Aberrant cutaneous weal and flare responses in chronic urticaria.

This study examined cutaneous mast cell behaviour in 14 patients with chronic urticaria but no dermographism and 11 healthy controls, by measuring cutaneous weal and flare reactions evoked in response to intradermal challenge injections of 0.1 ml isotonic saline, histamine (20 micrograms), codeine phosphate (10 micrograms) and compound 48/80 (10 micrograms). Five minutes after each injection, the area of the resulting weal and flare was calculated by computer-aided planimetry. The process was repeated at 15, 30 and 45 min following the injection. In patients, saline flares were significantly larger than those of the volunteers at 15, 30 and 45 min (p < 0.05). However, histamine and codeine flare areas were significantly smaller in the patients when compared to the controls at 15, 30 and 45 min (p < 0.05). Compound 48/80 produced smaller reactions in the patients without reaching statistical significance.