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Autoimmune Disorders

Autoimmune Disorders

Definition

Autoimmune disorders are conditions in which a person's immune system attacks the body's own cells, causing tissue destruction.

Description

Autoimmunity is accepted as the cause of a wide range of disorders, and it is suspected to be responsible for many more. Autoimmune diseases are classified as either general, in which the autoimmune reaction takes place simultaneously in a number of tissues, or organ specific, in which the autoimmune reaction targets a single organ.

Autoimmune disorders include the following:

  • Systemic lupus erythematosus. A general autoimmune disease in which antibodies attack a number of different tissues. The disease recurs periodically and is seen mainly in young and middle-aged women.
  • Rheumatoid arthritis. Occurs when the immune system attacks and destroys the tissues that line bone joints and cartilage. The disease occurs throughout the body, although some joints may be more affected than others.
  • Goodpasture's syndrome. Occurs when antibodies are deposited in the membranes of both the lung and kidneys, causing both inflammation of kidney glomerulus (glomerulonephritis ) and lung bleeding. It is typically a disease of young males.
  • Grave's disease. Caused by an antibody that binds to specific cells in the thyroid gland, causing them to make excessive amounts of thyroid hormone.
  • Hashimoto's thyroiditis. Caused by an antibody that binds to cells in the thyroid gland. Unlike in Grave's disease, however, this antibody's action results in less thyroid hormone being made.
  • Pemphigus vulgaris. A group of autoimmune disorders that affect the skin.
  • Myasthenia gravis. A condition in which the immune system attacks a receptor on the surface of muscle cells, preventing the muscle from receiving nerve impulses and resulting in severe muscle weakness.
  • Scleroderma. Also called CREST syndrome or progressive systemic sclerosis, scleroderma affects the connective tissue.
  • Autoimmune hemolytic anemia. Occurs when the body produces antibodies that coat red blood cells.
  • Autoimmune thrombocytopenic purpura. Disorder in which the immune system targets and destroys blood platelets.
  • Polymyositis and Dermatomyositis. Immune disorders that affect the neuromuscular system.
  • Pernicious anemia. Disorder in which the immune system attacks the lining of the stomach in such a way that the body cannot metabolize vitamin B12.
  • Sjögren's syndrome. Occurs when the exocrine glands are attacked by the immune system, resulting in excessive dryness.
  • Ankylosing spondylitis. Immune system induced degeneration of the joints and soft tissue of the spine.
  • Vasculitis. A group of autoimmune disorders in which the immune system attacks and destroys blood vessels.
  • Type I diabetes mellitus. May be caused by an antibody that attacks and destroys the islet cells of the pancreas, which produce insulin.
  • Amyotrophic lateral schlerosis. Also called Lou Gehrig's disease. An immune disorder that causes the death of neurons which leads to progressive loss of muscular control.
  • Guillain-Barre syndrome. Also called infectious polyneuritis. Often occurring after an infection or an immunization (specifically Swine flu), the disease affects the myelin sheath, which coats nerve cells. It causes progressive muscle weakness and paralysis.
  • Multiple sclerosis. An autoimmune disorder that may involve a virus affects the central nervous system, causing loss of coordination and muscle control.

Causes and symptoms

To further understand autoimmune disorders, it is helpful to understand the workings of the immune system. The purpose of the immune system is to defend the body against attack by infectious microbes (germs) and foreign objects. When the immune system attacks an invader, it is very specifica particular immune system cell will only recognize and target one type of invader. To function properly, the immune system must not only develop this specialized knowledge of individual invaders, but it must also learn how to recognize and not destroy cells that belong to the body itself. Every cell carries protein markers on its surface that identifies it in one of two ways: what kind of cell it is (e.g. nerve cell, muscle cell, blood cell, etc.) and to whom that cell belongs. These markers are called major histocompatability complexes (MHCs). When functioning properly, cells of the immune system will not attack any other cell with markers identifying it as belonging to the body. Conversely, if the immune system cells do not recognize the cell as "self," they attach themselves to it and put out a signal that the body has been invaded, which in turn stimulates the production of substances such as antibodies that engulf and destroy the foreign particles. In case of autoimmune disorders, the immune system cannot distinguish between "self" cells and invader cells. As a result, the same destructive operation is carried out on the body's own cells that would normally be carried out on bacteria, viruses, and other such harmful entities.

