Interleukin-2 therapy for human cancer.

The concept of immunotherapy is evolving from nonspecific, haphazard stimulation of the immune apparatus to more specific and controlled manipulation of the immune system. IL-2 gives the opportunity to exert influence on the cellular immune system. Why LAK cells are able to lyse tumor cells and leave normal cells intact is not known. How LAK cells behave after reinfusion is not known; are they able to migrate to tumor sites? Can improvements be made in scheduling in order to decrease toxicity and to enhance efficacy? But first of all, the question arises whether the tremendous efforts required by adoptive transfer, in terms of toxicity, logistics, and money, are outweighed by the therapeutic results. For clinical practice inside the frontier of oncology, continuous infusion of IL-2 at an intermediate dose is a quite attractive option in finding a balance between efforts and results.