Phagocytosis and intracellular killing of Candida albicans blastoconidia by neutrophils and macrophages: a comparison of different microbiological test systems.

Polymorphonuclear neutrophils (PMN) and mononuclear phagocytes represent an important first line and effector function in the control of Candida infections. Their relative contribution to host defence is frequently assessed by means of microbiological assays. However, reported results are divergent and might well be associated with study design-related issues. In the present study, we compared frequently used microbiological candidacidal assays, with the purpose of determining the most adequate method for assessment of phagocytosis and intracellular killing. We concluded that microbiological assays using yeast-phagocyte suspensions are inappropriate for the assessment of intracellular killing of Candida blastoconidia by murine macrophages, due to adherence or clumping of cells. In contrast, an adherent monolayer of phagocytes can be applied as a single microbiological assay to independently study the process of phagocytosis and intracellular killing, by exudate peritoneal macrophages as well as exudate peritoneal PMN.