The authors examined peripheral blood mononuclear cells from 45 patients with bronchogenic carcinoma to determine natural killer (NK) and lymphokine-activated killer (LAK) activity after in vitro incubation with media alone or media plus interferon gamma (IFN, 200 U/ml) and/or interleukin-2 (IL-2, 100 U/ml). Our results show that lymphocytes from patients with bronchogenic carcinoma can acquire LAK activity, but the level of activity acquired was significantly lower compared with lymphocytes from 25 control subjects when IL-2 cultures were supplemented with 10% autologous human serum (AHS) (15.6% +/- 2.1% specific release versus 26.0% +/- 2.9% specific release, P = 0.004). The LAK activity, defined as cytotoxicity of an NK-resistant cell line, of the patients' lymphocytes was augmented when cells were cultured with both IL-2 and IFN compared with IL-2 alone (P = 0.0001, paired t-test). Control subjects were unchanged (P = 0.09). There was no significant difference between groups of patients with different histologic types of tumor or different stages of disease. The NK activity, defined as killing of NK-sensitive K-562 target cells, of the patients' lymphocytes was not significantly different from that of the controls' lymphocytes (42.8% +/- 3.0% specific release versus 49.3% +/- 3.3% specific release, P = 0.16). These studies indicate the feasibility of IL-2 and IFN therapy in patients with bronchogenic carcinoma.