Systemic Lupus Erythematosus - Causes

Highlights	Complications	Lifestyle Changes
Introduction	Diagnosis	Resources
Causes	Treatment	References
Risk Factors	Treatment for Cutaneous and Mild SLE
Symptoms	Treatment for Severe SLE

Causes

Systemic lupus erythematosus is a complex disorder that occurs as a consequence of a number of independent processes and factors.

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Environmental factors, such as viruses, exposure to chemicals, or sunlight trigger inflammatory or immune activity. This immune activation may begin as an appropriate response to an unwanted "invader." But, because of a combination of genetic factors, an individual with lupus develops an ongoing immune response that does not shut itself off appropriately. This leads to waxing and waning flares of inflammation that can involve various organs of the body, depending on specific features of this self-perpetuating immune response in individual patients.

The exact combination of genes that predispose individuals to SLE may differ somewhat from patient to patient, but probably share certain common features which tend to impair the ability of the body to rid itself of immune-triggering particles and which tend to prolong or increase the degree of immune responsiveness to these triggers.

A major characteristic of lupus is that it is an autoimmune response, in which immune factors, called autoantibodies, seem to attack the person's own cells. Some autoantibodies are normal in a well-balanced immune system, and serve various roles to help the body dispose of wastes, protect from invaders that have similarity to human structures, and to keep blood vessels clear. In healthy people, autoantibodies tend to be well-regulated and well "masked," or covered up, until needed. Therefore, it is probably the high activity and high detectability of autoantibodies that makes lupus unique, not the fact that they exist.

Many people who have viral syndromes or have reached the age of 50 test positive for the anti-nuclear autoantibody (ANA). Thus, this common screening test for lupus is actually an autoantibody which is found in many healthy people, and a positive ANA would never give someone a diagnosis of lupus in the absence of lupus symptoms or other disease features.

The Inflammatory Process and Autoimmunity

The Normal Immune System Response. The inflammatory process is a byproduct of the activity of the body's immune system, which fights infection and heals wounds and injuries:

When an injury or an infection occurs, white blood cells are mobilized to rid the body of any foreign proteins, such as a virus.
The masses of blood cells that gather at the injured or infected site produce factors to fight any infections.
In the process, the surrounding area becomes inflamed and some healthy tissue is injured. The immune system is then called upon to repair wounds by clotting any bleeding blood vessels and initiating fiber-like patches to the tissue.
Under normal conditions, the immune system has special factors that control and limit this inflammatory process.