Inflammation is a process in which the body's white blood cells and chemicals protect us from infection and or foreign substances such as bacteria and viruses that often invade the body.... but in some disorders the body's defense system triggers an inflammatory response when there are no foreign substances to fight off... these particular disorders are called autoimmune diseases and they allow the body's normal protective immune system to cause damage to its own tissues (the body responds as if normal tissues are infected or abnormal)... as seen in RA and many other autoimmune diseases.