Allergen-specific nasal challenge: response kinetics of clinical and inflammatory events to rechallenge.
Allergen-specific nasal challenge is a valid and reliable tool for studying the pathophysiological mechanisms involved in allergic inflammation. Nasal challenge induces an immediate clinical response in allergic subjects and a concomitant appearance of an inflammatory infiltrate. The mucosal inflammation may persist up to 48-72 h after allergen exposure. If the subjects are rechallenged within this period the response is more pronounced: the so-defined priming effect. The aim of the study was to evaluate the effects of the nasal rechallenge, performed at different time intervals: 3 days, 1, 2 and 4 weeks after the first challenge. Forty allergic subjects underwent two nasal challenges: at baseline and after the periods mentioned above (10/group). Symptoms and inflammatory cells (eosinophils and neutrophils recovered by nasal brushing) were assessed. The 3-day-interval group showed a hyperreactive response (priming effect), the 1- and 4-week-interval groups showed a response similar to baseline, and the 2-week-interval group showed a hyporeactive response ('tolerogenic effect'). The last phenomenon may be due to a possible immunologic response similar to that achievable during local specific immunotherapy. The present results further elucidate the kinetics of allergen-driven inflammatory events and highlight the importance of the time period chosen for rechallenge. The latter fact may be of primary importance in clinical trials involving specific challenge.
Ciprandi
G
G
Department of Internal Medicine, University of Genoa, Italy.
Ricca
V
V
Landi
M
M
Passalacqua
G
G
Bagnasco
M
M
Canonica
G W
GW
D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000009:adverse effects*; D004804:Eosinophils / Q000276:immunology; D005260:Female; D006801:Humans; D007700:Kinetics; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D009297:Nasal Mucosa / Q000166:cytology / Q000276:immunology; D009299:Nasal Provocation Tests; D009504:Neutrophils / Q000276:immunology; D006109:Poaceae; D011058:Pollen / Q000009:adverse effects*; D006255:Rhinitis, Allergic, Seasonal / Q000209:etiology / Q000276:immunology*
D000485:Allergens