Different effectiveness of fungal pathogen-associated molecular patterns (PAMPs) in activating rat peritoneal mast cells.

Mast cells (MCs) are the first immune cell type that can contact with the external environment, where they may rapidly sense the presence of pathogens. These cells are directly involved in innate defense through their ability to pathogen destruction by several mechanisms and the pattern recognition receptors (PRRs) they express. Several studies have focused on the aspects of MC responses to bacterial and viral pathogens or their specific components and the role of those cells in antibacterial or antiviral defense mechanisms. However, to date, the knowledge of the influence of various fungi-derived molecules on MC activity is primarily based on limited data. Thus, this study aims to compare the effect of the major fungi cell wall-associated antigens, i.e., two β-(1,3)-glucans: zymosan - β-(1,3)-glucan containing mannan and chitin, and curdlan - purified linear model β-(1,3)-glucan as well as mannan on peritoneal MC activity. In particular, the potency of various fungal cell wall components to induce MC migration, degranulation, and generation and/or release of de novo-synthesized mediators/cytokines/chemokines was analyzed. The most striking result to emerge from the data is that MC activation differs depending on the fungal stimuli. Our study outlines that components of the inner layer of the fungi cell wall - β-glucans, i.e., zymosan and curdlan, are more potent stimulators of MC activity compared to mannan. On this note, the data described here may provide a foundation for further studying the role of MC in antifungal immunity and be helpful for a better understanding of host-pathogenic fungi interactions.