Peripheral blood mononuclear cells obtained from 24 primary lung cancer patients were stimulated with anti-CD3 monoclonal antibody (alpha CD3MoAb) followed by culture with recombinant interleukin-2. The optimal concentration of alpha CD3MoAb for stimulation was 50 ng/ml in the liquid phase, and the sensitization culture was commenced at a cellular concentration of 1 x 10(6)/ml. Patients entered into this study were 14 cases of adenoca rcinoma, 7 of squamous cell carcinoma, and 3 of small cell carcinoma. After 4-6 days of stimulation with alpha CD3MoAb followed by culture with RIL-2 for 5-7 days, the cellular expansion was 3.7 folds (mean). Surface marker analysis of the cells revealed significant increments of CD3+, CD8+, HLA-DR+, and IL-2R+ cells after sensitization culture. In 2 cases, fresh autologous tumor cells could be obtained from surgical specimens. Effector cells generated in those 2 cases did not show significant cytotoxic activity against autologous tumor cells in 4 hr 51Cr release assay. In 5 cases, cytotoxicity against established lung cancer cell lines, STC-1 and L0301, were analyzed. In all cases, effector cells showed significant cytolytic activity against both targets. The sensitization culture utilizing alpha CD3MoAb was easy to perform and feasible for the majority of patients, and it is considered that utilization of this culture system would be worth while for adoptive immunotherapy in primary lung cancer patients.