Differentiation of extracellular from ingested Candida albicans blastospores in phagocytosis tests by staining with fluorescein-labelled concanavalin A.

In phagocytosis tests with human polymorphonuclear (PMN) cells, extracellular blastospores of Candida albicans could be distinguished microscopically from ingested blastospores mor easily than with methods used previously by staining phagocyte monolayers with fluorescent-labelled concanavalin A. This stain reacted with the cell wall mannan of extracellular blastospores but seemed unable to reach that of the ingested blastospores. This technique both improves determination of phagocytic indices and checks that extracellular blastospores have been washed away before assessment of intracellular survival and growth.