Propolis induces Ca signaling in immune cells.

Propolis possesses several immunological functions. We recently generated a conditional Ca biosensor yellow cameleon (YC3.60) transgenic mouse line and established a five-dimensional (5D) (x, y, z, time, and Ca signaling) system for intravital imaging of lymphoid tissues, including Peyer's patches (PPs). To assess the effects of propolis on immune cells, we analyzed Ca signaling and using CD11c-Cre/YC3.60 transgenic mice, in which CD11c dendritic cells (DCs) specifically express YC3.60. We found that propolis induced Ca signaling in DCs in the PPs. Intravital imaging of PPs also showed that an intraperitoneal injection of propolis augmented Ca signaling in CD11c cells, suggesting that propolis possesses immune-stimulating activity. Furthermore, CD11c cells in PPs in mice administrated propolis indicated an increase in Ca signaling. Our results indicate that propolis induces immunogenicity under physiological conditions.