Understanding Lupus Lupus is a long-lasting autoimmune disease where the body's immune system attacks its own cells, causing damage. This disease can affect many parts of the body, including the joints, skin, kidneys, blood cells, brain, heart, and lungs. Lupus is often hard to diagnose because its symptoms are similar to those of other illnesses. One common sign of lupus is a butterfly-shaped rash on the face, but not everyone...