An interesting example of how immune therapies can eliminate or reduce some of the ways in which the aging body damages itself: "Cholesterol is transported in the blood in LDL particles, which are a kind of fat drops that can accumulate in the walls of blood vessels. LDL activates the immune defence and triggers an inflammation in the blood vessels that leads to atherosclerosis (also known as arteriosclerosis). When the atherosclerotic plaque finally ruptures, a blood clot is formed that in turn can cause a heart attack or stroke. It was previously thought that the inflammation in the blood vessels arises when the T cells react to oxidised LDL particles located in the atherosclerotic plaque. Now, however, [researchers have found] that the opposite is true, namely that the T cells react to components in the normal LDL particles, and that they no longer recognise LDL once it has been oxidised. ... Since reactions to LDL can be dangerous, T cells are normally held in check by inhibitory signals. The body's own control works well as long as the LDL keeps to the blood, liver and lymph glands. But when it accumulates in the artery wall, this inhibition is no longer enough, the T cells are activated and an inflammation arises. ... Vaccination against the receptor that the T cells use to recognise LDL can block the immune reaction and reduce the disease by between 60 and 70 per cent."