DO SPUTUM EOSINOPHILS AND ECP RELATE TO THE SEVERITY OF ASTHMA

There is much evidence that eosinophils play an important role in bron chial epithelial damage in asthma by releasing cationic proteins, Howe ver, the extent to which eosinophil inflammation relates to indices of asthma severity in chronic stable asthma is still a matter of debate, We studied 46 clinically stable patients with mild to severe chronic asthma (forced expiratory volume in one second (FEV1) 50-126% of predi cted value), The clinical severity of asthma was graded from 1 to 4 ac cording to the Aas scoring system, Twelve normal subjects were also st udied as controls, Induction of sputum was performed by hypertonic sal ine to determine differential cell count, and eosinophil cationic prot ein (ECP) by the so-called ''plug technique'', The concentration of EC P was measured by a fluoroimmunoassay, Bronchial hyperresponsiveness w as recorded by inhaling progressive concentrations of histamine, and t he concentration that caused a 20% decrease in FEV1 (PC20) was calcula ted. Sputum eosinophils (range 0-61%), sputum ECP (range 24-10,800 mu g.L-1) and serum ECP (range 4-61 mu g.L-1) were significantly greater in asthmatics than in normal subjects, and distinguished the most seve re group with the highest Aas score from the others, Sputum eosinophil s and sputum ECP were strongly related to each other, The relationship s between sputum or serum ECP and PC20 (range 0.016-7.5 mg.mL(-1)), an d between sputum ECP and FEV1 were found to be weak, In conclusion, sp utum outcomes of eosinophil activation and serum eosinophilic cationic protein appear to be useful indicators of disease, They do not accura tely reflect current clinical or functional indices of asthma severity in chronic stable patients, and might therefore provide complementary data disease monitoring.