Immune system: The body mechanisms that fight disease by recognizing and neutralizing foreign cells.

Immunotherapy: A form of therapy that stimulates the immune system to kill or control cancer cells. Also called biochemical therapy or biotherapy.

Interferon alpha: See alpha interferon.

Interferons: Proteins produced naturally by white blood cells that stimulate the growth of certain disease-fighting blood cells in the immune system. Manufactured forms of interferons are used in cancer immunotherapy to improve the body's natural response to disease.

Interleukin-2 (IL-2): An agent that stimulates the growth of specific types of white blood cells; used in cancer immunotherapy.

Interleukins: Special proteins released by the immune system to fight bacteria, viruses, and other foreign substances.

Intravenous (IV): Into a vein.

INTRON® A (Interferon alfa-2b, recombinant) for Injection: A medication used in the therapy of malignant melanoma.

Immunosuppression: Immunosuppression is a disorder or condition where the immune response is reduced or absent.

Ischemic: Not getting enough blood flow.

Isolated limb perfusion: A procedure in which anticancer drugs are injected directly into an arm or leg and the blood to and from that limb is cut off for a short period of time.