Influence of total IgE and seasonal increase of eosinophil cationic protein on bronchial hyperreactivity in asthmatic grass-sensitized farmers

Background: This study correlates biomarkers of atopy (serum total and spec ific IgE) and inflammation (serum eosinophil cationic protein) with bronchi al hyperreactivity assessed after the complete end of pollination, in a gro up of farmers suffering from grass-allergic asthma. Methods: A total of 28 asthmatic farmers, with allergy to grass pollen, rep orting persistent asthma symptoms after grass pollination, were enrolled. A n accurate allergologic screening excluded other sensitizations. Analysis o f total and grass-specific IgE and eosinophil cationic protein was carried out before (March) and during (May) the following spring. After the complet e end of pollination, bronchial hyperreactivity was assessed. Results: Symptoms (cough, wheezing) persisted during the autumn for a mean period of 41 days (range 13-69). Total IgE was moderately high and grass-sp ecific IgE ranged from 9.25 to 41.12 kU/1 without significant differences b efore and during spring. On the contrary, serum ECP levels significantly in creased during the pollination period. PD20 methacholine evaluated after th e end of grass pollination was negatively significantly correlated with lev els of total IgE (r= -0.73; P < 0.01) and the increase (from March to May) of serum ECP (r= -0.75; P < 0.01). However, PD20 methacholine did not corre late with grass-specific IgE and serum ECP absolute values of both March an d May. A positive correlation was found between number of postseasonal days with symptoms and both spring increase of serum ECP (r = 0.75; P = 0.04) a nd levels of total IgE (r = 0.76; P < 0.01). The number of postseasonal day s with symptoms inversely correlated with postseason PD20 methacholine (r = -0.76; P < 0.01). Conclusions: The study demonstrates that in grass-sensitized farmers with a sthmatic symptoms persisting for several weeks after grass pollination has ceased, the degree of airways hyperreactivity and the duration of postseaso nal symptoms are directly related to the spring increase of ECP levels, as well as to the level of total IgE in serum. This allows us to identify two candidate biomarkers for the risk of developing prolonged asthma symptoms, and for the effective monitoring of anti-inflammatory treatment and allerge n-specific immunotherapy.