What causes lupus?

The immune system is the body’s defense system. A healthy immune system protects the body by making antibodies (blood proteins) that attack foreign germs and cancers. With lupus, the immune system misfires and produces antibodies that attack healthy tissue. As the attack goes on, other immune cells join the fight. This leads to inflammation and abnormal blood vessels (vasculitis). These antibodies then end up in cells in organs, resulting in further damage.

The exact reason for this autoimmune response is not clear. It most likely results from a mix of inherited tendencies and things in your environment. These include viruses, sunlight and drug allergies. People with lupus may also have an impaired process for clearing old and damaged cells from the body, which causes an abnormal immune response.