Molecules called toll-like receptors sit on the surface of human cells, always ready to start a reaction against bacteria and other invaders. When activated, the receptors call in a posse of immune system cells and proteins that take a shoot-first-and-ask-questions-later approach to strangers (SN: 9/8/01, p. 152: Immunity's Eyes). Researchers now report that in certain people, one of these signaling molecules, toll-like receptor 4, is not so trigger-happy.
The scientists report in the July 18 New England Journal of Medicine that people carrying the gene for this version of the receptor seem to generate less inflammation as they rev up an immune response than do people who harbor the garden-variety gene for toll-like receptor 4.
The upshot is both bad and good news for the people with the gene variant. They appear to have a weaker front-line defense against infection but seem less prone to heart disease than people with the normal gene