Variations of intracellular histamine basophil levels after treatment with ketotifen.

As reported in previous studies, ketotifen modifies the number of basophils in peripheral blood, most likely inhibiting their degranulation, which correlates with the lack of exercise-induced respiratory manifestations. In this study, we attempted to measure the approximate amount of intracellular histamine in patients with bronchial asthma sensitized to Dermatophagoides pteronyssinus when they were treated with ketotifen, and compare the values with those of an untreated group and a control group, in order to determine if ketotifen stabilizes the cellular membrane, with the subsequent increase of intracellular mediators. We found that untreated patients had 57% less histamine per basophil than the control group, while treated patients had only 17% less than the controls. This shows that ketotifen acts as a membrane stabilizer, thus inhibiting degranulation and increasing the amount of intracellular mediators.