Study objective: To examine the baseline factors
influencing the occurrence and magnitude of immediate- and late-phase
responses in asthmatic patients after an allergen-induced bronchial
provocation test (A-BPT).
analysis in a homogenous group of 31 mild, Dermatophagoides
pteronyssinus-allergic patients with asthma.
Setting: Allergy Department, Hospital Virgen del Camino,
Interventions and measurements:
Patients completed an asthma symptom questionnaire and underwent skin
tests, sputum induction, and methacholine bronchial provocation test.
The A-BPT was performed on a separate day. Sputum cell profile and
eosinophil cationic protein (ECP), tryptase, albumin, and interleukin-5
levels were quantified in the entire sputum supernatant. Assays
were done for eosinophils in blood, and/or ECP, and total and specific
IgE levels in serum. Exposure to D pteronyssinus major
allergens (Der p1 and Der 2) was measured by an assay based on
Results: A-BPT findings were
positive in all patients, and late-phase responses were detected in
29%. Late responders were exposed to higher levels of Der p1
(p = 0.028), had greater levels of ECP (p = 0.007) and albumin
(p = 0.019) in sputum, and showed a trend toward higher lymphocyte
numbers (p = 0.053) in sputum than isolated early responders. The
allergen-induced provocative dose that induced a fall in
FEV1 values ≥ 20% from the postdiluent values correlated
with bronchial hyperresponsiveness (r = 0.36). The
late-phase response magnitude correlated with Der p1 exposure
(r = 0.49) and showed a trend toward correlation with
sputum ECP levels (r = 0.38).
Conclusion: Factors involved in the development of
allergen-induced immediate- and late-phase responses are different.
Allergen natural exposure might prime the infiltration of the airway by
activated inflammatory cells enhancing the appearance and the severity
of late-phase responses.