Disorders of the immune system can result in abnormally low or abnormally high immune system activity. In the presence of an overactive immune system, the body attacks and destroys its own tissues (autoimmune disease). Immunodeficiency diseases reduce the body’s ability to fight off external invasions, causing the body to be vulnerable to infection.
Triggered by unknown factors, the immune system may produce certain antibodies. These antibodies do not fight the infection, but instead attack the body’s own tissues. Treatment of autoimmune diseases generally focuses on reducing the activity of the immune system.
Autoimmune diseases include:
Rheumatoid arthritis
The immune system produces antibodies that attach to the inner layers of the joints. The immune system cells then attack the joints, causing inflammation, swelling, and pain. If left untreated, rheumatoid arthritis can gradually lead to permanent joint damage. Rheumatoid arthritis can be treated with a variety of drugs taken orally or injected to reduce the activity of the immune system.
Systemic lupus erythematosus (Lupus)
People with SLE produce autoimmune antibodies that can attach to tissues throughout the body. Symptoms often involve the joints, lungs, blood cells, nerves, and kidneys. A common treatment is daily oral prednisone, a steroid that reduces the function of the immune system.
Inflammatory bowel disease (IBD)
The immune system attacks the intestinal wall, causing symptoms such as diarrhea, rectal bleeding, rapid bowel movements, abdominal pain, fever, and weight loss. The two main forms of inflammatory bowel disease are ulcerative colitis and Crohn’s disease. Oral and injectable immunosuppressive drugs are used to treat inflammatory bowel disease.
Multiple sclerosis (MS)
The immune system attacks nerve cells, causing symptoms including pain, blindness, weakness, poor coordination, and muscle spasms. Various drugs that suppress the immune system are used to treat multiple sclerosis.
Type 1 diabetes
The immune system produces antibodies that attack and destroy the insulin-producing cells in the pancreas. Young people with type 1 diabetes need insulin injections to survive.
Green-Barre syndrome
The immune system attacks the nerve tissue that controls the muscles in the legs, and sometimes the arms and upper body. The disease causes weakness in patients, sometimes with very serious consequences. The main treatment for Guillain-Barre syndrome is filtering the patient’s blood with plasmapheresis.
Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)
Similar to Guillain-Barre syndrome (GBS), the patient’s immune system attacks the nervous system, but the symptoms last much longer. If not diagnosed and treated early, about 30% of patients are wheelchair dependent for mobility. Treatment for chronic inflammatory demyelinating polyradiculoneuropathy and Green-Barre syndrome is essentially the same.
Psoriasis
In psoriasis, overactive immune system T cells (a class of blood cells) accumulate on the skin. The activity of the immune system stimulates skin cells to multiply rapidly, producing silvery, scaly plaques on the skin.
Hyperthyroidism
The immune system produces antibodies that stimulate the thyroid gland to release excess thyroid hormone into the bloodstream (hyperthyroidism). Symptoms of hyperthyroidism disease include swollen eyes, weight loss, nervousness, irritability, rapid heart rate, weakness, and dry, brittle hair. Treatment of hyperthyroidism usually involves the use of medications or surgical methods to destroy or remove the thyroid gland.
Hashimoto’s thyroiditis
Antibodies produced by the immune system attack the thyroid gland, slowly destroying the cells that produce thyroid hormones. Levels of thyroid hormones are reduced (hypothyroidism) and usually last for months to years. Symptoms include fatigue, constipation, weight gain, depression, dry skin, and sensitivity to cold. Daily oral synthetic thyroid hormone pills can restore normal body function.
Myasthenia gravis
Antibodies bind to the nerves and prevent them from stimulating the muscles properly. The main symptom of myasthenia gravis is that the patient feels weaker after activity. Daly pills (bromipyridamole) are the main drug used to treat myasthenia gravis.
Vasculitis
In this type of autoimmune disease, the immune system attacks and destroys blood vessels. Vasculitis can affect any organ, so symptoms vary widely and can involve almost any part of the body. It is usually treated with prednisone or other corticosteroids that reduce the activity of the patient’s immune system.