The immune system is essential to survival, and even a modest decrease in immune function can leave a person susceptible to infection. But the immune system itself can also cause disease, by inappropriately attacking the body’s own organs, tissues, or cells.
More than 80 autoimmune diseases have been described to date. Some, such as type 1 diabetes, attack specific organs, while others, such as systemic lupus erythematosus (SLE), involve multiple organs. Although many autoimmune diseases are rare, collectively they affect approximately 5 to 8 percent of the U.S. population. A disproportionate number of people with autoimmune disorders are women. For unknown reasons, the prevalence of autoimmune diseases is increasing.
SOURCE: National Institute of Allergy and Infectious Diseases