Predictors of response to bronchial allergen challenge in 5- to 6-year-old atopic children.

BACKGROUND: The relationship between atopy and bronchial allergy in young children is not completely understood. OBJECTIVE: To examine the association between response to bronchial allergen challenge, immune markers of atopy and other clinical characteristics in 5- to 6-year-old children. METHODS: Children with positive skin test (SPT) to aeroallergen, together with a proportion of SPT negative children (as controls), were recruited from a birth cohort of 198 children at high risk of developing atopic disease and underwent allergen challenge. RESULTS: Thirty-seven children (26 atopic and 11 SPT negative), median age 74.5 months, were challenged: 31 with house dust mite and six with grass allergen. Only atopic children responded to challenge: n = 12/26 (46%). Wheal size [odds ratio (OR) 2.5 (1.2-5.3), P = 0.01], allergen-specific immunoglobulin E (IgE) [OR 3.4 (1.23-9.61), P = 0.02], total IgE [OR 8.6 (1.1-68.7), P = 0.04], current wheeze [OR 12 (1.7-81.7), P = 0.006] and persistent eczema [OR 11.0 (1.7-68.3), P = 0.006] emerged as the strongest independent predictors of response to allergen challenge. Prediction of response to allergen challenge was significantly improved when immune markers of atopy, and in particular wheal size, were combined with clinical characteristics. CONCLUSION: The relationship between atopy and bronchial allergy is quantitative at this age. There may be potential to create more powerful indicators of the presence of respiratory allergy in young children when immunological markers of atopy are considered quantitatively and when combined with clinical history of coexistent allergic disease.

Value of eosinophil cationic protein and tryptase levels in bronchoalveolar lavage fluid for predicting lung function impairment in anaesthetised, asthmatic children.

Bronchial hyperactivity, a key feature of active asthma in children, is a risk factor for respiratory adverse events in the peri-operative period. The presence of activated eosinophils in the lungs and mast cell degranulation can contribute to bronchial hyperreactivity. Eosinophil cationic protein is released by activated eosinophils and tryptase reflects mast cell degranulation. This study focused on the relationship of respiratory mechanics, eosinophil cationic protein and tryptase levels in bronchoalveolar lavage fluid in asthmatic and healthy children under general anaesthesia. We measured eosinophil cationic protein and tryptase levels in bronchoalveolar lavage fluid from 21 asthmatic and 21 healthy children following induction of general anaesthesia. Respiratory system resistance and dynamic compliance were measured during mechanical ventilation. Eosinophil cationic protein was more common in bronchoalveolar lavage fluid from asthmatics (12/21) than from controls (4/21, p = 0.01) and was present at higher levels (p = 0.002). Tryptase was also more common in the asthmatics (8/21 vs 1/21, p = 0.01). Respiratory resistance was significantly higher in asthmatic children with detectable eosinophil cationic protein levels than in those with undetectable eosinophil cationic protein levels (p = 0.019). Furthermore, 50% of the asthmatics with detectable eosinophil cationic protein exhibited bronchospasm after sampling their bronchoalveolar lavage fluid. These findings suggested that high levels of eosinophil cationic protein in the bronchoalveolar lavage fluid are associated with irritable airways, presumably secondary to airway inflammation, and this might be a useful marker for respiratory adverse events in the peri-operative period.