Autoimmune Disorders

The immune system normally relies on a careful ability to distinguish the body's own cells and molecules ("self") from anything foreign ("non-self"), attacking only the latter. An autoimmune disorder occurs when this self/non-self recognition breaks down, and the immune system begins to treat some of the body's own healthy tissue as though it were a foreign antigen, mounting a sustained attack against it.

Because autoimmune disorders can, in principle, target almost any tissue in the body, they produce a wide range of conditions depending on which tissue is attacked. One of the best-known examples that specifically affects the joints is rheumatoid arthritis, in which the immune system attacks the tissue lining the joints, causing chronic inflammation, pain, swelling, and, over time, progressive joint damage if left unmanaged. Other autoimmune conditions target different tissues entirely — for instance, some affect the thyroid gland, and others affect the skin or the nervous system — but all share the same underlying pattern of the immune system turning against the body's own structures.