Background Eoswinophil granule proteins may contribute to hyperresponsiveness in asthma.
Objective To measure eosinophil cationic protein (ECP) and eosinophil protein X (EPX) in sereum and bronchial lavage fluid from 20 asthmatics and 16 control subjects. To asses the effect on these eosinophil proteins of corticosteroid treatment of asthma. To determine ehether serum ECP and EPX measured weekly in a longitudina study for 10 weeks reflected changes in lung function.
Methods Eosinophil granule proteins were measured by radiommunoassy of bronchial wash (BW), bronchoalveolar lavage (BAL) serum.
Results Eosinophils were elevated in BAL(P<0.01), BW (P<0.01) and blood (P<0.01) from asthmatic compared with control subjects. Eosinophil cationic protein concentration was significantly elevated in BAL (P<0.05) and BW from asthmatics (P<0.01) and EPX was increased in BAL (P<0.05)and BW (P<0.01). These changes were also reflected in elevated serum ECP(P<0.01) and EPX (P<0.01)concentrations is asthmatic subjects. There was no significant difference between sujects receiving prednisolone and the placebo group, but there was a fall in ECP in BW (P<0.05) and serum (P<0.01) and in EPX in BW (P<0.01) and serum (P<0.01) within the group receiving prednisolone. In the longitudinal study there was only significant difference between ECP values associated with highest and lowest peak expiratory flow rate (PEFR) (P<0.05).
Conclusion These data confirm a role for cosinophil activation in the airway in asthma pathogenesis, and add some support to the hypothesis that corticosteroids may inhibit cosinophil activation in asthma.