Lupus

Systemic Lupus Erythematosus

U.S Department of Health and Human Services
National Institutes of Health

National Institute of Arthritis and Musculoskeletal and Skin Diseases

Defining Lupus

Lupus is one of many disorders of the immune system known as autoimmune diseases. In autoimmune diseases, the immune system turns against parts of the body it is designed to protect. This leads to inflammation and damage to various body tissues. Lupus can affect many parts of the body, including the joints, skin, kidneys, heart, lungs, blood vessels, and brain. Although people with the disease may have many different symptoms, some of the most common ones include extreme fatigue, painful or swollen joints (arthritis), unexplained fever, skin rashes, and kidney problems.

At present, there is no cure for lupus. However, lupus can be effectively treated with drugs, and most people with the disease can lead active, healthy lives. Lupus is characterized by periods of illness, called flares, and periods of wellness, or remission. Understanding how to prevent flares and how to treat them when they do occur helps people with lupus maintain better health. Intense research is underway, and scientists funded by the NIH are continuing to make great strides in understanding the disease, which may ultimately lead to a cure.

Two of the major questions researchers are studying are who gets lupus and why. We know that many more women than men have lupus. Lupus is three times more common in African American women than in Caucasian women and is also more common in women of Hispanic, Asian, and Native American descent. In addition, lupus can run in families, but the risk that a child or a brother or sister of a patient will also have lupus is still quite low. It is difficult to estimate how many people in the United States have the disease because its symptoms vary widely and its onset is often hard to pinpoint.

There are several kinds of lupus:

• Systemic lupus erythematosus (SLE) is the form of the disease that most people are referring to when they say "lupus." The word "systemic" means the disease can affect many parts of the body. The symptoms of SLE may be mild or serious. Although SLE usually first affects people between the ages of 15 and 45 years, it can occur in childhood or later in life as well. This booklet focuses on SLE.

• Discoid lupus erythematosus is a chronic skin disorder in which a red, raised rash appears on the face, scalp, or elsewhere. The raised areas may become thick and scaly and may cause scarring. The rash may last for days or years and may recur. A small percentage of people with discoid lupus have or develop SLE later.

• Subacute cutaneous lupus erythematosus refers to skin lesions that appear on parts of the body exposed to sun. The lesions do not cause scarring.

• Drug-induced lupus is a form of lupus caused by medications. Many different drugs can cause drug-induced lupus. Symptoms are similar to those of SLE (arthritis, rash, fever, and chest pain) and they typically go away completely when the drug is stopped. The kidneys and brain are rarely involved.

• Neonatal lupus is a rare disease that can occur in newborn babies of women with SLE, Sjögren's syndrome, or no disease at all. Scientists suspect that neonatal lupus is caused by autoantibodies in the mother's blood called anti-Ro (SSA) and anti-La (SSB). Autoantibodies ("auto" means self) are blood proteins that act against the body's own parts. At birth, the babies have a skin rash, liver problems, and low blood counts. These symptoms gradually go away over several months. In rare instances, babies with neonatal lupus may have a serious heart problem that slows down the natural rhythm of the heart. Neonatal lupus is rare, and most infants of mothers with SLE are entirely healthy. All women who are pregnant and known to have anti-Ro (SSA) or anti-La (SSB) antibodies should be monitored by echocardiograms (a test that monitors the heart and surrounding blood vessels) during the 16th and 30th weeks of pregnancy.
  
  It is important for women with SLE or other related autoimmune disorders to be under a doctor's care during pregnancy. Physicians can now identify mothers at highest risk for complications, allowing for prompt treatment of the infant at or before birth. SLE can also flare during pregnancy, and prompt treatment can keep the mother healthier longer.

Understanding What Causes Lupus

Lupus is a complex disease, and its cause is unknown. It is likely that a combination of genetic, environmental, and possibly hormonal factors work together to cause the disease. Scientists are making progress in understanding lupus, as described here and in the "Current Research" section of this booklet. The fact that lupus can run in families indicates that its development has a genetic basis. Recent research suggests that genetics plays an important role; however, no specific "lupus gene" has been identified yet. Studies suggest that several different genes may be involved in determining a person's likelihood of developing the disease, which tissues and organs are affected, and the severity of disease. However, scientists believe that genes alone do not determine who gets lupus and that other factors also play a role. Some of the factors scientists are studying include sunlight, stress, certain drugs, and infectious agents such as viruses.

In lupus, the body's immune system does not work as it should. A healthy immune system produces proteins called antibodies and specific cells called lymphocytes that help fight and destroy viruses, bacteria, and other foreign substances that invade the body. In lupus, the immune system produces antibodies against the body's healthy cells and tissues. These antibodies, called autoantibodies, contribute to the inflammation of various parts of the body and can cause damage to organs and tissues. The most common type of autoantibody that develops in people with lupus is called an antinuclear antibody (ANA) because it reacts with parts of the cell's nucleus (command center). Doctors and scientists do not yet understand all of the factors that cause inflammation and tissue damage in lupus, and researchers are actively exploring them.