Autoimmune disease

Overview
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 attacks its own cells. This may be restricted to certain organs (e.g. in 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.

Occurrence and onset
Hormone levels have been shown to affect the severity of some autoimmune diseases such as multiple sclerosis. Other causes may include the presence of fetal cells in the maternal bloodstream, i.e. microchimerism.

Autoimmune diseases
It is possible to classify autoimmune diseases by corresponding type of hypersensitivity: type II, type III, or type IV. (No type of autoimmune disease mimics type I hypersensitivity.)

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.

Currently, a considerable amount of research is being conducted into treatment of these conditions. According to a report from Frost & Sullivan, the total alliance payouts in the autoimmune/inflammation segment from 1997 to 2002 totaled $489.8 million, where Eli Lilly, Suntory, Procter & Gamble, Encysive, and Novartis together account for 98.6 percent of alliance payouts.