Autoantibodies

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What are they?

Antibodies are proteins produced by a person's immune system that allows the body to to distinguish between "self" and "non-self" proteins. Autoantibodies are antibodies that actually target and damage specific tissues or organs of the body.

Usually the immune system is able to discriminate between foreign substances ("non-self") and the body’s own cells ("self"). It produces antibodies only when it perceives that what it has been exposed to is a threat ("non-self"). When the immune system ceases to recognise one or more of the body's normal constituents as "self," it may produce autoantibodies that attack its own cells, tissues, and/or organs, causing inflammation and damage. A person’s immune system may produce one or more autoantibodies against different “self” targets

The causes of autoimmunity are varied and are not well understood. In many instances, autoantibody production can be linked to a to a genetic predisposition combined with an environmental trigger, such as a viral illness or a prolonged exposure to certain toxic chemicals. Some families have a high prevalence of autoimmune conditions; however, individual family members may have different autoimmune disorders or may never develop one. Researchers believe that there may also be a hormonal component, as many autoimmune conditions are more common in women of childbearing age.

The type of autoimmune disorder or disease that occurs and the amount of destruction done to the body depends on which systems or organs are targeted by the autoantibodies. Disorders caused by autoantibodies that primarily affect a single organ, such as the thyroid in Graves disease or Hashimoto thyroiditis, are often easier to diagnose as they frequently present with organ-related symptoms.

Disorders due to systemic autoantibodies, which affect multiple organs or systems, can be much more difficult to diagnose and hence there can sometimes be delays in diagnosis. The signs and symptoms they cause can be multifold and may include: arthritis-type joint pain, fatigue, fever, rashes, cold or allergy-type symptoms, weight loss, and muscular weakness. Additional complications may include vasculitis and anaemia. Signs and symptoms will vary from person to person and they can vary over time, tapering off and then flaring up unexpectedly. To complicate the situation, some people may have more than one autoantibody or even more than one autoimmune disorder. There are also people who have an autoimmune disorder without a detectable level of an autoantibody. These circumstances can make it difficult to identify the prime cause and arrive at a diagnosis.

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