Age-dependent relationship between bronchial hyperresponsiveness to methacholine and total serum IgE level in asthmatic children.

BACKGROUND: A relationship between nonspecific bronchial hyperresponsiveness and allergic airway inflammation has been reported in children and in adults with asthma, but the relationship in infants with asthma is still unclear.

OBJECTIVE: To evaluate the relationship between bronchial hyperresponsiveness and total serum IgE level throughout childhood. Bronchial reactivity to methacholine from the age of 1 to 16 years was studied by methacholine inhalation challenge using transcutaneous oxygen pressure (tcPO2) monitoring.

METHODS: Two hundred one asthmatic children (boys:girls = 132:69; 7.3+/-4.0 years of age, mean +/- SD) were enrolled in this study. The tcPO2 was measured using a tcPO2 monitor. Serial doses of methacholine were doubled until a 10% decrease in tcPO2 from the baseline was reached. The cumulative dose of methacholine at the inflection point of tcPO2 was considered to represent the bronchial reactivity to methacholine.

RESULTS: There was no relationship between the cumulative dose of methacholine at the inflection point of tcPO2 and total serum IgE level in the group of children aged 1 to 4 years (P = 0.212), but significant correlations were found in the groups aged 5 to 10 years and 11 to 16 years (P = 0.044 and P = 0.014, respectively).

CONCLUSIONS: We conclude that there is an age-dependent relationship between bronchial reactivity to methacholine and the total serum IgE level and that inhaled allergens, which were more common allergens in older children, may have some effects on the degree of bronchial reactivity to methacholine in children with asthma.