Lupus is an autoimmune disease. The immune system's job is to fight foreign substances in the body, such as germs and viruses. But in autoimmune diseases, the immune system attacks healthy tissues, not germs.
Lupus is a disease that can affect many parts of the body. Lupus can involve the joints, the skin, the kidneys, the lungs, the heart, and/or the brain. If you have lupus, it may affect several parts of your body. Usually, one person doesn't have all the possible symptoms.