Graves disease is an autoimmune disorder that involves overactivity of the thyroid gland (hyperthyroidism). Hallmarks of the condition are bulging eyes (exophthalmos), heat intolerance, increased energy, difficulty sleeping, diarrhea, and anxiety.

Chronic thyroiditis (Hashimoto's disease) is a slowly developing persistent inflammation of the thyroid which frequently leads to hypothyroidism, a decreased function of the thyroid gland. Middle-aged women are most commonly affected.

Multiple sclerosis is a central nervous system disorder marked by decreased nerve function with initial inflammation of the protective myelin nerve covering and eventual scarring. Symptoms and severity of symptoms vary widely and may progress into episodes of crisis alternating with episodes of remission.

Rheumatoid arthritis is an autoimmune disease in which the body's immune system attacks itself. The pattern of joints affected is usually symmetrical, involves the hands and other joints and is worse in the morning. Rheumatoid arthritis is also a systemic disease, involving other body organs, whereas osteoarthritis is limited to the joints. Over time, both forms of arthritis can be crippling.

Rheumatoid arthritis is a systemic autoimmune disease which initially attacks the synovium, a connective tissue membrane that lines the cavity between joints and secretes a lubricating fluid.

Systemic lupus erythematosus is a chronic inflammatory autoimmune disorder which may affect many organ systems including the skin, joints and internal organs. The disease may be mild or severe and life-threatening. African-Americans and Asians are disproportionately affected.

The synovial membrane is the inner membrane of tissue that lines a joint. The synovial membrane secretes synovial fluid which serves to lubricate the joint.

Rheumatoid arthritis is another form of arthritis. The body's own immune system attacks a joint's synovial membrane, which secretes fluid and lines the joint. The synovium becomes inflamed, produces excess fluid, and the cartilage becomes rough and pitted.

Antigens are large molecules (usually proteins) on the surface of cells, viruses, fungi, bacteria, and some non-living substances such as toxins, chemicals, drugs, and foreign particles. The immune system recognizes antigens and produces antibodies that destroy substances containing antigens.