Reactive oxygen intermediate (roi) generation was investigated in phagocytes of 39 patients undergoing pulmonary resection for lung cancer and 39 paired healthy controls. Generation of roi in monocytes and neutrophils was monitored using 2',7'-dichlorofluorescin diacetate. Activation associated with hydrophobic interactions was probed by analysis of phagocyte roi activation by arachidonic acid and gamma-linolenic acid. Patient roi was measured pre-operatively and 2 and 7 days post-operatively. Elevated (P < 0.01) roi production was detected in neutrophils of lung cancer patients. Surgery was associated with an increase (P < 0.05-P < 0.01) in phagocyte roi at 2 and 7 days post-op. Phagocyte roi was stimulated by arachidonic acid and gamma-linolenic acid (1-40 microM) both pre- and post-operatively. Differences in arachidonic acid and gamma-linolenic acid stimulation between patient and control and pre- and post-op patient phagocytes suggest arachidonic acid involvement in phagocyte activation during reactive responses to lung carcinoma and surgery.