The reasons why immune systems become dysfunctional in this way is not well understood. However, most researchers agree that a combination of genetic, environmental, and hormonal factors play into autoimmunity. Researchers also speculate that certain mechanisms may trigger autoimmunity. First, a substance that is normally restricted to one part of the body, and therefore not usually exposed to the immune system, is released into other areas where it is attacked. Second, the immune system may mistake a component of the body for a similar foreign component. Third, cells of the body may be altered in some way, either by drugs, infection, or some other environmental factor, so that they are no longer recognizable as "self" to the immune system. Fourth, the immune system itself may be damaged, such as by a genetic mutation, and therefore cannot function properly.

KEY TERMS

Autoantibody An antibody made by a person that reacts with their own tissues.

Paresthesias A prickly, tingling sensation.

The symptoms of the above disorders include:

  • Systemic lupus erythematosus. Symptoms include fever, chills, fatigue, weight loss, skin rashes (particularly the classic "butterfly" rash on the face), vasculitis, polyarthralgia, patchy hair loss, sores in the mouth or nose, lymph-node enlargement, gastric problems, and, in women, irregular periods. About half of those who suffer from lupus develop cardiopulmonary problems, and some may also develop urinary problems. Lupus can also effect the central nervous system, causing seizures, depression, and psychosis.
  • Rheumatoid arthritis. Initially may be characterized by a low-grade fever, loss of appetite, weight loss, and a generalized pain in the joints. The joint pain then becomes more specific, usually beginning in the fingers, then spreading to other areas, such as the wrists, elbows, knees, and ankles. As the disease progresses, joint function diminishes sharply and deformities occur, particularly the characteristic "swan's neck" curling of the fingers.
  • Goodpasture's syndrome. Symptoms are similar to that of iron deficiency anemia, including fatigue and pallor. Symptoms involving the lungs may range from a cough that produces bloody sputum to outright hemorrhaging. Symptoms involving the urinary system include blood in the urine and/or swelling.
  • Grave's disease. This disease is characterized by an enlarged thyroid gland, weight loss without loss of appetite, sweating, heart palpitations, nervousness, and an inability to tolerate heat.
  • Hashimoto's thyroiditis. This disorder generally displays no symptoms.
  • Pemphigus vulgaris. This disease is characterized by blisters and deep lesions on the skin.
  • Myasthenia gravis. Characterized by fatigue and muscle weakness that at first may be confined to certain muscle groups, but then may progress to the point of paralysis. Myasthenia gravis patients often have expressionless faces as well as difficulty chewing and swallowing. If the disease progresses to the respiratory system, artificial respiration may be required.
  • Scleroderma. Disorder is usually preceded by Raynaud's phenomenon. Symptoms that follow include pain, swelling, and stiffness of the joints, and the skin takes on a tight, shiny appearance. The digestive system also becomes involved, resulting in weight loss, appetite loss, diarrhea, constipation, and distention of the abdomen. As the disease progresses, the heart, lungs, and kidneys become involved, and malignant hypertension causes death in approximately 30% of cases.
  • Autoimmune hemolytic anemia. May be acute or chronic. Symptoms include fatigue and abdominal tenderness due to an enlarged spleen.
  • Autoimmune thrombocytopenic purpura. Characterized by pinhead-size red dots on the skin, unexplained bruises, bleeding from the nose and gums, and blood in the stool.
  • Polymyositis and Dermatomyositis. In polymyositis, symptoms include muscle weakness, particularly in the shoulders or pelvis, that prevents the patient from performing everyday activities. In dermatomyositis, the same muscle weakness is accompanied by a rash that appears on the upper body, arms, and fingertips. A rash may also appear on the eyelids, and the area around the eyes may become swollen.
  • Pernicious anemia. Signs of pernicious anemia include weakness, sore tongue, bleeding gums, and tingling in the extremities. Because the disease causes a decrease in stomach acid, nausea, vomiting, loss of appetite, weight loss, diarrhea, and constipation are possible. Also, because Vitamin B12 is essential for the nervous system function, the deficiency of it brought on by the disease can result in a host of neurological problems, including weakness, lack of coordination, blurred vision, loss of fine motor skills, loss of the sense of taste, ringing in the ears, and loss of bladder control.
  • Sjögren's syndrome. Characterized by excessive dryness of the mouth and eyes.
  • Ankylosing spondylitis. Generally begins with lower back pain that progresses up the spine. The pain may eventually become crippling.
  • Vasculitis. Symptoms depend upon the group of veins affected and can range greatly.
  • Type I diabetes mellitus. Characterized by fatigue and an abnormally high level of glucose in the blood (hyperglycemia).
  • Amyotrophic lateral schlerosis. First signs are stumbling and difficulty climbing stairs. Later, muscle cramps and twitching may be observed as well as weakness in the hands making fastening buttons or turning a key difficult. Speech may become slowed or slurred. There may also be difficluty swallowing. As respiratory muscles atrophy, there is increased danger of aspiration or lung infection.
  • Guillain-Barre syndrome. Muscle weakness in the legs occurs first, then the arms and face. Paresthesias (a prickly, tingling sensation) is also felt. This disorder affects both sides of the body and may involve paralysis and the muscles that control breathing.
  • Multiple sclerosis. Like Lou Gehrig's disease, the first symptom may be clumsiness. Weakness or exhaustion is often reported, as well as blurry or double vision. There may be dizziness, depression, loss of bladder control, and muscle weakness so severe that the patient is confined to a wheelchair.

