In this study we have analyzed various phagocytic functions and tumor necrosis factor (TNF) secretion of human monocytes exposed to either a biochemically well-defined porcine surfactant or a purified phospholipid preparation. Adherence, random migration, and chemotactic response to zymosan activated serum and formyl-methionyl-leucyl-phenylalanine were normal in surfactant-treated monocytes; surfactant was not a chemotactic stimulus. In contrast, phagocytosis of Staphylococcus aureus by monocytes exposed to surfactant (100 micrograms/mL) or phospholipids (100 micrograms/mL) was slightly impaired [surfactant: at 30 min (t30) 48.5 +/- 11%, t60 73.3 +/- 10.1%; phospholipids; t30 47.3 +/- 2.5%, t60 68.0 +/- 6.6%; controls: t30 66.6 +/- 9.9%, t60 81.0 +/- 6.6%, p less than 0.05 at t30 for both, 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 monocytes was slightly reduced when compared with controls. Surfactant or phospholipids had no bactericidal activity. Uptake of Candida albicans was identical in surfactant- or phospholipid-treated monocytes and untreated controls; the same was true for the number of Candida organisms ingested per cell. Phagocytosis-associated chemiluminescence and production of superoxide anion by monocytes of either source in response to phorbol myristate acetate and opsonized zymosan were also unaffected.(ABSTRACT TRUNCATED AT 250 WORDS)