Eosinophil activity in bronchial asthma.

Eosinophil cationic proteins (ECP), eosinophil protein X (EPX), eosinophil peroxidase (EPO), eosinophil-derived neurotoxin (EDN), and the major basic protein (MBP) have been identified as potent cytotoxic secretory proteins in degranulated eosinophils. Studies of these proteins have clearly indicated a role for eosinophil-derived proteins in inflammatory diseases, including asthmatic inflammation. It has been shown that higher levels of ECP in asthmatics were concomitant with severity of the disease and related to efficacy of treatment of asthma. Proper handling of blood serum for measurement of eosinophil and neutrophil markers including myeloperoxidase (MPO) is essential. Moreover, the time factor in ECP measurement is an important variable because ECP levels differ in chronic stable asthma, during acute exacerbations of asthma, and after allergen challenge. Simultaneous measurements of ECP and MPO may prove to be useful in determining various causes of asthma exacerbations, helping to discriminate between allergic etiologies wherein ECP levels may increase versus infectious etiologies wherein MPO levels may increase. Monitoring the efficacy of anti-inflammatory therapies such as corticosteroids may be enhanced by serial determinations of ECP levels in the blood.