Immunomodulation Effects of Schizonepeta tenuifolia Briq. on the IgE-Induced Allergic Model of RBL-2H3 Cells

Schizonepeta tenuifolia (ST) Briq. is a traditional herbal medicine commonly used to treat allergic skin diseases, where the inflammation process is closely related to symptom severity. This study aimed to explore the immunomodulatory effect of ST by using immunoglobulin E- (IgE-) stimulated RBL-2H3 cell cultures, a common cell line for studying mast cell degranulation and inflammatory cytokine release in vitro. After stimulating the RBL-2H3 cells with IgE, ST at concentrations of 10, 50, or 100 μg/mL was added to the cell cultures. Cell viability, inflammatory cytokines (IL-6, IL-13, IL-4, TNF-α, and IFN-γ), anti-inflammatory cytokine IL-10, and degranulation ability were examined 48 and 72 hours after administration of ST. The markers of inflammation and allergic reaction, IFN-γ, TNF-α, IL-4, and IL-6, were suppressed, especially after treatment with 100 μg/mL ST. However, the anti-inflammation marker IL-10 was also suppressed by ST. Trend analysis showed that a higher ST concentration was associated with lower IFN-γ and TNF-α levels. Moreover, degranulation of RBL-2H3 cells was assessed by measuring the release of β-hexosaminidase, which was suppressed by ST at 10 μg/mL. This study showed an immunomodulatory effect of ST at the cellular level and suggests the role of ST in treating allergic diseases.