Local Cellular and Humoral Responses to Antigenic and Distilled Water Challenge in Subjects with Allergic Rhinitis

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Abstract
We studied nasal responses to allergen, saline, and distilled water aerosol in 7 subjects with allergic rhinitis to determine whether they caused a similar release of mediators and influx of inflammatory cells into the nasal lumen. The subjects were challenged first with allergen and then with aerosols of distilled water and of normal saline in random order on separate days. We measured nasal airway resistance (Rn) by posterior rhinomanometry, measured the concentrations of protein, histamine, leukotrienes (LT) B4, C4, and D4, and platelet-activating factor (PAF-acether) and performed total and differential cell counts in nasal lavage fluid obtained before and after each challenge. Allergen challenge provoked a 2-fold or greater increase in nasal airway resistance in all subjects (mean increase = 12.2-fold). This response was associated with significant increases in protein, histamine, LTB4, and sulfidopeptide leukotrienes. 2-lyso-PAF-acether increased significantly, indicating activation of phospholipase A2, but PAF-acether was detected in only one subject. The total cell count increased from 55 .+-. 44 .times. 103/ml to 200 .+-. 168 .times. 103/ml; polymorphonuclear neutrophils increased from 11 .+-. 22 .times. 103/ml to 108 .+-. 96 .times. 103/ml, and eosinophils increased from 1.3 .+-. 1.8 .times. 103/ml to 10.6 .+-. 15.3 .times. 103/ml (p < 0.05). Saline insufflation provoked insignificant changes in mean Rn, in the levels of protein and all inflammatory mediators, and in the number and types of cells in nasal lavage fluid. Distilled water insufflation also provoked an insignificant increase in mean Rn, but there was a 14-fold increase in one subject. For the group as a whole, nasal lavage fluid protein increased significantly, but inflammatory mediators and cell number and distribution did not. In the responsive subject, however, the biochemical and cellular response to distilled water resembled both his own and the group''s response to allergen. Our results suggest that while distilled water aerosol can provoke the release of the same mediators as those released after allergen challenge, the presence of the mechanisms of immediate hypersensitivity in the nose is not sufficient to induce responsiveness to distilled water aerosol.