Pneumocystis carinii pneumonia (PCP) is accompanied by an acute inflammatory infiltration of the lung parenchyma. The cellular infiltrate is characterized by inflammatory cells including neutrophils, lymphocytes and macrophages. Furthermore, neutrophilia in bronchoalveolar lavage (BAL) fluid has been shown to confer a poor prognosis in PCP. We therefore investigated the potential of BAL fluid from 17 patients with PCP to induce neutrophil chemotaxis. BAL fluid from patients induced considerable neutrophil chemotactic activity compared to normal controls. Elevated levels of IL-8 were detected in patient samples as compared to controls. A specific anti-IL-8 antibody significantly reduced chemotactic activity of patient samples by more than 50%. In conclusion, IL-8 appears to be a significant participant of neutrophil chemotaxis in AIDS-associated PCP, and may participate in the recruitment of neutrophils to the lung during PCP.