IN 2003, Newsweek magazine declared autoimmune disease one of the top 10 health stories. There are actually more than 80 types of autoimmune diseases. According to the National Institutes of Health in the United States, approximately 23.5 million Americans have 24 of the 80 recognised autoimmune disorders, making the prevalence of autoimmune disease greater than cancer and roughly equal to heart disease. More than 75 per cent of those affected are women. The prevalence is rising.

Our bodies have an immune system that protects us from disease and infection. The immune system is the body's means of protection against harmful substances such as microorganisms, toxins, cancer cells, and foreign blood or tissues from another person or species (antigens) The immune system is composed of two major parts.

One component is the production of antibodies, proteins that attack antigens and cause them to be removed from the body; this is sometimes called the humoral immune system. The other component is composed of special blood cells, called T lymphocytes, that can attack antigens - this is sometimes called the cellular immune system.

Normally, the immune system is capable of differentiating "self" from "non-self" tissue. Some immune system cells (lymphocytes) become sensitised against "self" tissue cells, but these faulty lymphocytes are usually controlled by other lymphocytes. Autoimmune disorders occur when the normal control process is disrupted. They may also occur if normal body tissue is altered so that it is no longer recognised as "self".

What are autoimmune disorders?

Autoimmune disorders result in the destruction of one or more types of body tissues, abnormal growth of an organ, or changes in organ function. The disorder may affect only one organ or tissue type (localised), or may affect multiple organs and tissues (systemic). Organs and tissues commonly affected by autoimmune disorders include red blood cells, blood vessels, connective tissues, which bind together body tissues and organs, endocrine glands such as the thyroid or pancreas, nerve, muscles, joints, and skin.

The effect of localised autoimmune disorders, however, can be systemic as they frequently have an indirect effect on other body organs and systems. Systemic Autoimmune Diseases include Rheumatoid arthritis (joints, less commonly lung, skin); Systemic Lupus Erythematosus, SLE (skin, joints, kidneys, heart, brain, red blood cells); Scleroderma (skin, intestine, lung); Sjogren's syndrome (salivary and tear glands, joints).

Localised autoimmune diseases include Type 1 Diabetes Mellitus (pancreas); Hashimoto's thyroiditis, Graves' disease (thyroid); Rheumatic fever (heart valves); Celiac disease, Crohn's disease, Ulcerative colitis (gastrointestinal tract); Multiple sclerosis; Guillain-Barre syndrome (central nervous system); Addison's disease (adrenal); alopecia areata (hair follicles); endometriosis. In some cases, a person may have more than one autoimmune disease, for example, persons with Addison's disease often have type 1 diabetes.

Possible causes

The cause of autoimmune diseases is unknown, but it appears that there is an inherited predisposition to develop autoimmune disease in many cases. In a few types of autoimmune disease (such as rheumatic fever), a bacteria or virus triggers an immune response, and the antibodies or T-cells attack normal cells because they have some part of their structure that resembles a part of the structure of the infecting germ.

Research is shedding light on genetic as well as hormonal and environmental risk factors that contribute to the causes of these diseases.
For unknown reasons, about 75 per cent of autoimmune diseases occur in women, most frequently during the childbearing years. Some of these diseases also affect African American, American Indian, and Latina women more than white women.

Hormones are thought to play a role, because some autoimmune illnesses occur more frequently after menopause, others suddenly improve during pregnancy, with flare-ups occurring after delivery, while still others will get worse during pregnancy
Autoimmune diseases also seem to have a genetic component, but, mysteriously, they can cluster in families as different illnesses.

For example, a mother may have lupus erythematosus; her daughter, diabetes; her grandmother, rheumatoid arthritis. With the exception of thyroid disease, diabetes, and SLE, individually these diseases are not common. However, taken as a whole, they represent the fourth-largest cause of disability among women in the United States.

Although genes are important, they are not the only answer to the mystery of autoimmunity. Many persons who have a family member with an autoimmune disease will never develop one; while others with one autoimmune disease never get a second one. People with genetic types that are known to be associated with certain diseases never develop the disease. This indicates that the culprit genes must have an accomplice - a "trigger". That accomplice is thought to be environmental. The trigger appears to vary for different diseases and possibly even for different people with the same disease.

For some diseases, the trigger is known. For example, in rheumatic heart disease, a disease in which the immune system attacks the heart valves, the trigger is streptococcus bacterial infection. If the immune system becomes activated to fight the original infection and somehow fails to turn off when the streptococcus bacterium is eradicated, it may mistakenly attack and damage the heart valves as if they, too, were a dangerous invader.

This is thought to happen because something about the genetic make-up of the cellular matter of the heart valves is similar to the make-up of the strep bacterium - this phenomenon is called molecular mimicry.
For other diseases, the triggers are less certain, but may include hormones, exposure to solvents and chemicals, and in the case of lupus, even sunlight exposure. In some cases, there may be a sequence of triggers. In other words, an infection that occurs early in life sets the stage for an autoimmune disease, but stays quiet until a second infection comes along and rouses it into development.

Autoimmune disease may be precipitated by stress, the Epstein barr virus, exposure to mercury, volatile organic compounds or silica dust. It is thought that vitamin D deficiency, cow's milk fed to infants may also play a role. Not to be left out of the picture are cigarette smoking, man-made environmental oestrogens such as DDT, polychlorinated biphenyls (PCBs), dioxin along with bisphenol A (BPA, phthalates and poly-brominated diphenylethers (PBDE) - the latter trio are practically unavoidable in societies awash in plastics.

Symptoms

Symptoms of autoimmune disease vary widely depending on the type of disease. A group of very non-specific symptoms often accompany autoimmune diseases, especially of the collagen vascular type, and include fatigue, dizziness, malaise and low-grade fever. Symptoms will vary with the specific disorder and the organ or tissue affected.

Specific autoimmune disease results in:
. Destruction of an organ or tissue resulting in decreased functioning of an organ or tissue (for example, the islet cells of the pancreas are destroyed in diabetes).
. Increase in size of an organ or tissue (for example, thyroid enlargement in Grave's Disease).

Treatment

The goals of treatment are to bolster the immune system, reduce symptoms and control the autoimmune process while maintaining the ability to fight disease.

Dr Jacqueline E Campbell is a family physician in private practice Email: drjcampbell14@yahoo.com.

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