Adoptive immunotherapy of human pancreatic cancer with lymphokine-activated killer cells and interleukin-2 in a nude mouse model. A pancreatic cancer cell line was grown in orthotopic and heterotopic positions in young Swiss/NIH nude mice, which were tested with adoptive immunotherapy. Mice were injected with 1 x 10(7) human cancer cells in the subcutaneous tissue and duodenal lobe of the pancreas. The mice were randomly divided into four groups: group IA (LAK + IL-2) (N = 25) received 2 X 10(7) human lymphokine-activated killer (LAK) cells from normal donors by tail vein injection followed by 10,000 units of human recombinant interleukin-2 (IL-2) given intraperitoneally every 12 hours for 28 days; group IB (IL-2) (N = 27) was given the same dose of IL-2 alone; group IC (RPMI-1640) (N = 18) received a placebo consisting of 1 ml of RPMI-1640 intraperitoneally every 12 hours; and group ID (LAK) (N = 14) received 2 X 10(7) LAK cells but no IL-2. Toxicity was significantly higher in group IB, with a mortality rate of 45.5% (10/22 animals) versus a 0% mortality (0/25) in group IA. None of the group IA or IB animals died of pancreatic cancer during the experiment. The animals that did not receive IL-2 died before 28 days in 14.2% of group IC and in 16.7% of group ID. The area under the growth curve of subcutaneous tumors during the course of treatment and the pancreatic tumor weight at the end of treatment were compared in each group. Subcutaneous tumors had a reduced rate of growth in group IA animals compared to all the other treatments. Pancreatic tumor growth was slowed in group IA. The animals treated with IL-2 alone (group IB) showed some slowing of tumor growth that was intermediate between group IA, group IC, and group ID. A similar experiment was done with irradiated (375 rad) mice. Nine nude mice with tumors were treated with LAK + IL-2 (group IIA), eight received IL-2 alone (group IIB), and seven received placebo (group IIC). The antitumor effect of IL-2 alone was not present in the irradiated mice. A highly significant difference persisted between group IIA and all other groups. There was no difference in the histologic characteristics of tumors in control mice and in mice with inhibited tumor growth treated with IL-2 or IL-2 and human LAK cells. These results show that adoptive immunotherapy with human LAK cells and human recombinant IL-2 is effective against human pancreatic cancer growing in nude mice. This effect is independent from antitumor activity from IL-2 administrations alone. 