In autoimmune diseases the activity of the immune system is directed against the patient’s own body. A typical feature of this is the appearance of “autoantibodies”. In contrast to antibodies which are directed against infectious pathogens that have invaded, autoantibodies target body cells and can disrupt their function.
A distinction is made between diseases which affect only one organ, and diseases which extend to several organs and the vascular system (systemic autoimmune diseases).
Autoimmune diseases can take an acute or a chronic course.
In acute diseases a sudden increase in the concentration of autoantibodies and an uncontrolled inflammatory activity are responsible for the symptoms that appear. Acute autoimmune diseases are confined to one organ (e.g. the blood and system of blood vessels, the peripheral nervous system).
Chronic autoimmune diseases are characterised by persistent disorders of the immune system. They may affect a single organ or several organs at the same time. A typical feature is the formation of T and B cell clones (an accumulation of cells of the same type) directed against the patient’s own body. These cell clones then bind almost exclusively autoantigens and autoantibodies, and are therefore also unavailable to the body’s immune defence against foreign pathogens.
The treatment of autoimmune diseases
The objective of the treatment of autoimmune diseases is a rapid reduction in the unwanted inflammatory activity. In addition, the formation of new autoantibodies should be prevented. This is achieved by influencing cell activity.
We have at our disposal immunosuppressants (corticosteroids and cytostatics), immunomodulators (e.g. intravenous immunoglobulins) and blood exchange techniques (plasmaphaeresis, immuno-adsorption).
Which of these therapeutic options is chosen depends on the severity of the disease (organ involvement, functional impairment) and the speed with which the disease is progressing. If permanent therapy is necessary, as is often the case in chronic autoimmune diseases, different therapies are combined.
Intravenous immunoglobulins influence the activity of the cells step by step, but do not stop them completely. The immune response to foreign pathogens is thereby preserved.
In acute, rapidly progressing or severe inflammation-mediated autoimmune diseases, immunoglobulins are given in high doses and usually lead to a clinical improvement within a few days. The diseases in which immunoglobulins are recommended as the first-line therapy include immune thrombocytopenia (ITP), Guillain-Barré syndrome (GBS), and Kawasaki syndrome.
In chronic autoimmune diseases intravenous immunoglobulins are given to supplement immunosuppressant therapies (for example corticosteroids). They assist the regeneration of destroyed tissue, bind inflammatory substances and ensure their more rapid destruction. They serve in addition to maintain the patient’s defences against infection.