Lupus is a disease in which the immune systems attacks healthy tissue.

An autoimmune disease is one in which the body's immune system mistakenly attacks healthy tissue, leading to long-term (chronic) inflammation.

U.S. regulators are also considering whether to approve use of Humira for psoriasis, a condition in which an overactive immune system attacks healthy tissue.

Lupus is a disease in which the immune system attacks healthy cells and tissues by mistake, leading to damaged joints, skin, blood vessels or organs.

A cytokin storm is a disastrous over-reaction of the immune system, when the immune system attacks healthy cells, and that can start in the brain.