Original Articles: Mechanisms of Allergic and Immune DiseasesMagnitude of late asthmatic response to allergen in relation to baseline and allergen-induced sputum eosinophilia in mild asthmatic patients
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INTRODUCTION
Early asthmatic response (EAR) and late asthmatic response (LAR) are characteristic features of bronchial allergen challenge in appropriately sensitized individuals,1 but it is not clear which determinants affect the development and the magnitude of LAR. Only approximately 50% of patients with EAR have LAR,2 and its development is related to certain determinants, especially hyperresponsiveness to direct stimuli and allergic sensitivity. Both these findings can predict the presence of LAR.3, 4, 5
Patients
Thirty-eight patients (12 females and 26 males; mean age, 21.2 years [range, 15-37 years]) with mild asthma were selected. All the patients were examined during a stable phase of disease, without respiratory tract infections and asthma exacerbations in the previous 4 weeks. In a preliminary evaluation, each patient had positive skin prick test reactions to at least 1 of the following: Dermatophagoides pteronyssinus, Dermatophagoides farinae, Graminaceae, and Parietaria officinalis (mean wheal
RESULTS
Allergen inhalation caused EAR and LAR in all the patients. The mean values of functional and biological findings measured before and after allergen challenge are reported in Table 2. As expected, methacholine PD20FEV1 significantly reduced during LAR compared with baseline values (0.052 vs 0.353 μg; P < .001). Sputum samples were successfully obtained from all the patients except 1 at baseline and 2 at 24 hours after allergen challenge testing. In the baseline evaluation, the median (range)
DISCUSSION
The main finding of the present study is that baseline and allergen-induced sputum eosinophilia are significantly associated with the magnitude of LAR in a group of patients with EAR plus LAR after allergen challenge. The hypothesis that the baseline level of airway inflammation can be a determinant of the development or magnitude of LAR has been previously investigated. Only 2 studies4, 5 examined the relationship between allergen-induced airway responses and baseline sputum eosinophilia. Both
ACKNOWLEDGMENTS
We thank Elisa Masino and Mariella De Santis for performing functional measurements in the laboratory.
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Disclosures: Authors have nothing to disclose.