Systemic Lupus Erythematosus (SLE) is a chronic, inflammatory, multisystem disorder of the immune system that mainly affects women of childbearing age. In SLE, the body develops antibodies that react against the person's own normal tissue. This abnormal response leads to the many manifestations of SLE and can be very damaging.

The course is unpredictable and individualized; no two patients are alike. Lupus is not contagious, infectious, or malignant. It usually develops in young women of childbearing years, but many men and children also develop lupus.

African Americans and Hispanics have a higher frequency of this disease than do Caucasians. SLE also appears in the first-degree relatives of lupus patients more often than it does in the general population, which indicates a strong hereditary component. However, most cases of SLE occur sporadically, indicating that both genetic and environmental factors play a role in the development of the disease.