Leukotriene C4 and histamine in early allergic reaction in the nose

Abstract

We have examined the measurements of LTC₄ and histamine in nasal lavage fluids and blown secretions as a possible model of the early mediator events during nasal allergy. A nasal challenge with grass pollen extract was undertaken on two separate occasions in 20 patients with a history of seasonal rhinitis and a positive immediate skin test to grass pollen. A 2 ml nasal lavage was performed before allergen challenge, and blown secretion collected separately 15 min after the provocation, followed by a final 2 ml nasal lavage. The dilution of nasal secretion by the lavage fluid was determined using ^99mTc‐labelled albumin as an exogenous marker added to the fluid. The amounts of admixture in the nasal lavages did not correlate to the concentrations of LTC₄ and histamine, indicating that the variable amounts of nasal secretion in nasal lavage do not constitute a confounding variable for measurements of LTC₄ and histamine. In the pre‐challenge lavages, the median concentrations, of LTC₄ and histamine were 1.7 and 52 nmol/1 respectively. Following allergen challenge neither LTC₄ nor histamine measured in nasal lavage showed any significant change from pre‐challenge baseline values. However, measurements of both mediators in the blown secretion showed a significantly higher concentration than in the pre‐ or post‐challenge lavage samples, compatible with transitory release during the acute allergic reaction. However, it seems doubtful whether measurements of LTC₄ or histamine can be compared between blown secretion and nasal lavage fluid, even if the dilution factor is disregarded. While allergen provocation of the nasal mucosa releases inflammatory mediators locally, uncontrolled variables confound their measurement in the nasal lavage fluids to an extent which limits the application of this model to study details of mediator release during nasal allergy.