An outbreak of rapidly progressive obstructive lung disease in Taiwan was noted in some patients regularly ingesting the vegetable Sauropus androgynus because of its perceived weight reducing properties. Bronchoalveolar lavage (BAL) prior to administration of medication was performed in two women who had regularly ingested this vegetable and had developed obstructive ventilatory defects. Both patients showed a significant increase in neutrophils and, to a lesser extent, of eosinophils in the lavage fluid as compared to two unrelated controls. Interleukin (IL)-1 beta, IL-2, IL-5, IL-10, interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha in cells recovered from BAL fluid were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). Augmented expression of the IL-10 gene was detected in only two patients who had regularly ingested S. androgynus. Our results suggest that altered cytokine expression and infiltration of eosinophils and neutrophils may be involved in the pathology of obstructive lung disease caused by regular ingestion of S. androgynus.