Diagnosis

A number of tests are involved in the diagnosis of autoimmune diseases, depending on the particular disease; e.g. blood tests, cerebrospinal fluid analysis, electromylogram (measures muscle function), and magnetic resonance imaging of the brain. Usually, these tests determine the location and extent of damage or involvement. They are useful in charting progress of the disease and as baselines for treatment.

The principle tool, however, for authenticating autoimmune disease is antibody testing. Such tests involve measuring the level of antibodies found in the blood and determining if they react with specific antigens that would give rise to an autoimmune reaction. An elevated amount of antibodies indicates that a humoral immune reaction is occurring. Since elevated antibody levels are also seen in common infections, they must be ruled out as the cause for the increased antibody levels.

Antibodies can also be typed by class. There are five classes of antibodies, and they can be separated in the laboratory. The class IgG is usually associated with autoimmune diseases. Unfortunately, IgG class antibodies are also the main class of antibody seen in normal immune responses.

The most useful antibody tests involve introducing the patient's antibodies to samples of his or her own tissue, usually thyroid, stomach, liver, and kidney tissue. If antibodies bind to the "self" tissue, it is diagnostic for an autoimmune disorder. Antibodies from a person without an autoimmune disorder would not react to "self " tissue.

Treatment

Treatment of autoimmune diseases is specific to the disease, and usually concentrates on alleviating or preventing symptoms rather than correcting the underlying cause. For example, if a gland involved in an autoimmune reaction is not producing a hormone such as insulin, administration of that hormone is required. Administration of a hormone, however, will restore the function of the gland damaged by the autoimmune disease.

The other aspect of treatment is controlling the inflammatory and proliferative nature of the immune response. This is generally accomplished with two types of drugs. Steroid compounds are used to control inflammation. There are many different steroids, each having side effects. The proliferative nature of the immune response is controlled with immunosuppressive drugs. These drugs work by inhibiting the replication of cells and, therefore, also suppress non-immune cells leading to side effects such as anemia.

Systemic enzyme therapy is a new treatment that is showing results for rheumatoid arthritis, multiple sclerosis, ankylosing spondylitis, and other inflammatory diseases. Enzymes combinations of pancreatin, trypsin, chymotrypsin, bromelain, and papain help stimulate the body's own defenses, accelerate inflammation in order to reduce swelling and improve circulation, and break up the immune complexes within the bloodstream. Symptoms have been reduced using this treatment.

Other treatments that hold some promise are irradiation of the spleen and gene therapy. Splenic irradiation is touted to be a safe, alternative for patients with autoimmune blood diseases, especially autoimmune hemolytic anemia, or others with compromised immune systems, such as HIV patients and the elderly. It is reported to have few side effects and seems to be working. Cytokine and cytokine inhibitor genes injected directly into muscle tissue also appear to be effective in treating Type I diabetes mellitus, systemic lupus erythematosus, thyroditis, and arthritis.

Prognosis

Prognosis depends upon the pathology of each autoimmune disease.

Prevention

Most autoimmune diseases cannot be prevented. Though the mechanisms involved in how these diseases affect the body are known, it is still unclear why the body turns on itself. Since more women than men seem to be affected by some of these disorders (e.g. lupus), some researchers are looking into hormones as a factor. This, and gene therapy, may be the preventatives of the future.

Resources

PERIODICALS

Cichoke, Anthony J. "Natural Relief for Autoimmune Disorders." Better Nutrition. 62, no. 6 (June 2000): 24.

