The mechanism of ketotifen-induced histamine release from human peripheral leucocytes

Ketotifen-induced histamine release from human leucocytes is independent of extracellular calcium and does not require metabolic energy. Furthermore, histamine release is accompanied by a loss of cellular cytoplasmic contents. This suggests that the mechanism of ketotifen-induced histamine release at high concentrations is non-specific and is similar to that of clemastine, a typical H1 antagonist.