Overview of interleukin-2 as an immunotherapeutic agent.

Interleukin-2 (IL-2) is a lymphokine which has a variety of in vivo immunomodulatory effects. The administration of IL-2 can mediate enhancement of cellular immune responses, induction of lymphocyte proliferation, production of cytokines, and regression of established tumor in animal models. The availability of large quantities of recombinant IL-2 has enabled investigators to examine its therapeutic potential in the treatment of human cancer. Several studies have documented the ability of IL-2 administration to cause durable tumor regression in patients with advanced melanoma and renal cell cancer. Toxicity of therapy is dose related and is mediated by a vascular capillary leak syndrome, lymphocytic infiltration, and the release of cytokines secreted in response to IL-2 administration. The side effects are completely reversible upon cessation of therapy. Future efforts are aimed at increasing the antitumor efficacy and decreasing the toxicity of IL-2 administration.