Henderson, Charles W. "Gene Therapy Uses Vectors EncodingCytokines or Cytokine Inhibitors (for treatment of autoimmune disorders)." ImmunotherapyWeekly September 27, 2000: pNA.

Riccio, Nina M. "Autoimmune Disorder: When the Body AttacksItself." Current Health 2 26, no. 5 (January 2000): 13.

"Splenic Irradiation Is an Option for Patients with AutoimmuneDisorders and Those with HIV." AIDS Weekly (April 9, 2001): pNA.

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Franz, Janie. "Autoimmune Disorders." Gale Encyclopedia of Medicine, 3rd ed.. 2006. Encyclopedia.com. 26 Jun. 2016 <http://www.encyclopedia.com>.

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Franz, Janie. "Autoimmune Disorders." Gale Encyclopedia of Medicine, 3rd ed.. 2006. Retrieved June 26, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3451600206.html

autoimmune disease

autoimmune disease Every second of our lifetime, we are exposed to a large variety of microorganisms in the environment, which are capable of causing fatal diseases. However, normal individuals rarely succumb to such infections and, even if they do, it is usually for a short duration and with limited damage. This is because of an efficient immune system that destroys these organisms and other foreign substances.

An immune response is brought about by two components of the immune system, namely the innate immunity and the acquired or specific immunity, acting in conjunction with each other and with other molecules. Acquired immunity involves the production of antibodies, each specifically designed to combat a particular antigen — a component of the invading substance or organism. For its normal function of defence, five features of the acquired immune system are essential. These are: (i) specificity for distinct antigens; (ii) diversity; (iii) memory; (iv) self-limitation; and (v) discrimination of self from non-self.

It is the last two features which raise the possibility of Dr Jekyll turning into Mr Hyde. Loss of self-limitation or the failure to maintain self-tolerance can actually turn the immune system from playing a defensive role to causing debilitating diseases. A pathological condition arising from uncontrolled or aberrant immune responses is defined as a hypersensitivity reaction, or allergy. Diseases that are caused due to the immune system acting against self-antigens are called ‘autoimmune diseases’, a situation which has been melodramatically described as ‘horror autotoxicus’ by the famous biologist Paul Erlich.

A wide range of diseases have now been classified as having autoimmune causes. At one end of the spectrum of such diseases are conditions like Hashimoto's thyroiditis, where the antibodies are directed against one specific organ (in this case the thyroid gland). At the other end of the spectrum are diseases such as systemic lupus erythematosus (SLE), where the antibodies are directed against the nucleus of the cells, thereby affecting the whole body; in most instances, specific antibodies can be detected circulating in the blood. In another disease condition, known as Goodpasture's syndrome, the autoantibodies bind to components of the membrane that separates air from blood in the alveoli of the lungs and of the glomerular capillaries of kidneys, where filtration occurs. This causes a localized immune reaction and leads to lung haemorrhages and glomerulonephritis. Similarly, in autoimmune haemolytic anaemia antibodies are directed against red blood cells, enhancing breakdown and phagocytosis of the cells.

In certain cases, however, the autoantibodies do not cause cell damage, but instead alter the normal physiological functions by mimicking normal signalling molecules. For example, in Grave's disease (thyrotoxicosis) autoantibodies bind to the receptors for the thyroid stimulating hormone (TSH) from the pituitary gland and mimic its functions, leading to excessive thyroid hormone production. In another disease, known as myasthenia gravis, autoantibodies bind to the receptors on muscle cells for the neurotransmitter, acetylcholine, and thereby inhibit nerve-to-muscle conduction; over a period of time these receptors are endocytosed (taken up inside the cells) and degraded, causing progressive muscle paralysis.

Sometimes, autoimmune diseases may arise because antibodies, which are produced against foreign antigens, cross-react with the body's own proteins (‘self-proteins’). Thus in acute rheumatic fever, which can develop following a throat infection, antibodies against a cell wall protein of streptococcus bacteria may cross-react with an antigen in the person's own cardiac muscle cells. This leads to myocarditis and damage to the valves of the heart. It is also associated with inflammation of the joints and destruction of the joint cartilage brought about by immune responses.

