In this study we have analyzed various phagocytic functions of human neutrophils exposed to either biochemically well defined porcine surfactant (Curosurf) or a phospholipid preparation. Adherence, random migration and chemotactic response to zymosan activated serum and formyl-methionyl-leucyl-phenylalanine were normal in surfactant treated neutrophils; surfactant was not a chemotactic stimulus. In contrast, phagocytosis of S. aureus by neutrophils exposed to surfactant (100 micrograms/ml) or phospholipids (100 micrograms/ml) was impaired (surfactant: t30 49.5 +/- 9.0%, t60 65.0 +/- 8.0%; phospholipids: t30 66.3 +/- 12.6%, t60 78.0 +/- 7.8%; controls: t30 78.1 +/- 8.9%, t60 90.1 +/- 6.2%; p less than 0.001 at t30, t60 for surfactant, p less than 0.05 at t60 for phospholipids). Due to the smaller number of S. aureus ingested, bactericidal activity of surfactant or phospholipid treated neutrophils was slightly reduced when compared to controls (surfactant t30 p less than 0.05, surfactant t60 p less than 0.001, phospholipids t60 p less than 0.05). Surfactant or phospholipids had no bactericidal activity. Uptake of candida was identical in surfactant or phospholipid treated neutrophils with untreated controls; the same was true with the number of candida per cell ingested. Phagocytosis-associated chemiluminescence and production of superoxide anion by neutrophils of either source in response to phorbol myristate acetate and opsonized zymosan was also identical.