A single reaction-diffusion equation for the multifarious eruptions of urticaria
Fig 1
Histamine dynamics and expanding speed of wheals in experiments vs wheals observed in patients with chronic spontaneous urticaria.
(A) The process of urticarial development. Dermal mast cells are stimulated and degranulate, releasing mediators including histamine (a, b). Released histamine acts on vascular endothelial cells and sensory neurons to induce the formation of intercellular gaps (c) and the release of neuropeptides which activate mast cells in the vicinity (d). The blood plasma exudates through the gap and wheals develop (e). (B) The upper left panel shows photographic images of a wheal induced by the intradermal injection of histamine and the lower left panel shows wheals observed in a patient with chronic spontaneous urticaria (CSU) over a time course. Right panels show the evolution of wheals in terms of their size, showing that wheals in CSU expand much slower than those induced by a bolus injection of histamine. (C) Comparison of the radial expansion velocities of wheals that developed in patients with CSU and of those induced by a bolus intradermal injection of histamine. The maximum radial expanding velocity of wheals induced by intradermal injections of histamine was calculated as the average velocity during the initial 15 minutes after the injection, and that in CSU was calculated as the fastest of the average velocity during the observational time of two adjacent points. The radial expanding velocity of histamine-induced wheals at the indicated concentrations was at least 7 times greater than that of wheals developed in CSU.