The immune response involves not only the production of antibodies which circulate in the blood, but also the multiple activities of ‘T-cells’, the lymphocytes which have been ‘programmed’ in the thymus gland to recognize specific antigens, and which mediate the ‘cellular’ component of the immune response. In certain autoimmune diseases, it is the T-cells which become auto-reactive. This occurs in some patients with insulin-dependent diabetes mellitus. In these patients, activated lymphocytes and macrophages destroy the insulin-producing cells in the pancreas, which leads to the disorders of metabolism characteristic of this condition. Some types of anaemia are thought to be due to antibodies being generated against factors required for absorption from the gut of vitamin B12, which is essential for maturation of red blood cells.

Besides the examples described, numerous other pathological conditions have also been classified as autoimmune diseases. Extensive research has been conducted to elucidate the mechanisms by which the immune system discriminates between self and non-self, and the transformation from protector to aggressor in certain pathological conditions of autoimmunity.

One of the cardinal features of immunity is the ability to maintain self-tolerance against self-antigens. Its is an actively acquired process, where self-reactive antibodies are prevented from becoming functionally capable of reacting with self-antigens. A negative selection process plays a major role, whereby immature T-cells, specific for self-antigens, are deleted in the thymus. In certain conditions, the clones may survive but are unable to respond to self-antigens. This is known as clonal ignorance. All these mechanisms lead to the capability of the immune system to discriminate between self and non-self.

Despite these several mechanisms for inducing self-tolerance, autoimmunity remains a significant cause of disease in humans. Multiple factors are implicated in the breakdown of self-tolerance. These factors range from genetic predisposition to microbial infections. Autoimmunity can also arise from abnormalities in lymphocytes following failure of the selection process in the thymus. It is proposed that an individual's ‘major histocompatibility’ genes, which determine their ‘HLA type’ (classification based on human lymphocyte antigens, used in determining tissue compatibility for organ transplants), influence thymic selection, implying a genetic role in autoimmunity. Studies of a particular strain of mice, which develops an accelerated, severe form of systemic autoimmunity, revealed a genetic predisposition. Indeed, autoimmune diseases are often said to ‘run in the family’. HLA typing has shown that some individuals have 90 to 100 times the average predisposition to developing the autoimmune condition called ankylosing spondylosis. This may possibly be due to the controlling of T-cell selection and activation by the gene products which determine the HLA type.

Some autoimmune diseases are caused when antibodies or T-cells, stimulated to act against a foreign antigen, recognize a similar molecular component on a self-protein. This ‘molecular mimicry’ is often a cause for autoimmunity, as described earlier in the case of rheumatic fever.

A plethora of causal factors are thus implicated in leading to autoimmunity. Recent advances have also been made in elucidating the mechanisms involved in self-tolerance and generation of autoimmunity; these hold promise for development of effective strategies for management of these debilitating conditions.

Shiladitya Sengupta, and Tai-Ping Fan


See also immune system.

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COLIN BLAKEMORE and SHELIA JENNETT. "autoimmune disease." The Oxford Companion to the Body. 2001. Encyclopedia.com. 26 Jun. 2016 <http://www.encyclopedia.com>.

COLIN BLAKEMORE and SHELIA JENNETT. "autoimmune disease." The Oxford Companion to the Body. 2001. Encyclopedia.com. (June 26, 2016). http://www.encyclopedia.com/doc/1O128-autoimmunedisease.html

COLIN BLAKEMORE and SHELIA JENNETT. "autoimmune disease." The Oxford Companion to the Body. 2001. Retrieved June 26, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O128-autoimmunedisease.html

Autoimmune Disease

Autoimmune Disease

In order for the immune system to protect the body against attack by foreign organisms, it must be able to distinguish between the body's own proteins (autoantigens) and proteins from foreign cells (foreign antigens ). When the immune system turns against autoantigens, thus attacking its own tissues, the resulting condition is an autoimmune disease.

Common autoimmune diseases include:

  • glomerulonephritis, which compromises the filtering ability of the kidney tubules
  • Graves' disease, which stimulates the thyroid to overproduce thyroid hormone
  • rheumatoid arthritis, which destroys joint tissue
  • myasthenia gravis, which interferes with nerve-muscle communication
  • multiple sclerosis, which destroys the fatty myelin coating of nerves
  • systemic lupus erythematosus, which attacks deoxyribonucleic acid (DNA), causing widespread damage in kidneys, heart, lungs, and skin
  • juvenile onset (Type I) diabetes mellitus, which destroys the insulin-producing beta cells of the pancreas, resulting in inability to regulate blood sugar properly.

