Inhibitory effects of Quillaja saponin on IgE-mediated degranulation of rat basophilic leukemia RBL-2H3 Cells

The anti-allergic immunomodulatory effects of Quillaja saponin in antigen-stimulated rat basophilic leukemia cell line RBL-2H3 were investigated. Quillaja saponin exhibited a significant inhibitory activity using β-hexosaminidase and histamine release assays on anti-DNP-IgE-sensitized rat basophilic leukemia (RBL)-2H3 cells in a dose-dependent manner when tested in the range of 0.5–8.0 μg/mL. In addition, Quillaja saponin also suppressed mRNA expression of interleukins (IL)-4 and IL-6. In order to explore the antigen-allergy mechanisms of Quillaja saponin in mast cells, intracellular Ca2+ level and IgE receptor FcεRI mRNA expression were also determined. It was found that the intracellular Ca2+ level was also decreased with Quillaja saponin tested at various concentrations. Furthermore, real time-PCR results showed that mRNA expression of FcεRI α chain was significantly suppressed by Quillaja saponin, and not of the β and γ chains.

► Quillaja saponin could inhibit the secretion of β-hexosaminidase and histamine of RBL-2H3.
► Quillaja saponin could suppress the mRNA expression of IL-4 and IL-6.
► Quillaja saponin could decrease the intracellular Ca2+ level.
► Quillaja saponin could suppress the mRNA expression of FcεRI α chain, and not of the β and γ chain.