Systemic lupus erythematosus (SLE) is an autoimmune disease that causes inflammation of joints, tendons, skin, blood vessels and other connective tissue, and organs. SLE causes the immune system to produce antibodies that attack the body's healthy cells and tissue. Of all the forms of lupus, SLE is the most common and most well-known.

The cause of SLE is unknown. It is likely due to a combination of genetic and environmental factors.