Theories of Autoimmunity

The cells involved in immune reactions are B lymphocytes (B cells), which develop in the bone marrow, and T lymphocytes (T cells ), which develop in the thymus. Each lymphocyte carries a recognition site for a specific antigen and becomes activated when that antigen is encountered. During development, most of the lymphocytes that could recognize and destroy widely occurring autoantigens are deleted. Tissues bearing these autoantigens are generally safe from subsequent attack by the immune system unless either the autoantigen mutates or the immune system confuses the autoantigen with a foreign antigen. However, some tissue-specific autoantigens are unavailable when lymphocytes are developing in the bone marrow or thymus, and so lymphocytes with receptors for those autoantigens remain viable, posing the threat of tissue destruction in autoimmune diseases.

It is not yet clear why these lingering, self-reactive lymphocytes do not trigger autoimmunity more often, or why autoimmunity occurs when it does. However, there is strong suspicion that infection may play an important role in genetically susceptible individuals. An infection causes the production of inflammatory chemicals. If these are present at the same time that a lymphocyte is presented with its autoantigen by an antigen-presenting cell, the combination could activate self-reactive lymphocytes that were not deleted during development. Destruction of body tissues bearing those autoantigens would follow.

In another possible process, termed "molecular mimicry," a foreign protein bears such similarity to an autoantigen that B cell antibodies or cytotoxic T cells specific for that foreign antigen cross-react with autoantigens, causing tissue destruction. Alternatively, the combination of a foreign antigen with a self-protein can form a new complex capable of activating appropriate T or B lymphocytes to destroy tissues containing the complex.

see also Antibody; Blood Sugar Regulation; Immune Response; T Cells

Patricia L. Dementi

Bibliography

Janeway, Charles A., Jr., Paul Travers, Mark Walport, and J. Donald Capra. Immunobiology: The Immune System in Health and Disease, 4th ed. New York: Elsevier Science Ltd./Garland Publishing, 1999.

Marieb, Elaine Nicpon. Human Anatomy and Physiology, 5th ed. San Francisco: Benjamin Cummings, 2001.

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autoimmune disease

autoimmune disease, any of a number of abnormal conditions caused when the body produces antibodies to its own substances. In rheumatoid arthritis, a group of antibody molecules called collectively RF, or rheumatoid factor, is complexed to the individual's own gamma globulin blood proteins; the circulating complex apparently causes tissue inflammation and muscle and bone deformities. In Hashimoto's thyroiditis, an inflammatory disease of the thyroid gland, antibodies are produced against the thyroid protein thyroglobulin. In some blood disorders, antibodies may be produced against the body's own red and white blood cells. Myasthenia gravis, a disease characterized by weakened muscles, is thought to have an autoimmune origin. In systemic lupus erythematosus it has been shown that individuals have antibodies to certain of their own body substances that for some reason are acting as antigens; these substances include the individual's own nucleic acids and cell organelles such as ribosomes and mitochondria. Lupus can cause dysfunction of many organs, including the heart, kidneys, and joints. Because lupus and certain diseases of probable autoimmune origin, e.g., scleroderma and dermatomyositis, affect collagen (connective tissue) throughout the body and blood vessels, they are referred to as collagen-vascular diseases. In rheumatic fever, the individual produces antibodies to antigens of streptococcal bacteria; it is believed that the streptococcal antigens are structurally similar to antigens of the heart and that antistreptococcal antibodies, combining with antigenic sites on the heart, damage the muscle and heart valves. Diseases of the immune system are currently treated by a variety of nonspecific immunosuppressive drugs and steroids.

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Autoimmune Disorders

AUTOIMMUNE DISORDERS

DEFINITION


Autoimmune disorders are conditions in which a person's immune system (the network of organs, tissues, cells, and chemicals whose job it is to protect the body from foreign invaders, like bacteria and viruses) attacks the body's own cells. As cells are killed, tissues begin to die off.

DESCRIPTION


Many forms of autoimmune disorders are now recognized. These disorders are classified as general or organ specific. A general autoimmune disorder is one that attacks a number of tissues throughout the body. An organ specific disorder attacks only one type of organ at a time.

