Inhibitory effects of Schefflera leucantha extract on production of allergic mediators by Langerhans cells and mast cells.

BACKGROUND Schefflera leucantha Viguier is used as a traditional medicine in Thailand and China to relieve chronic cough and asthma. However, little is known about its anti-allergic effects. OBJECTIVE This study was designed to investigate the effects of S leucantha ethanol extract (SLEE) on chemokine production by epidermal Langerhans cells (LCs) stimulated with peptidoglycan (PEG) from Staphylococcus aureus and histamine release from mast cells. METHODS LCs were purified from murine epidermal cells using the panning method with anti-IA(d) monoclonal antibody. Chemokine production by LCs was investigated by reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA). Mast cells for histamine release assay were induced by long-term culture of mouse spleen cells. Histamine release from these mast cells was measured by a competitive ELISA. RESULTS Production of the eosinophil chemoattractant CCL5 and the type 2 T helper (TH2)-associated chemokine CCL17 from PEG-stimulated LCs was significantly inhibited by SLEE. Furthermore, SLEE significantly decreased the release of histamine from mast cells by IgE-mediated degranulation. CONCLUSION These results suggest that S leucantha may offer a new therapeutic approach for the control of atopic dermatitis associated with S aureus colonization through inhibition of the production of allergic mediators.