Reichenbach J, Jarisch A, Khan S, Homberg M, Bez C, Zielen S. Ann Allergy Asthma Immunol. 2002;89:498–502
Purpose of the Study.
To investigate the possible correlation between eosinophilic inflammation as measured by serum eosinophilic cationic protein levels (ECP) and bronchial hyperreactivity (BHR) as measured by methacholine inhalation challenge in infants with recurrent wheezing.
Seventy-two children, 6 to 31 months old (median: 15 months) were studied. All of the children had previously suffered from recurrent wheezing defined as >3 separate wheezing episodes in the past 12 months. Excluded were infants born prematurely or small for gestational age or known cardiopulmonary abnormalities. All patients with atopic dermatitis were excluded. None of the children were treated with inhaled corticosteroids or cromolyn for 4 weeks before the tests were performed. Bronchodilator treatment was stopped >12 hours before testing.
All children were sedated with chloral hydrate before lung function testing. Compliance of the respiratory system (CRS) and resistance of the respiratory system (RRS) were measured from the passive tidal expiratory flow volume curve obtained by standard single breath method before and after methacholine challenge. Only children with normal baseline flow volume loops, CRS, and RRS underwent methacholine provocation. Methacoline was inhaled during tidal breathing using a face mask with a leak-free seal. Starting dose consisted of 5 inhalations equivalent to 50 μg methacholine. Thereafter, the doses were increased by doubling the number of inhalations every 2 minutes until a positive reaction occurred defined as an increase of RRS by at least 50% or maximum dose of 900 μg methacholine was inhaled. Venous blood samples for ECP were performed after lung function testing. The subjects were divided into 3 groups based on serum ECP levels—low (<10 μg/L), medium (10–20 μg/L) and high (>20 μg/L).
Provocative methacholine concentrations at which an increase of RRS of at least 50% was measured, ranged from 30 to 976 μg. There was no significant correlation between serum ECP levels and BHR as measured by methacholine reactivity. Also, in all patients analyzed, there was no apparent relationship of BHR or high level of ECP with the levels of total or specific immunoglobulin E (IgE), peripheral blood eosinophils, family history of atopic disease, or exposure to cigarette smoking.
No significant correlation between serum ECP levels and bronchial reactivity was found in 72 children under 31 months of age with recurrent wheezing. These parameters may reflect 2 independent pathogenic mechanisms in the etiology of childhood asthma.