NASAL AIRWAY CHANGES ASSESSED BY ACOUSTIC RHINOMETRY AND MEDIATOR RELEASE DURING IMMEDIATE AND LATE REACTIONS TO ALLERGEN CHALLENGE

Background: We have found that acoustic rhinometry is a reliable means of assessing nasal airway caliber changes during the immediate reacti on to nasal allergen challenge of sensitive subjects. Comparison of su ch changes with symptoms and patterns of mediator release could help i n the understanding of mechanisms of immediate and late-phase reaction s after allergen challenge and their clinical relevance. Methods: Nasa l minimal cross-sectional area (MCA) was assessed sequentially for 6 h ours after two blinded challenges in random order with pollen antigens and buffer diluent in five sensitive human subjects. Comparisons were made with: (1) symptom scores; (2) olfaction changes; and (3) nasal s ecretion levels of histamine, tryptase, leukotriene C-4, serum albumin (a marker of vascular permeability), lactoferrin (a marker of local g landular secretion), and inflammatory cells in nasal scrapings. Result s: In four of five subjects there was a significantly greater decrease in MCA after antigen challenge than after diluent challenge, correlat ing with the degree of subjective nasal congestion. In two of these fo ur subjects there was a prominent second late-phase decrease in MCA at 3 to 5 hours, whereas the MCA was persistently decreased in an additi onal subject with accompanying subjective congestion. No significant d ecrease in olfactory acuity occurred. Levels were significantly higher in nasal secretions obtained after antigen challenge than in those ob tained after buffer challenge with histamine (9 +/- 2.7 ng/ml vs 1.2 /- 0.5 ng/ml; p = 0.04); tryptase (95 +/- 83 ng/ml vs 3 +/- 0.9 ng/ml; p = 0.02), leukotriene C-4 (5293 +/- 1385 ng/ml vs 578 +/- 183 ng/ml; p = 0.02), and albumin (123 +/- 9 ng/ml vs 19 +/- 1.6 ng/ml; p = 0.00 5) but not with lactoferrin (4.6 +/- 1.2 ng/ml vs 4.1 +/- 28 ng/ml; p = not significant). Granulocyte exudation was seen after antigen chall enge but not after buffer diluent challenge. However, there was not a precise correlation between decreases in MCA with changes iii levels o f these mediators in individual subjects. Conclusions: Acoustic rhinom etry can quantitatively assess congestion during immediate and late-ph ase reactions after nasal challenge without significant correlation to the degree of individual inflammatory events assessed.