1) Src family kinases Hck, Lyn and Fgr, (2) Syk, (3) Btk, and (4) p38, and led to LFA-1 engagement of ICAM-1 (see figure) for slow rolling in vivo and in vitro.