Serum eosinophil cationic protein in asthma of farmers

There is need for relevant markers of bronchial inflammation in epidemiologic studies of asthma. Serum eosinophil cationic protein (ECP) is a marker of eosinophil inflammation and asthma activity. We have studied serum ECP in atopic farmers with current asthma, in non-atopic asthmatics and in non-asthmatic, non-atopic controls.

In a cross-sectional study of a representative sample of 8,482 farmers in Norway, asthma was recorded using a self-administered questionnaire; spirometry and serum sampling were performed on all of them. Atopy was screened with Phadiatop and RAST analyses to the mites Lepidoglyphus destructor and Tyrophagus putrescentiae in all asthma cases and controls. All the identified atopics had additional RAST analyses on a set of allergens. Serum ECP was tested in 60 persons with current asthma and atopy (mean 16.2, 95% CI 13.2-19.3), 127 non-atopic asthmatics (mean 9.1, 95% CI 8.0-10.2) and 39 non-atopic controls (mean 5.5, 95% CI 4.0 7.0). ECP levels in atopic asthmatics were associated with number of positive allergens and reduction of FEVI values. Moreover, the ECP levels were elevated with allergy to swine, cow, D. pteronyssinus, L. destructor, A. siro, T. putrescentiae, timothy grass and the cereal grains: wheat, oat, barley and rye.

Serum ECP seems feasible as an indicator of inflammatory activity in epidemiological studies of current allergic asthma, and may help to indicate the importance of specific allergens. Although the ECP values were significantly more elevated in atopic than in non-atopic asthma, elevated serum ECP was not specific for atopic asthma.