The immune system protects the body from potentially harmful substances (antigens), such as microorganisms, toxins and foreign blood or tissues from other organisms.
When an antigen enters the body, the immune system produces antibodies that bind to the antigen. Then sensitized lymphocytes (specialized white blood cells that recognize and destroy specific antigens) engulf the foreign substance in a process called phagocytosis.
Autoimmune disorders are conditions caused by an immune response against the body's own tissues. The immune system mistakes its own cells for antigens. Autoimmunity is present in all healthy individuals, to some extent. However, healthy individuals are able to suppress defective lymphocytes (immune system cells) that mistakenly destroy body cells.
Autoimmune disorders can destroy body tissues, cause abnormal organ growth or impair organ function. Autoimmune disorders commonly affect blood components (like red blood cells, connective tissues and blood vessels), endocrine glands (like the thyroid or pancreas), as well as muscles, joints and the skin.
A person may experience more than one autoimmune disorder at the same time. Researchers estimate that at least 10 million Americans suffer from at least one of the more than 80 illnesses caused by autoimmunity. Examples of some of the most prominent autoimmune disorders include, Hashimoto's thyroiditis (inflamed thyroid that often causes underactive thyroid function), pernicious anemia (lack of vitamin B12 absorption), Addison's disease, type I diabetes, rheumatoid arthritis, systemic lupus erythematosus, dermatomyositis, Sjögren's syndrome, lupus erythematosus, multiple sclerosis (MS), myasthenia gravis, Reiter's syndrome, Grave's disease and celiac disease.
The prognosis for individuals with autoimmune disorders depends on the specific disorder. Most autoimmune disorders are chronic (long-term). However, many disorders can be managed with treatment, including immunosuppressants and anti-inflammatories.

Related Terms

Addison's disease, allergic, allergy, ankylosing spondylitis, antibody, antigen, apoptosis, blood vessels, celiac disease, connective tissue, c-reactive protein, dermatomyositis, erythrocyte sedimentation rate, ESR, FANA, fluorescent antinuclear antibody, Grave's disease, Hashimoto's thyroiditis, histocompatibility, hypersensitivity, immune, immune disease, immune disorder, immune system, immunity, immunoglobulin, immunosuppressants, immunosuppression, inflammation, intravenous immunoglobulin, IVIG, major histocompatibility complex, leukocytes, lupus, lymphocytes, MHC, MS, multiple sclerosis, myasthenia gravis, pernicious anemia, programmed cell death, red blood cells, Reiter's syndrome, rheumatoid arthritis, sensitized, sensitized lymphocytes, Sjögren's syndrome, systemic lupus erythematosus, type I diabetes, white blood cells.