Eosinophil cationic protein (ECP) in saliva: a new marker of disease activity in bronchial asthma.

Eosinophil cells play a crucial role in the pathogenesis of asthma, and concentration of eosinophil cationic protein (ECP) in serum has been used to monitor activity of the disease. Our aim was to determine the feasibility and usefulness of measuring ECP in saliva and to use it as a marker of the disease. Thirty-eight patients with asthma and 16 healthy volunteers were included in this study. Repeatability of measurements of ECP in saliva was acceptable [intra-class correlation coefficients (Ri) = 0.74 and coefficients of repeatability (CR) = 0.37 in five healthy subjects]. Levels of ECP in saliva were higher in asthmatics than in volunteers (P < 0.01). There was a significant inverse association between a surrogate variable reflecting disease activity (i.e. change over a few weeks in dose of inhaled corticosteroid required by a change in clinical status of asthma) and a change over the same time period in salivary ECP in 19 patients with stable asthma (r = -0.64, P = 0.02). Our findings indicate that levels of salivary ECP are elevated in patients with asthma and associated with presumed activity of disease as recorded by alteration of taken dose of inhaled corticosteroid.