Rheumatoid arthritis (RA) is an inflammatory disease of the joints. Atherosclerosis is an inflammatory disease, as well. Research over the past 35 years has shown that cholesterol accumulation in the blood vessel wall causes an inflammatory reaction. A "clean-up crew" of white blood cells infiltrates the vessel wall. Some of those cells, called macrophages, engulf as much cholesterol as possible, becoming "foam cells" in the process. These foam cells often explode, and the process starts all over again. Additionally, the activity of inflammatory cells (though well-intentioned) can often lead to instability of the atherosclerotic plaque, leading to rupture. Unstable angina or myocardial infarction (heart attack) can be the result of such plaque rupture, when the bloodstream touches this "sticky" material inside the plaque.