A single nasal allergen challenge increases induced sputum inflammatory markers in non-asthmatic subjects with seasonal allergic rhinitis: correlation with plasma interleukin-5.
BACKGROUND
Seasonal allergic rhinitis (SAR) is a risk factor for asthma in affected individuals. Nasal allergic inflammation enhances bone-marrow eosinophil production, mainly via IL-5, and rhinitis patients have increased airway inflammation during the pollen season.


OBJECTIVE
To assess the impact of nasal allergy on sputum inflammatory markers.


METHODS
In an open-labelled, randomized, placebo-controlled cross-over study with 16 non-asthmatic SAR patients (median age 25 years, 56% males), the effect of a single nasal allergen challenge performed out of season on induced sputum inflammatory parameters was evaluated. SAR patients were identified by history, skin-prick test and specific IgE. All patients had normal lung function/bronchial hyper-responsiveness out of season and a negative asthma/wheezing history. Sputum cells and supernatant levels of ECP, sICAM, IL-5 and IL-10, and plasma levels of IL-5 and ECP, were measured before and 24 h after nasal allergen challenge. After a washout period of at least 4 weeks, the procedure was repeated with placebo challenge (diluent).


RESULTS
Nasal allergen challenge led to an increase in sputum ECP (pre = 60 +/- 12, post = 212 +/- 63 micro g/L, P = 0.02 vs. placebo), and sICAM (4.8 +/- 2.7 to 6.5 +/- 2.9 ng/mL, P = 0.02 vs. placebo), whereas IL-10 decreased after provocation (44 +/- 11 to 29 +/- 6 pg/mL, P = 0.06 vs. placebo). Sputum IL-5 was undetectable in all patients. The absolute number of blood and sputum eosinophils did not change significantly after allergen or placebo challenge (P > 0.07, both comparisons). Plasma levels of IL-5 increased after allergen challenge (8.7 +/- 2.9 to 14.5 +/- 3.9 pg/mL, P = 0.001), and the increase in plasma IL-5 was positively correlated with the rise in sputum ECP in a subgroup of 'responders' (n = 12, r = 0.71, P = 0.01).


CONCLUSIONS
A single nasal allergen challenge in SAR patients increased markers of allergic inflammation in the lower respiratory tract, possibly via pronounced activation of inflammatory cells through circulating immediate-type reaction cytokines like IL-5. These findings may provide additional explanatory data for the high susceptibility of SAR patients to incident asthma.
Beeh
K M
KM
Pulmonary Department, Internal Medicine, University Hospital Mainz, Mainz, Germany. k.beeh@3-med.klinik.uni-mainz.de
Beier
J
J
Kornmann
O
O
Meier
C
C
Taeumer
T
T
Buhl
R
R
D000281:Administration, Intranasal; D000328:Adult; D000485:Allergens; D015415:Biomarkers / Q000032:analysis; D016085:Bronchoconstrictor Agents; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D015848:Interleukin-5 / Q000097:blood*; D008297:Male; D016210:Methacholine Chloride; D012044:Regression Analysis; D006255:Rhinitis, Allergic, Seasonal / Q000276:immunology*; D013183:Sputum / Q000276:immunology*
D000485:Allergens; D015415:Biomarkers; D016085:Bronchoconstrictor Agents; D015848:Interleukin-5; D016210:Methacholine Chloride