Some examples of autoimmune disorders include:

  • Systemic lupus erythematosus (pronounced LOO-puhs er-uh-THEM-uhtuhs; see lupus entry) is a general autoimmune disorder. The condition occurs primarily in young and middle-aged women.
  • Rheumatoid (pronounced ROO-muh-toid) arthritis (see arthritis entry) is inflammation of joints. It occurs when the immune system attacks and destroys tissue that lines the bone joints and cartilage.
  • Goodpasture's syndrome is an inflammation of the lungs and kidneys. It occurs primarily in young males.
  • Grave's disease affects the thyroid gland. The diseases causes the gland to make an excessive amount of thyroid hormone.
  • Hashimoto's thyroiditis also affects the thyroid gland. But it causes a reduction in the amount of thyroid hormone produced by the gland.
  • Pemphigus vulgaris (pronounced PEM-fi-guhs vuhl-GARE-uhs) is a group of autoimmune disorders that affects the skin.
  • Myasthenia (pronounced MY-uhs-THEE-nee-uh) gravis is caused when messages from nerve cells to muscles are disrupted. Muscles become weakened.
  • Scleroderma (pronounced SKLEER-uh-DIR-muh) causes a toughening and hardening of connective tissue.
  • Autoimmune hemolytic anemia is a condition that causes damage to red blood cells (see anemia entry).
  • Autoimmune thrombocytopenic purpura (pronounced THROM-buh-SI-tuh-PEE-nick PIR-puh-ruh) results in destruction to blood platelets, cells that help blood to clot.
  • Pernicious anemia develops when the body can no longer make use of vitamin B12, resulting in a decreased production of red blood cells (see anemia entry).
  • Sjögren's (pronounced SHO-grenz) syndrome occurs when glands are damaged, increasing the loss of water by the body and causing excessive dryness.
  • Ankylosing spondylitis (pronounced ANG-kuh-lozing spon-duh-LIE-tis) results in the destruction of joints and soft tissue in the spine.
  • Vasculitis is a group of disorders in which blood vessels are destroyed.
  • Type I diabetes mellitus (see diabetes mellitus entry) is caused when the islet cells of the pancreas are damaged, preventing the release of insulin to the body.

CAUSES


Autoimmune disorders occur when the body's immune system becomes confused. Because the immune system is used to fight foreign invaders, under normal circumstances, the immune system is able to tell if a group of cells is part of the body or not. For example, it generally has no problem recognizing that bacteria and viruses do not belong to the body. In such cases, the immune system takes a number of actions to fight off and kill the foreign cells.

Autoimmune Disorders: Words to Know

Anemia:
A medical condition caused by a reduced number of red blood cells, characterized by general weakness, paleness, irregular heart beat, and fatigue.
Antibody:
A chemical made by the immune system to destroy foreign invaders.
General autoimmune disorder:
An autoimmune disorder that involves a number of tissues throughout the body.
Immune system:
A network of organs, tissues, cells, and chemicals designed to fight off foreign invaders, such as bacteria and viruses.
Organ specific disorder:
An autoimmune disorder in which only one type of organ is affected.
Steroids:
A group of naturally occurring substances that are very effective in reducing pain and swelling in tissues.

An important component of the immune system is the production of antibodies. Antibodies are chemicals made by the immune system to destroy foreign invaders. Antibodies are very specific. The immune system makes only one type of antibody for each different foreign invader. For example, there is a very specific antibody for each different virus that gets into the body.

But the immune system sometimes makes mistakes. It may somehow regard cells from its own body as being foreign. In such cases, it takes the same actions against those cells as it does against bacteria, viruses, and other truly foreign organisms. It actually begins to destroy healthy, normal cells in the body. When this happens, an autoimmune disorder results.

ORGAN TRANSPLANTATION

An organ transplantation may be necessary when a person's heart, kidney, lungs, liver, or some other vital organ becomes diseased. In such cases, a second person may offer to donate his or her organ to replace the diseased or damaged organ. Autoimmune disorders can often occur when organs are transplanted from one person to another. The problem is that the patient's immune system may reject the donated organ because it thinks the donated organ is a foreign body. It begins to attack the new organ as it would bacteria, viruses, fungi, or other disease-causing organisms.

Patients who receive transplanted organs are also given immunosuppressant drugs. An immunosuppressant drug is a chemical that reduces the body's natural defenses against foreign bodies. It gives the donated organ a chance to become implanted in the new body and start functioning again.

However, immunosuppressant drugs can cause a different set of problems: they prevent the immune system from doing its normal jobs; a patient becomes much more sensitive to diseases that the immune system is usually able to fight; and patients may become ill very easily. For most patients, though, the tradeoff is well worth it. Without the new, healthy organ and the immunosuppressant drugs to sustain it, they might not live.

