Differences in interleukin-1β release-inducing activity of Candida albicans toward dendritic cells and macrophages

Objective: The purpose of this study is to elucidate differences in the mechanism of the IL-1 beta release-inducing activity of Candida albicans toward dendritic cells and macrophages because IL-1 beta is one of the proinflammatory cytokines which is crucial in host defense against candidiasis. Design: Two C. albicans strains were used in this study. One strain is uridine-auxotrophic (CAI4) that needs uridine to grow and form hyphae, and another is a strain without any specific auxotrophy (pACT1-GFP), which forms hyphae naturally by culturing with serum components. Murine macrophage and dendritic cell lines were primed with LPS and then stimulated with C. albicans CAI4 or pACT1-GFP. Results: Both strains of C. albicans induced IL-1 beta release from dendritic cells, and C. albicans pACT1-GFP induced IL-1 beta release but CAI4 induced little amounts in macrophages. These differences were suggested to be due to the difference in the amount of extracellular ATP released in the cell culture supernatants induced by C. albicans CAI4 or pACT1-GFP. For induction of IL-1 beta release from both macrophages and dendritic cells by C. albicans, direct contacts of the microbes with cells were required. In addition, macrophages required morphological change of C. albicans from yeast to hyphae for induction of IL-1 beta release, whereas dendritic cells did not require it. Dead C. albicans could induce IL-1 beta release from dendritic cells, but could not from macrophages. Conclusions: There are different mechanisms by which C. albicans induces IL-1 beta release from dendritic cells and macrophages.