"Inside all of us lurks an army of serial killers whose primary function is to kill again and again."
That might sound like something you'd hear in a movie preview. In fact, it's Prof. Gillian Griffiths, director of the Cambridge Institute for Medical Research in England, and she's talking not about science fiction but about a very real kind of immune system cell.
Known as cytotoxic T cells, these cellular assassins--each about one-tenth the thickness of a strand of human hair--are constantly patrolling our bodies, seeking out and destroying cells that are cancerous or infected with dangerous viruses.
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The time-lapse footage was created by stitching together microscopic slices of the killer cells and their quarry, according to a written statement released by the University of Cambridge. It shows T cells (orange or green blobs) encountering cancer cells (blue blobs) and injecting them with lethal proteins known as cytotoxins (red).