Examination of cellular proteins has become part of common clinical practice in all medical disciplines. The development of modem biotechnological methods and procedures, a more sensitive method of protein estimation in biological material and certainly also the reduced price of these specialized examinations made their extensive use in clinical practice possible. One of these biomarkers - i.e. products of cells participating in the pathological or physiological reaction of the organism - is also the eosinophil cationic protein - ECP. It is a produkt of activated eosinophil leucocytes, which are one of the main effector cells of allergic inflammations. The article summarizes the problem of ECP from the aspect of practical application focused on bronchial asthma in childhood and with regard to more recently published data.

        Key words: asthma bronchiale, eosinophil cationic protein (ECP), atopy