Int Public Health Journal 2009;1(2) ISSN: 1947-4989 Editor: Joav Merrick,pp. © 2009 Nova Science Publishers, Inc. Eosinophil cationic protein in pediatric asthma Eugenia Panagiotopoulou, MD 1 , Michael B. Anthracopoulos, MD, PhD, FAAP 1 and Kostas N. Priftis, MD, PhD 2 1 Respiratory Unit, Department of Pediatrics, University Hospital of Patras, Rio-Patras 2 Department of Allergy-Pneumonology, Penteli Children’s Hospital, P Penteli, Athens, Greece  Correspondence: Michael Anthracopoulos MD, PhD, FAAP, Department of Pediatrics, University of Patras School of Medicine, Rio 265 04, Greece. Tel: +30-2610- 999544; Fax: +30-2610-994533; E-mail: manthra@otenet.gr Abstract Eosinophil granulocytes (eosinophils) are white blood cells that develop from bone marrow precursor cells. Their major morphological characteristic is eosinophilic granules within the cytoplasm, which are divided into specific and small granules. Four cationic proteins have been recognized within the eosinophil specific granules that include eosinophil cationic protein (ECP). It displays a variety of biological activities, most notably cytotoxicity that is due to its ability to make pores in cell membranes. ECP exerts this action on parasites, viruses, bacteria, tumor cells, and even respiratory epithelial cells. Other biological functions include stimulation of mucus production in the airway, interaction with the coagulation and complement systems, and immunomodulation. The role of ECP as a marker of eosinophil activity has been investigated in a variety of body fluids and diseases, particularly in wheezing children. The role of ECP has been investigated in acute viral bronchiolitis of infants and preschool wheezing in reference to both pathogenesis and prognosis of the disease. There is evidence that ECP can be used in asthma to evaluate severity, patient compliance to anti-asthma treatment, and to step-down inhaled corticosteroid dosage in stabilized patients. Further studies are required in order to elucidate its role as a diagnostic and prognostic tool in pediatric asthma. Keywords: Eosinophil cationic protein, asthma, bronchiolitis, children, wheezing. Introduction Eosinophil granulocytes (eosinophils) are white blood cells that develop from bone marrow precursor cells and differentiate under the control of various growth and colony-stimulating factors. After a five day maturation period, eosinophils circulate in the peripheral blood. Only a small fraction of eosinophils remains in the bloodstream, while most mature cells immigrate to the tissues, preferably those exposed to the external environment such as the respiratory and