A lucigenin-enhanced chemiluminescence (CL) assay was used to assess alveolar macrophage (AM) and blood monocyte (BM) function in patients with lung cancer (LC). Ten patients with LC (7-SCLC, 3-NSCLC) and ten matched controls underwent bronchoalveolar lavage, and AMs were subjected to CL with and without stimulation with latex beads. Peak CL was recorded as counts per minute (CPM)/10(3) cells/min. BM activity was similarly assessed in 17 LC patients (13-SCLC) and 17 matched controls. Peak activity of both unstimulated and latex stimulated AMs in the LC group was higher than controls. Similarly, BM activity was enhanced in LC patients compared with controls. There was no correlation between AM CL responses and disease extent, but BM function at diagnosis correlated with subsequent response to cytotoxic chemotherapy. Results indicate both local and systemic activation of the monocyte/macrophage system in LC even in patients with limited disease.