Predictors of early‐ and late‐phase reactions to bronchial allergen challenge

Abstract

The influence of inhaled steroids and predictive factors on the response to bronchial allergen challenge (BCA) was evaluated in 80 asthmatics allergic to Dermatophagoides pteronyssinus (Der p). All underwent BCA with Der p and measurement of early (EAR) and late asthmatic reaction (LAR). The cumulative dose of allergen producing 20% fall in FEV1 in the EAR (PD20) was calculated. Bronchial histamine provocation, conjunctival provocation test (CPT), and skin prick test with Der p extract were performed. Specific IgE to Der p in serum (RAST), blood eosinophil (EOS) count, serum eosinophil cationic protein, and eosinophil protein X were measured. Thirty patients (38%) were treated with inhaled steroids. All patients had at least a 20% fall in FEV1 in EAR. Some 42% of nonsteroid- and 33% of steroid-treated patients had LAR with fall in peak flow of at least 20%. For patients not treated with steroid, 35% of variation in PD20 was explained by RAST and histamine reactivity, and 53% of variation of observed PD20 could be predicted. The baseline FEV1, EOS, and EAR explained 28% of variation in LAR, and 28% of variation in observed LAR could be predicted. For patients treated with steroids, 38% of variation in PD20 was explained by EOS and histamine reactivity, and only 18% of variation of observed PD20 could be predicted. For patients treated with steroids, it was impossible to predict LAR. We conclude that to achieve a quantitative estimation of allergen-specific EAR and LAR, BCA cannot be replaced by the tests used in this study. Treatment with inhaled steroids modifies the response to BCA, making quantitative prediction of EAR less accurate and prediction of the magnitude of LAR impossible.

Bronchial allergen challenges in children – safety and predictors

“…It is known that the responsiveness to histamine or methacholine correlates with a positive response during bronchial allergen challenges. The correlation between the PC 20 histamine and the PD 20 allergen was r = 0.43, p < 0.01 , and it has been shown that methacholine challenge correlates with the PC 20 allergen ( r = 0.25, p = 0.0015) and with the PD 15 allergen ( r = 0.25) . We found a correlation similar to the results of Haugaard et al.…”

Predictors of Late Asthmatic Response

“…Our results confirm and extend previous studies in which the development of a LAR in allergic asthmatic subjects has been found to be associated with increased bronchial responsiveness to histamine or methacholine (11,12,21) and with the early asthmatic response (9,10). Although Machado and Stalenheim did not find a correlation between LAR and baseline bronchial reactivity to methacholine (8), this study included smokers and subjects with borderline hyperresponsiveness (6 of 24 subjects had methacholine PC 20 higher than 8 mg/ml).…”

“…This is time-consuming, labor-intensive, and expensive. Previous studies that have examined predictors of LAR in asthmatic subjects have not studied large numbers of subjects and have yielded conflicting results about predictors (6)(7)(8)(9)(10)(11)(12)(13) so that no baseline asthma variable is used widely to identify subjects likely to have a LAR.…”

Anterior Hypothalamic Lesions Inhibit Antigen-Induced Airway Eosinophilia in Rats

“…However, mast cell activation has been proposed to be associated with the LAR [22]. In addition, some, but not all, studies demonstrated that a lower value for methacholine PC 20 at baseline and a greater fall in FEV 1 during an early asthmatic response predict the development of the LAR [23,24]. Therefore, this mechanism can not be completely neglected when considering the mechanism of AHA-lesion-associated inhibition of LAR.…”