Autoimmune Disorders Health Article

Autoimmune Disorders

Diseases in which the immune system attacks the body's own healthy tissues, forming antibodies in an assault on mistakenly identified "foreign invaders. "

Autoimmune disorders occur when the body's immune system loses its ability to recognize the differences between self and nonself tissues. The body then builds antibodies to attack its own tissues and organs, which culminates in a number of different disorders. Some of these become chronic illnesses and may lead to death.

Two of the earliest illnesses identified as autoimmune disorders were systematic lupus erythematosus (SLE) and rheumatoid arthritis. Today more than 40 conditions are classified as known or probable autoimmune disorders. It is estimated that autoimmune diseases affect between 5-7% of the population. Most begin during or soon after puberty, or when a person reaches his or her forties and fifties. They occur twice as frequently in women as in men.

Rheumatoid arthritis occurs in both children and adults, and is the most common autoimmune disorder. Juvenile rheumatoid arthritis (JRA) affects over 65,000 children and adolescents in the United States, or about 1 in 1,000. In this disorder, the immune system attacks the synovium, a membrane surrounding the joints, resulting in pain, swelling, and stiffness. Like other autoimmune disorders, rheumatoid arthritis is usually episodic, flaring up periodically, subsiding, and then recurring.

There are three distinct types of JRA, differentiated by their severity and by how much of the body is affected. Pauciarticular onset JRA involves fewer than five joints; polyarticular onset JRA affects five or more joints on both sides of the body; and systemic onset JRA affects a large number of joints and other organs as well, such as the lungs, kidneys, liver, spleen, and lymph nodes. Juvenile rheumatoid arthritis is treated with a combination of drugs and physical therapy. The medications of choice are NSAIDS (nonsteroidal anti-inflammatory drugs), especially aspirin in large doses. Physical therapy includes a variety of exercises designed to keep the muscles near the affected joints strong and flexible, prevent them from getting shorter, and prevent bone deformity. JRA goes into permanent remission by late adolescence or early adulthood in approximately 75% of children affected by the disease.

Another serious autoimmune disorder that affects children is Type 1 diabetes mellitus, also known as juvenile onset diabetes because symptoms generally appear in early adolescence. Type 2 diabetes mellitus, the most prevalent form of the disease, usually begins in middle age. Diabetes occurs when the pancreas does not produce enough of the hormone insulin, which the body requires to metabolize the blood sugar glucose, a crucial energy source. The condition was first identified as an autoimmune disorder in 1988, when researchers discovered that it is caused by antibodies that attack the insulin-producing cells in the pancreas. Its onset is now thought to be linked to a genetic predisposition combined with a virus or another Stressor. In Type 1 diabetes mellitus, the depletion of insulin is so severe that injections of the hormone are necessary. Symptoms of juvenile onset diabetes include extreme thirst, frequent urination, increased appetite together with sudden weight loss, irritability, fatigue, and nausea. In addition to daily insulin injections (which must be continued for life), treatment of diabetes mellitus requires monitoring of the level of glucose in the blood, which must also be regulated by adequate exercise and certain dietary measures. Too much glucose can damage the eyes, kidneys, and other organs, and it also presents the risk of a diabetic coma. Too little can produce insulin shock.

Rheumatic fever, which primarily affects children between the ages of four and 18, is an autoimmune disorder that occurs following a strep infection, such as strep throat or scarlet fever. The antibodies produced to fight the infection attack healthy tissues in the heart, joints, skin, and nervous system. Due to the widespread use of antibiotics to combat strep infections, rheumatic fever is rare in developed countries. Symptoms include fever, joint pain and swelling, muscle aches, a rash (possibly intermittent) on the trunk and extremities, nodules in the joints, scalp, or spine, and twitching arms or legs. If the central nervous system is affected, there can also be emotional volatility, muscle weakness, and coordination problems; however, these symptoms are short-lived and temporary, and do not cause lasting damage. Rheumatic fever generally takes between one and four weeks to develop following a strep infection and lasts from two weeks to three months. If the tissues of the heart are inflamed, a condition known as carditis, this can cause permanent damage to the heart valves. Once rheumatic fever is diagnosed, antibiotics are administered if there is still an active strep infection. In addition to anti-inflammatory medications such as aspirin, a child whose heart is affected by the disease may be given steroids to reduce inflammation and prevent permanent heart damage.

An autoimmune disorder that primarily affects adults but is also found in children is systematic lupus erythematosus, also known as SLE or lupus. A victim of lupus develops antibodies that attack connective tissues throughout the body. The heart, lungs, and kidneys can be affected, as well as the blood, joints, and central nervous system. Of the estimated 500,000 Americans affected by this disease, some 15% are children, whose symptoms are generally more severe than those of adults. The incidence of lupus in females is nine times that in males.

