Dendritic cell, image courtesy of Wikimedia Commons/Judith Behnsen, et al.

Immune cells do more than just fend off infections. When cholesterol starts building up in arteries, scavenger white blood cells known as macrophages report to the scene to start trying to digest it. These little cells, though, don’t always manage to clear the site and often end up as part of the blockade themselves. These building plaques can restrict blood flow in the artery a precursor to a heart attack or dislodge and wind up in the brain leading to stroke .