Autoantibodies

What are they?

Antibodies are proteins produced by a person's immune system that help the body to recognise and get rid of infection. Autoantibodies are antibodies that recognise parts of our own body. Autoantibodies can be found in healthy people, particularly as we get older, but they are also found in some autoimmune diseases. In a few specific diseases, autoantibodies are actually causing the disease e.g. Grave’s disease, myasthenia gravis. 

As the immune system develops, it learns how to recognise components of our own body and ignore them (“self”). There are also regulatory mechanisms that prevent the immune system attacking “self”. However, sometimes these processes fail and the immune system may start attacking our own body, resulting in inflammation and damage, and causing autoimmune disease. Autoantibodies can be a marker of the disease e.g. tissue transglutaminase antibodies in coeliac disease, or can be actually causing the disease directly e.g. by acting on the thyroid gland, resulting in Grave’s disease. 

The reasons that autoimmune diseases develop are not completely understood, but are thought to involve 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. 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 immune system. Disorders 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. Autoimmune diseases that affect multiple organs or systems, called systemic autoimmune disease, 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 non-specific e.g. arthritis-type joint pain, fatigue, fever, rashes, cold or allergy-type symptoms, weight loss, and muscle pain or 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 autoantibody. These circumstances can make it difficult to identify the primary cause and arrive at a diagnosis.