Presence of human β-defensin-2 in oral lichen planus and its histamine releasing effect

Objective: To determine by immunohistochemical means the localization of human β-defensin-2, a peptide with antimicrobial activity, in oral lichen planus. The release of histamine from mast cells elicited by human β-defensin-2 was also investigated. Materials and Methods: Biopsy specimens of oral lichen planus, synthetic human β-defensin-2, human α-defensin-1, and mast cells isolated from Sprague Dawley rats were used. Tissue sections were embedded in paraffin and immunostained by the streptavidin-biotin-coupled peroxidase method. Isolated rat mast cells were injected with synthetic human β-defensin-2 and human α-defensin-1. Evans blue dye was injected into the tail vein of Sprague Dawley rats, followed by various doses of histamine, human β-defensin-2, human αdefensin-1, and saline. Results: Epithelial cells in lichen planus from the corneal layer to the spinous layer, were positively stained with anti-human β-defensin-2 antibody. Mast cells in subepithelial areas were also stained by anti-human β-defensin-2 antibody. Human β-defensin-2-induced histamine release from the isolated rat mast cells occurs in a dose-dependent manner. When human β-defensin-2 was injected into rat skin intradermally, the vascular permeability increased. These responses were completely abolished upon injection of the antihistamine drug diphenhydramine hydrochloride. Conclusion: Human β-defensin-2 and histamine may play an important role in the formation of oral lichen planus.