As anyone who has reacted to poison ivy can attest, the plant can induce maddeningly itchy skin. Researchers have now found that a cell once thought to be one of the chief perpetrators of this immune overreaction may actually keep the reaction from getting out of hand.
Mast cells make proteins that contribute to the inflammation that characterizes allergic reactions. The cells are part of the innate immune system, the frontline defense that rushes inflammatory cells and proteins to scenes of irritation or injury. Although mast cells play a valuable role in fighting bacteria and other pathogens, their conduct in allergic reactions appears rather like throwing gasoline on a fire.