The role of CD47 in neutrophil transmigration - Increased rate of migration correlates with increased cell surface expression of CD47

CD47, a cell surface glycoprotein, plays an important role in modulating ne utrophil (PAIN) migration across endothelial and epithelial monolayers. Her e we show that anti-CD47 monoclonal antibodies (mAbs) delay PMN migration a cross collagen-coated filters or T84 epithelial monolayers toward the chemo attractant formylmethionylleucylphenylalanine (fMLP). Despite delayed trans migration by anti-CD47 mAbs, the numbers of PMN migrating across in either condition were the same as in the presence of control non-inhibitory m-Abs. Cell surface labeling and immunoprecipitation demonstrated upregulation of CD47 to the PMN cell surface with kinetics similar to those of the transmi gration response. Subcellular fractionation studies revealed redistribution of CD47 from intracellular compartments that co-sediment with secondary gr anules to plasma membrane-containing fractions after fMLP stimulation. Expe riments performed to investigate potential signaling pathways revealed that inhibition of tyrosine phosphorylation with genistein reversed the anti-CD 47-mediated PMN migration delay, whereas inhibition of phosphatidylinositol 3-kinase only partially reversed anti-CD47 effects that correlated with a rapid increase in PMN cell surface CD47. Analysis of the contribution of ep ithelial-expressed CD47 to PMN transmigration revealed that PMN migration a cross CD47-deficient epithelial monolayers (CaCO2) was significantly increa sed after stable transfection with CD47. These results suggest that cell su rface CD47 and downstream tyrosine phosphorylation signaling events regulat e, in part, the rate of PMN migration during the inflammatory response.