|Friday, 27 August 2010 11:23|
What is Autoimmunity?
One of the functions of the immune system is to protect the body by responding to invading microorganisms, such as viruses or bacteria, by producing antibodies or sensitized lymphocytes (types of white blood cells). Under normal conditions, an immune response cannot be triggered against the cells of one's own body.
In certain cases, however, immune cells make a mistake and attack the very cells that they are meant to protect. This can lead to a variety of autoimmune diseases. They encompass a broad category of related diseases in which the person's immune system attacks his or her own tissue.
What causes Autoimmunity?
The immune system normally can distinguish "self" from "non-self." Some lymphocytes are capable of reacting against self, resulting in an autoimmune reaction. Ordinarily these lymphocytes are suppressed. Autoimmunity occurs naturally in everyone to some degree; and in most people, it does not result in diseases.
Autoimmune diseases occur when there is some interruption of the usual control process, allowing lymphocytes to avoid suppression, or when there is an alteration in some body tissue so that it is no longer recognized as "self" and is thus attacked. The exact mechanisms causing these changes are not completely understood; but bacteria, viruses, toxins, and some drugs may play a role in triggering an autoimmune process in someone who already has a genetic (inherited) predisposition to develop such a disorder. It is theorized that the inflammation initiated by these agents, toxic or infectious, somehow provokes in the body a "sensitization" (autoimmune reaction) in the involved tissues.
What are the types of Autoimmunity?
Particular autoimmune disorders are frequently classified into organ-specific disorders and non-organ-specific types. Autoimmune processes can have various results, for example, slow destruction of a specific type of cells or tissue, stimulation of an organ into excessive growth, or interference in its function.
Organs and tissues frequently affected include the endocrine gland, such as thyroid, pancreas, and adrenal glands; components of the blood, such as red blood cells; and the connective tissues, skin, muscles, and joints. Some autoimmune diseases fall between the two types. Patients may experience several organ-specific diseases at the same time. There is, however little overlap between the two ends of the spectrum.
In organ-specific disorders, the autoimmune process is directed mostly against one organ. Examples, with the organ affected, include Hashimoto's thyroiditis (thyroid gland), pernicious anemia (stomach), Addison's disease (adrenal glands), and type 1 diabetes (pancreas). In non-organ-specific disorders, autoimmune activity is widely spread throughout the body. Examples include rheumatoid arthritis, systemic lupus erythematosus (SLE or lupus), and dermatomyositis.
What are some of the treatments for autoimmune diseases?
Of first importance in treating any autoimmune disease is the correction of any major deficiencies. An example would be replacing hormones that are not being produced by the gland, such as thyroxin in autoimmune thyroid disease or insulin in type 1 diabetes. In autoimmune blood disorders, treatment may involve replacing components of the blood by transfusion.
Second in importance is the diminishing of the activity of the immune system. This necessitates a delicate balance, controlling the disorder while maintaining the body's ability to fight disease in general. The drugs most commonly used are corticosteroid drugs. More severe disorders can be treated with other more powerful immunosuppressant drugs, such as methotrexate, cyclophosphamide, and azathioprine. All of these drugs, however, can damage rapidly dividing tissues, such as the bone marrow, and so are used with caution.
Intravenous immunoglobulin therapy is used in the treatment of various autoimmune diseases to reduce circulating immune complexes. Some mild forms of rheumatic autoimmune diseases are treated by relieving the symptoms with nonsteroidal anti-inflammatory medications. Drugs that act more specifically on the immune system, for example, by blocking a particular hypersensitivity reaction, are being researched.
What is the family connection in autoimmune diseases?
The ability to develop an autoimmune disease is determined by a dominant genetic trait that is very common (20 percent of a population) that may present in families as different autoimmune diseases within the same family. The genetic predisposition alone does not cause the development of autoimmune diseases. It seems that other factors need to be present as well in order to initiate the disease process. It is important for families with members who have an autoimmune disease to mention this fact when another member of the family is experiencing medical problems that appear to be difficult to diagnose.
For more information on Autoimmunity, visit the American Autoimmune Related Diseases Association