Calcium increases the appetite

Neutrophils are gluttonous little cells—they will engulf just about any small particle that comes their way. But eating up an entire bacterium takes significant effort. On page 181, Dewitt and Hallett report that neutrophils need integrins and a Ca²⁺ boost to build a mouth that is up to the task.

Phagocytosis around a particle occurs in a series of steps that includes pseudopodial formation of a phagocytic cup and cup closure/retraction. When microbes present complement components, which are the targets for integrin binding, the phagocytic cups close around the bugs more rapidly. The authors found that this speediness correlated with a sequence of Ca²⁺ changes during both cup formation and closure. At cup formation, complement binding to integrin initiated the release of local Ca²⁺ stores near the contact site....