Release of histamine and leukotriene C₄ in immediate allergic wheal reaction as measured with the microdialysis technique

Abstract Other mediators as well as histamine can contribute to the allergic wheal reaction. In this study, the microdialysis technique was used to monitor the release of histamine, leukotriene C₄ (LTC₄) and prostaglandin D₂ (PGD₂) in prick-test wheal reactions induced by cow dander allergen. Of 31 atopic subjects, 25 showed detectable histamine release that correlated significantly with the number of tryptase-positive mast cells and serum cow-specific IgE but not with the wheal size. Detectable LTC₄ release was shown by 16 of 18 subjects, but PGD₂ release was shown by only 7 of 17 subjects, and neither mediator was associated with tryptase-positive mast cells, IgE levels or wheal size. An inverse association between histamine release and LTC₄ release in these 18 subjects was found rather than a direct correlation. With advancing age of the subject histamine release (n = 31) tended to decrease, although insignificantly, but LTC₄ release (n = 18) and sensitivity to histamine prick increased significantly, which seemed to parallel the changes in the wheal size induced by cow allergen. In conclusion, the results showed that the release of histamine, LTC₄ or PGD₂ alone cannot explain the extent of the wheal reaction. In addition, the amount of histamine released was not related to the amount of LTC₄ released, but rather an inverse association existed between these mediators.