Ultrastructural features of phagocytosis and intracellular killing of Candida albicans by mouse polymorphonuclear phagocyte monolayers

Phagocyte monolayers provided a simple method of following ultrastructural events associated with phagocytosis and intracellular killing of Candida albicans. Preformed monolayers of mouse polymorphonuclear (PMN) phagocytes attached to glass coverslips were incubated with blastospore phase C. albicans and then examined by scanning and transmission electron microscopy. Scanning electron microscopy revealed phagocytosis of C. albicans by mouse phagocytes. Ingestion of the organism was facilitated by the production of lamellipodia by the phagocytes. Transmission electron microscopy revealed complete phagocytosis of C. albicans and the fusion of lysosomal granules with loose and tight phagosomes. Ingested C. albicans remained structurally intact after 2 hr incubation in blastospore-free medium. However, cytoplasmic alterations were clearly evident, with a patchy loss of electron density. Alterations of the blastospore cell wall were also observed, with complete disruption of the plasma membrane but the wall remaining morphologically intact.