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Flare responses of atopic eczema patients analysed with true colour images
Objective And Design:
Attenuated flare responses of atopic eczema (AE) patients to histamine are well documented, but their origin is still unknown.
Subjects And Methods:
Here we studied the development of erythema after histamine iontophoresis in 12 AE patients and 12 healthy volunteers by means of a RGB-camera for recording true colour images.
Treatment:
10 mg cetirizine or placebo was administered orally 3 h before the experiment in a crossover design.
Results:
The flare reaction was found to develop after termination of histamine iontophoresis in two phases: a first phase lasting 1-2 min in which the flare increased by about 10 mm2/s and a second phase lasting another 10-15 min characterized by a slower growth in the range of 1 mm2/s.
Conclusions:
Flare size was diminished in AE patients, mainly due to a slower or absent growth in the second phase. Oral application of the H1-antagonist cetirizine (Zyrtec) reduced the flare reaction in both groups of volunteers significantly, indicating that the reaction is dependent on the activation of chemosensitive nerve fibres via H1-receptors.