What is Lupus?
Lupus is a chronic inflammatory disease that can affect various systems of the body, especially the skin, joints, blood, and kidneys. The body’s immune system normally makes proteins called antibodies to protect the body against viruses, bacteria, and other foreign materials. These foreign materials are called antigens. In an autoimmune disorder such as lupus, the immune system loses its ability to tell the difference between foreign substances (antigens) and its own cells and tissues. The immune system then makes antibodies directed against “self.” These antibodies, called “auto-antibodies,” react with the “self” antigens to form immune complexes. The immune complexes build up in the tissues and can cause inflammation, injury to tissues, and pain.
For most people, lupus is a mild disease affecting only a few organs. For others, it may cause serious and even life-threatening problems. More than 16,000 Americans develop lupus each year. It is estimated that 500,000 to 1.5 million Americans have been diagnosed with lupus.
Types of Lupus
There are three types of lupus: discoid, systemic, and drug-induced. Discoid (cutaneous) lupus is usually, but not always limited to the skin. It is identified by a rash that may appear on the face, neck, and scalp. Discoid lupus is diagnosed by examining a biopsy of the rash. In discoid lupus the biopsy will show abnormalities that are not found in skin without the rash. Discoid lupus does not generally involve the body’s internal organs. Therefore, the ANA test, a blood test used to detect systemic lupus, may be negative in patients with discoid lupus. However, in a large number of patients with discoid lupus, the ANA test is positive, but at a low level or strength. We call this level a titer.
In approximately 10 percent of patients, discoid lupus can evolve into the systemic form of the disease, which can affect almost any organ or system of the body. This cannot be predicted or prevented. Treatment of discoid lupus will not prevent its progression to the systemic form. Individuals who progress to the systemic form probably had systemic lupus at the outset, with the discoid rash as a major symptom.
Systemic lupus is usually more severe than discoid lupus and can affect almost any organ or system of the body. For some people, only the skin and joints will be involved. In others, the joints, lungs, kidneys, blood, or other organs and/or tissues may be affected. Generally, no two people with systemic lupus will have identical symptoms. Systemic lupus may include periods in which few, if any, symptoms are evident (“remission”) and other times when the disease becomes more active (“flare”). Most often when people mention “lupus,” they are referring to the systemic form of the disease.
Drug-induced lupus occurs after the use of certain prescribed drugs. The symptoms of drug-induced lupus are similar to those of systemic lupus. The drugs most commonly connected with drug-induced lupus are hydralazine (used to treat high blood pressure or hypertension), procainamide (used to treat irregular heart rhythms), and Isoniazid (a drug used to treat TB). Drug induced lupus is more common in men, because they are given these drugs more often, however this may not be the case now because of a resurgence of tuberculosis and the drugs used to treat that disease.. Not everyone who takes these drugs will develop drug-induced lupus and only about 4 percent of the people who take these drugs will develop the antibodies suggestive of lupus. Of those 4 percent, only an extremely small number will develop the disease which we call drug-induced lupus. The symptoms usually leave when the medications are discontinued.
Although drug-induced lupus and discoid lupus share features of systemic lupus, the rest of this brochure primarily discusses systemic lupus.
The cause(s) of lupus is unknown, but there are environmental and genetic factors involved. While scientists believe there is a genetic predisposition to the disease, it is known that environmental factors also play a critical role in triggering lupus. Some of the environmental factors that may trigger the disease are: infections, antibiotics (especially those in the sulfa and penicillin groups), ultraviolet light, extreme stress, certain drugs, and hormones.
Although lupus is known to occur within families, there is no known gene or genes which are thought to cause the illness. There are recent discoveries of genes on chromosomes like number 1 which is associated with lupus in certain families. Previously, genes on chromosome 6 called “immune response genes” were associated with the disease and studied intensely. We now know that lupus can involve major genes on many chromosomes and this is an active area of research. Only 10 percent of lupus patients will have a close relative (parent or sibling) who already has or may develop lupus. Statistics show that only about 5% of the children born to individuals with lupus will develop the illness. Lupus can occur in identical twins, but the chance of the disease occurring in both twins is about 30%, supporting the idea that origins of the disease are genetic in part, while other factors play a role.
Lupus is often called a “woman’s disease” despite the fact that many men are affected. While lupus can occur at any age in either sex, it occurs 10-15 times more frequently among adult females than adult males after puberty; after emergence into sexual maturity. The symptoms of the disease are the same in men and women. Women of African, Hispanic, American Indian, and Asian origin are thought to develop the disease more frequently than Caucasian women. The reasons for this ethnic selection are not clear, but it is important because the death rate for lupus in African American women is higher than that of other races. The reason for this is unknown.