The mechanism by which neutrophils, the most abundant cell of the immune system, migrate and its consequence is revealed in a paper published online this week in Nature Immunology. Quantifying and controlling the migration pattern of neutrophils could have important implications for a wide variety of inflammatory diseases, such as stroke or trauma of damaged tissues that result from blood blockage.
Neutrophils actively migrate through the body and are generally the first white blood cell to appear at a site of infection. Looking at neutrophils in vivo, Sussan Nourshargh and colleagues found that these cells migrated readily from the vasculature into tissues. However, during certain kinds of inflammation they also migrated in reverse from tissues and back into the bloodstream under the influence of a blood vessel molecule called JAM-C. This kind of reverse migration had not been previously observed in mammals, and appeared to be responsible for disseminating inflammation throughout the body.