Serum eosinophil peroxidase (EPO) levels in asthmatic patients

Eosinophil granular proteins are a useful eosinophilic activation marker in asthmatic patients. In this study, the eosinophil peroxidase (EPO) levels were assessed in different stages of bronchial asthma, in 123 patients suffering from asthma, classified as mild (n =49), moderate (n = 49), and severe (n = 25), according to the International Consensus Report of Diagnosis and Treatment of Asthma, as well as in 27 healthy controls, with the aim of evaluating the importance of this protein as a severity marker in bronchial asthma, and its possible correlation with parameters such as anamnesis, respiratory function tests, and peripheral blood eosinophil count, and also with some allergologic diagnostic tests, both in vivo and in vitro. The geometric mean serum level of EPO was 9.3 +/- 11.3 ng/ml (median +/- SD) in controls, 28 +/- 37.8 ng/ml in the asthmatic patients. Depending on the asthma severity, the EPO levels were 25 +/- 30.5; 29 +/- 37.1, and 41 +/- 47.3 ng/ml in mild, moderate, and severe asthmatics, respectively, being the significant differences between the group of patients with mild and severe asthma (P < 0.001). The number of eosinophils (eos) in peripheral blood was 157 +/- 20 eos/mm3 in the controls, 334/35 eos/mm3 in mild asthmatics, 510 +/- 87 eos/mm3 in moderate asthmatics, and 658 +/- 72 eos/mm3 in severe asthmatics, with significant differences between all groups (from P < 0.05 to P < 0.001). Both the serum levels of EPO and the number of eosinophils were greater in patients with active asthma patients with inactive asthma (P < 0.001). Significant negative correlations (P < 0.001) were found between serum levels of EPO and FEV1 (rs = 0.30), MEF25-75 (rs = -0.33) and MEF50 (rs = -0.34), and a good positive correlation (rs = 0.80, P < 0.001) was found between EPO levels and the number of eosinophils in peripheral blood. We also found a significant positive correlation between eosinophil number and clinical score (rs = 0.54, P < 0.001) and between EPO levels and the mentioned score (rs = 0.46, P < 0.001).