Background. Bronchial asthma is a chronic inflammatory disease of the respiratory tract where variety of cells plays a role, particularly mast cells, eosinophils (Eo), and T lymphocytes. At present, there is no clear-cut clinical or laboratory parameter to monitor the activity of this disease. Our study was designed to examine and compare serum eosinophilic cationic protein (S-ECP) levels, plasma ET-1 (P-ET) levels and percentage of eosinophils with CD44 (EoCD44) in paediatric asthmatic patients. Methods and Results. In our study, a group of 97 atopic children with persisting mild asthma, had a detailed analysis of their personal history. In addition, S-ECP, P-ET, EoCD44, eosinophil blood count (Eo) and serum levels of IgE(S-IgE) in peripheral blood were determined. Subsequently, children were treated with montelukast (singular), a leukotriene receptor antagonist for a period of three weeks (montelukast tablets in a dose of 5 mg once a day). A second S-ECP, P-ET, EoCD44 were determined in the interval of 3 months from the first collection. In 97 asthmatic children a correlation between P-ET and EoCD44 (p=0.002; r= –0.5) were found. Conclusions. Our follow-up study surprisingly confirmed a correlation between P-ET and EoCD44. The lower percentage of EoCD44 in peripheral blood in asthmatic children is due to Eo inflammation activity and attests the massive Eo invasion into the airways. The determination of combination - S-ECP, P-ET, EoCD44 – provides an indirect evidence of the multiple features of Eo inflammation.

        Key words: bronchial asthma, eosinohpilic inflammation, endotheline, eosinophil cationic protein, % eosinophils with CD44.