Histamine release from rat mast cells induced by human α-defensin-1 present in jaw cyst fluid

Objective: To investigate the release of histamine from rat mast cells elicited by human α-defensin-1 contained in jaw cyst fluid. Patients and Methods: Human α-defensin-1 was purified by reversed-phase high-performance liquid chromatography from human jaw cyst fluid, and the mast cells were collected from the peritoneal cavities of rats. Results: Histamine release was induced in isolated rat mast cells by both extracted and synthetic human α-defensin-1. Changes in vascular permeability induced by human α-defensin-1 were also estimated by the passive skin test in rats. Extracted and synthetic human α-defensin-1 induced histamine release from isolated rat mast cells in a dose-dependent manner over a concentration range of 1 to 15 μg/mL; the histamine release induced by the extracted and synthetic human α-defensin-1 (15 μg/mL) was 39.4 ± 2.3 and 37.6 ± 1.8%, respectively. When human α-defensin-1 was injected into rat skin intradermally, the vascular permeability increased. This response occurred with as little as 0.1 μg of human α-defensin-1, and a strong response was observed with 0.5 and 1.0 μg. These responses were completely abolished upon injection with 1μg of the antihistamine drug diphenhydramine hydrochloride. Conclusion: Human α-defensin-1 in human jaw cyst fluid can act as an inducer of histamine release from mast cells both in vivo and in vitro.