In vitro effect of lung surfactant on alveolar macrophage defence mechanisms against Cryptococcus neoformans

The effects of a modified natural porcine surfactant (Curosurf) on phagocyt osis and killing of Cryptococcus neoformans by alveolar macrophages and on the production of superoxide anions were investigated in vitro. Attachment and ingestion were evaluated separately by a fluorescent quenching techniqu e. The nitroblue tetrazolium reduction test was used as an indirect measure ment of superoxide anion production. Killing was assessed by a colony-formi ng assay. Surfactant induced increased ingestion of C. neoformans, unopsoni zed as well as opsonized with fresh serum or anticryptococcal polyclonal Ig G. Surfactant had, however, no effect on the attachment or killing of unops onized or opsonized C. neoformans by the alveolar macrophages. In addition, the enhancement of the oxidative metabolism of the macrophages after stimu lation with opsonized yeast was impaired, although the killing was not affe cted. This study indicates that in vitro Curosurf can influence the alveola r macrophage defence against C. neoformans by enhancing its ingestion and b y interacting with the superoxide anions release from alveolar macrophages stimulated with fresh serum or anticryptococcal polyclonal IgG opsonized ye ast cells.