The most distinctive sign of lupus is a butterflyshaped rash across the cheeks and the bridge of the nose. However, this only occurs in about a third of those affected by the disease, which can produce a wide variety of symptoms shared by other conditions. This makes diagnosis so difficult that many affected persons suffer from lupus for three to 10 years before being diagnosed. Other symptoms include fever, fatigue, weight loss, anemia, swelling and pain in the joints, and sensitivity to cold and light. Once it appears, lupus is never wholly cured; it may go into remission for extended periods of time and then flare up again suddenly. Lupus has traditionally been treated with anti-inflammatory medications, including aspirin and corticosteroids. Currently, most physicians control the disease with small doses of steroids to prevent side effects and use aspirin and other NSAIDS (non-steroidal anti-inflammatory drugs) to relieve pain. In very acute attacks, drugs such as cyclophosphamide that temporarily suppress the immune system may be used.

Another autoimmune disorder that can affect children is psoriasis, often appearing in adolescence or young adulthood, although about 10% of cases occur in children under the age of 10, and it can even appear in infancy. Psoriasis is caused by the excessive growth of certain skin cells called keratinocytes. Its primary symptom is the appearance of red, raised patches of skin called plaques, usually found on the scalp, elbows, knees, arms, legs, back, and genitalia, but can occur anywhere, and may cover up to 80% of the body. When psoriasis begins in infancy, it most frequently appears in the diaper area. In many cases the plaques cause severe itching and soreness, but they may also be painless. The fingernails of up to one half of children with psoriasis are also affected, becoming pitted or showing other changes. In addition to physical discomfort, psoriasis can cause great emotional distress due to its effect on the patient's appearance.

Psoriasis is chronic and incurable. Its symptoms may be alleviated by creams or lotions that help moisturize the skin or that contain cortisone to reduce inflammation. Tar-based creams are also used in some cases. Exposure to ultraviolet light, including sunlight, can also alleviate the symptoms of psoriasis. Immuno-suppressant medications, such as cyclosporine and methotrexate, may be used for very serious flare-ups, but their use is discouraged because of potential side effects.

Of the various types of anemia that can affect children, at least one is an autoimmune disorder. In rare autoimmune hemolytic anemia, red blood cells are attacked by the immune system, which kills the old cells faster than the body can manufacture new ones. Classic symptoms of anemia, including pallor, fatigue, and weakness, appear. Secretion of the destroyed red blood cells can turn the urine red. The condition may appear slowly over a period of days, or the onset may be rapid and lifethreatening, with sudden extreme fatigue and jaundice. A blood transfusion, the normal emergency treatment for a low blood count, may be impossible for a person with autoimmune hemolytic anemia because the immune system may also attack the red cells of the transfused blood. In most cases, the blood count returns to normal within a relatively short period of time. However, in persons whose blood count drops precipitously and whose bodies reject transfusions, this form of anemia may cause shock, heart failure, and death.

Researchers are not certain what triggers autoimmune disorders. It is thought that certain viruses and bacteria may have evolved to resemble the body's own tissues in an attempt to evade detection by the immune system. When these viruses or bacteria are present, the body's immune system may become confused and attack both the foreign substances and its own tissues. (This would explain why rheumatic fever appears in conjunction with strep infections.) Genetic susceptibility is known to play a role in certain autoimmune disorders, as does stress. Stress, though, is thought to bring on relapses of a disease, rather than cause its onset.

As more and more autoimmune disorders are identified, interest has grown in finding ways to prevent or cure them. Increasing attention has been focused on finding ways to isolate and stop harmful antibody activity without suppressing the entire immune system, which makes the body vulnerable to infections and causes dangerous side effects. Cyclosporine, which became available in 1984 and targets only specialized immune cells, called T-cells, increases production of a specific antibody. Cyclosporine has been successfully used to treat a variety of autoimmune disorders, especially psoriasis. It is thought that this type of selective targeting may eventually provide the basis for vaccines that can protect the body by preventing T-cells from manufacturing harmful antibodies.

Another promising research area is a type of treatment known as oral tolerization, based on research showing that tolerance to a particular substance can be increased by administering it orally, and the increased tolerance can prevent or halt an autoimmune reaction. Conditions with known antigens (materials that provoke an autoimmune reaction, such as insulin in diabetics or myelin in persons with multiple sclerosis) have responded well to treatments that include oral ingestion of the very substances that are under attack by their own bodies.

Known autoimmune disorders, other than those affecting children, include multiple sclerosis, Graves' disease (a thyroid condition), and Addison's disease (a disorder of the adrenal gland). Disorders in which autoimmune response is suspected include Alzheimer's disease, atherosclerosis, irritable bowel syndrome, and uveitis (an eye inflammation).

See also Arthritis; Diabetes Mellitus