Inhibition of antigen-induced degranulation and IL-4 production from RBL-2H3 cells by Lavandula hybrida and L. angustifolia extracts

Allergic diseases are considered to be multifactorial inflammatory diseases that present a serious health problem worldwide while their prevalence have continuously increased during the past few decades. They are results of type I hypersensitivity mediated through the effects of antigen-specific IgE which binds to mast cells and, on subsequent cross-linking by allergen reexposure, causes cell degranulation with the release of preformed mediators in the early-phase as well as the production of cytokines in the late-phase. The aim of our study was to investigate the antiallergic activities of cultivated Lavandula hybrida Rev. and L. angustifolia P. Mill. using the rat basophilic leukaemia cell line (RBL-2H3), a well-characterised in vitro model of mast cells. The ethanolic extracts of flowers of L. hybrida (LHE) and L. angustifolia (LAE) were found to significantly inhibit release of β-hexosaminidase, the marker of antigen-IgE-mediated degranulation in RBL-2H3 cells, showing similar activities (IC₅₀=37µg/mL and IC₅₀=42µg/mL, respectively). Furthermore, using the enzyme-linked immunosorbent assay (ELISA), we established that LHE and LAE inhibit antigen-induced production of anti-inflammatory cytokine IL-4 (IC₅₀=60µg/mL and IC₅₀=45µg/mL, respectively). Among ten investigated principal bioactive compounds, luteolin, apigenin and ursolic acid were found to be the most potent inhibitors of degranulation as well as cytokine production. In conclusion, the tested extracts showed antiallergic effects acting on the both phases of type I reaction. Therefore, our results suggest a possible therapeutic application of Lavandula species in allergy and allergy-related diseases.