Therapeutic uses of interleukin-2 and lymphokine-activated killer (LAK) cells

Interleukin-2 (IL-2) is the first of a growing list of lymphokines to be cloned and available for preclinical and clinical evaluation. A product of T-helper lymphocytes, IL-2 augments the cytolytic activity of T-lymphocytes and natural killer (NK) cells, stimulates the proliferation of these cells, and induces the formation of lymphokine-activated killer (LAK) cells. LAK cells exhibit cytolytic activity against a broad range of both freshly isolated and cultured tumor cells, while exhibiting limited cytolytic activity against normal cells. The apparently large therapeutic index suggested by in vitro studies is strongly supported by the antitumor responses seen in preclinical studies. Initial clinical studies reported encouraging response rates, but the actual role of IL-2 and/or LAK cell infusion in cancer therapy has yet to be determined, and may only represent the first step in managing the tumoricidal potential of the immune system.