A xenograft model of local adoptive immunotherapy would be useful in evaluating the therapeutic effects both cytokines with and without added effector cells have on human head and neck tumors implanted into nude mice. Human squamous cell carcinomas of the head and neck lend themselves to local intervention and, since conventional radio- and/or chemotherapy often fail to arrest tumor growth, new therapeutic modalities, including immunotherapy, must be considered and local immunotherapy may have the advantage of minimal side effects. In the present study the ability of local adoptive immunotherapy with human lymphokine-activated killer cells (LAKc) and recombinant interleukin-2 (IL-2) to inhibit the growth of established squamous cell carcinoma of the head and neck was evaluated in nude mice. The model was established by subcutaneous injections of in vitro maintained tumor cells into the flank splenectomized animals pretreated with cyclophosphamide and anti-asialo GM1. The line used was tumorigenic in 95% of the nude mice and neither metastasized nor killed the animals. The local daily administration of IL-2 to the tumor site for two weeks resulted in a significant inhibition of tumor growth. Complete inhibition of tumor growth was achieved with three times weekly injections of 5 to 10 x 10(6) LAKc delivered to the tumor site and 1000 U of IL-2 administered locally every day for two weeks. The data obtained indicate that local adoptive immunotherapy with IL-2 and an adequate dose of LAKc may be effective in preventing the in vivo growth of established squamous cell carcinomas of the head and neck.