A "natural killer cell,'' (upper left, in green) the body's first line of defense against disease or infection, attacks a cancer cell (in blue), preparing to destroy it.
A "natural killer cell,'' (upper left, in green) the body's first line of defense against disease or infection, attacks a cancer cell (in blue), preparing to destroy it. Yokoyama laboratory, Washington University of St. Louis / MCT
A "natural killer cell,'' (upper left, in green) the body's first line of defense against disease or infection, attacks a cancer cell (in blue), preparing to destroy it. Yokoyama laboratory, Washington University of St. Louis / MCT

Some of your body's cells have a 'license to kill'

February 17, 2009 1:56 PM