Autoimmune disease

Autoimmune diseases arise from an overactive immune response of the body against substances and tissues normally present in the body. In other words, the body actually attacks its own cells. The immune system mistakes some part of the body as a pathogen and attacks it. This may be restricted to certain organs (e.g. in autoimmune thyroiditis) or involve a particular tissue in different places (e.g. Goodpasture's disease which may affect the basement membrane in both the lung and the kidney). The treatment of autoimmune diseases is typically with immunosuppression&mdash;medication which decreases the immune response.

Criteria
For a disease to be regarded as an autoimmune disease, it needs to answer to Witebsky's postulates (first formulated by Ernst Witebsky and colleagues in 1957 and modified in 1993):
 * Direct evidence from transfer of pathogenic antibody or pathogenic T cells
 * Indirect evidence based on reproduction of the autoimmune disease in experimental animals, and
 * Circumstantial evidence from clinical clues

Classification
There is an on-going discussion about when a disease should be considered autoimmune, leading to different criteria such as Witebsky's postulates.

Development of therapies
In both autoimmune and inflammatory diseases the condition arises through aberrant reactions of the human adaptive or innate immune systems. In autoimmunity, the patient’s immune system is activated against the body's own proteins. In inflammatory diseases, it is the overreaction of the immune system, and its subsequent downstream signaling (TNF, IFN, etc.), which causes problems.

A substantial minority of the population suffers from these diseases, which are often chronic, debilitating, and life-threatening. There are more than eighty illnesses caused by autoimmunity. It has been estimated that autoimmune diseases are among the ten leading causes of death among women in all age groups up to 65 years.