Changes in non‐specific nasal reactivity and eosinophil influx and activation after allergen challenge

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Abstract
It has been suggested that the eosinophilic granulocyte plays a crucial role in the genesis of increase reactivity of the airways. In order to characterize changes in non-specific reactivity inthe upper airways following a nasal allergen challenge further 16 sujects with strictly seasonal allergic rhinitis were studied. They were challenged with allergen outside the relevant pollen season and monitored at intervals for a period of 24 hr for nasal symptoms, changs in nasal reactivity, eosinophil influx, and activation, and markers of inflammation. The same challenge sequence without an initial allergen challenge was used as a control. A symptom score technique was used to record nasal symptoms and methacholine challenges were used to monitor changes in non-specific reactivity. A nasal lavage was made prior to each methacholine challenge to monitor the influx of cells, specifically eosinophils, and to determine changes in the levels of eosinophil cationic protein (ECP) and TAME-esterase activity. Cells from the mucosal surface were also collected with a Rhinobrush prior to the allergen challenge as well as at the 24-hr follow up. The allergen challenge induced a five-fold increase in non-specific nasal reactivity, as measured by the methacholine challenges, at the 2-hr follow up from 0.051 .+-. 0.012 (mean .+-. s.e.m.) to 0.255 .+-. 0.062 (P < 0.01) and a significant increase was also noted at all observation points, whereas no increase could be observed in the control setting. With a similar timing the allergen challenge also induced an increase in the proportion of eosinophils on the mucosal surface from an initial 0.8 .+-. 0.4% to 6.2 .+-. 2.1% of the cells as early as 2 hr s later (P < 0.05). A significant correlation was found between the levels of ECP and eosinophils in the lavage fluid (R = 0.64, P < 0.001) and between the levels of ERCP and TAME esterase (r = 0.43, P < 0.01). No correlations were, however, disclosed between the increases in non-speciifc nasal reactivity and the number of eosinophils (regardless of cell-harvesting technique) or ECP levels at any of the observed time points. It is therefore suggested that the allergen-induced change in non-specific nasal reactivity is a complex phenomenon rather than just the recruitment and activation of eosinophilic granulocytes in the nasal cavity.