SYMPTOMS


Each type of autoimmune disorder has its characteristic symptoms. Some of these symptoms include:

  • Systemic lupus erythematosus: Fever, chills, fatigue, weight loss, skin rashes, patchy hair loss, sores in the mouth or nose, problems with the digestive system, vision problems and, in women, irregular periods. Lupus can also affect the central nervous system, causing seizures, depression, and mental disorders.
  • Rheumatoid arthritis: Mild fever, loss of appetite, weight loss, and, most important, pain in the joints. In advanced stages, rheumatoid arthritis can lead to deformities of the body.
  • Goodpasture's syndrome: Fatigue and paleness. Bleeding may occur in the lungs or the urinary system.
  • Grave's disease: An enlarged thyroid gland, weight loss, sweating, irregular heart beat, nervousness, and an inability to tolerate heat.
  • Hashimoto's thyroiditis: Generally no symptoms.
  • Pemphigus vulgaris: Blisters and deep, open sores on the skin.
  • Myasthenia gravis: General muscle weakness that may develop into paralysis. Chewing, swallowing, and breathing may be difficult.
  • Scleroderma: Pain, swelling, and stiffness of the joints. The skin takes on a tight, shiny appearance. Digestive problems may develop, leading to weight loss, loss of appetite, diarrhea, constipation, and swelling of the abdomen.
  • Autoimmune hemolytic anemia: Fatigue and tenderness in the abdomen.
  • Autoimmune thrombocytopenic purpura: Tiny, red dots on the skin, unexplained bruises, bleeding from the nose and gums, and blood in the stool.
  • Pernicious anemia: General weakness, sore tongue, bleeding gums, and tingling in the arms and legs. A deficiency of vitamin B12 can also cause a number of nervous disorders, including weakness, lack of coordination, blurred vision, loss of the sense of taste, ringing in the ears, and loss of bladder control.
  • Sjögren's syndrome: Excessive dryness of the mouth and eyes.
  • Ankylosing spondylitis: Lower back pain that usually moves up the spine.
  • Vasculitis: Symptoms range widely depending on the part of the body affected.
  • Type I diabetes mellitus: Fatigue and an abnormally high level of sugar in the blood.

DIAGNOSIS


The first step in diagnosing any autoimmune disorder is usually a review of symptoms. An additional step involves ruling out other medical conditions that might produce similar symptoms.

The final diagnosis for an autoimmune disorder, however, usually involves a blood test. The purpose of the blood test is to look for antibodies. If ankylosing spondylitis is present in the body, for example, very specific antibodies for that disorder will be present. If no such antibodies are found in the patient's blood, the disorder is not present.

TREATMENT


Treatments differ for each type of autoimmune disorder. However, there is one treatment that is common to many forms of autoimmune disorders. That treatment is the use of drugs to reduce the inflammation, swelling, and pain that accompanies most autoimmune disorders. Inflammation occurs when antibodies attack and irritate tissues. Some common drugs, such as aspirin and ibuprofen (pronounced i-byoo-PRO-fuhn), help reduce inflammation and pain. Aspirin should not be given to children due to the danger of contracting Reye's syndrome (see Reye's syndrome entry). A more powerful medication is one of the many steroid medications. But steroids have some serious long-term side effects, and they are generally used only in severe cases or in situations where milder drugs are ineffective.

PROGNOSIS


Prognosis differs for each type of autoimmune disorder.

PREVENTION


There is currently no way to prevent any of the autoimmune disorders.

See also: Anemias, arthritis, diabetes, and lupus.

FOR MORE INFORMATION


Books

Aaseng, Nathan. Autoimmune Diseases. New York: Franklin Watts, 1995.

Organizations

American Autoimmune Related Diseases Association, Inc. 15475 Gratiot Avenue, Detroit, MI 48205. (313) 3718600. http://www.aarda.org.

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autoimmune disease

autoimmune disease Any one of a group of disorders caused by the body's production of antibodies which attack the body's own tissues. One example of such an autoimmune disease is systemic lupus erythematosus (SLE), an inflammation of the connective tissue occurring most often in young women. The occasional presence of so-called auto-antibodies in an individual does not necessarily indicate autoimmune disease.

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autoimmune disease

autoimmune disease (aw-toh-i-mewn) n. one of a group of otherwise unrelated disorders caused by inflammation and destruction of tissues by the body's own immune response. These disorders include pernicious anaemia, rheumatic fever, rheumatoid arthritis, glomerulonephritis, myasthenia gravis, and Hashimoto's disease.

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