Lipid peroxidation by alveolar macrophages challenged with Cryptococcus neoformans, Candida albicans or Aspergillus fumigatus.

Increased formation of oxygen radicals has previously been shown for alveolar macrophages (AM) challenged with Cryptococcus neoformans cells opsonized with fresh serum or polyclonal immunoglobulin G. AM show similar responses to Candida albicans or Aspergillus fumigatus. Oxygen radicals are capable of damaging various macromolecules, including lipids. In the present study, lipid peroxidation (LPO) caused by AM incubated with the fungi was examined in the presence and absence of lung surfactant. The level of malonaldehyde was used as an indicator of LPO. AM damage was examined by electron microscopy (EM), by trypan blue exclusion and by counting the AM loss from culture dish to supernatant. Stimulation of AM by each fungus increased cellular LPO but did not affect AM viability. A slight surfactant LPO induced by AM alone was shown with significantly increased values after addition of each fungus. EM studies showed that dense lipid droplets, presumably consisting of oxidized lipids, were ingested in high amounts together with C. neoformans cells that had been opsonized in fresh serum, and in low amounts in combination with C. albicans. These processes were accompanied by increased numbers of AM in the supernatants. LPO and detachment of AM were counteracted by vitamin E. In the lungs, AM exposed to one of these fungal pathogens might promote peroxidation of surfactant lipids.