The impact of c-met/scatter factor receptor on dendritic cell migration.

Dendritic cells (DC) are professional antigen-presenting cells that possess both migratory properties and potent T cell stimulatory activity, and that allow the uptake of antigenic material inperipheral tissues and its subsequent presentation in the T cell areas of lymphoid organs. Thus motility represents a central property that is required for DC function. Here we report on the expression of the receptor tyrosine kinase c-met in DC. c-Met is the high affinity receptor for scatter factor (SF)/hepatocyte growth factor, and ligand-activated c-met exhibits mitogenic, morphogenic andmotogenic activity in vivo and in vitro. c-Met is signaling competent in DC since it is effectively tyrosine phosphorylated in response to SF ligand. It is demonstrated here that ligand-activated c-met regulates DC adhesion to the extracellular matrix component laminin but leaves antigen presenting function unaffected. Importantly, in ear sheet explant experiments activationof c-met by ligand induces emigration of cutaneous DC (Langerhans cell, LC) from skin, but SF is not a chemoattractant factor for DC. Our results suggest an important role of the c-met/SF system in DC/LC migration.