ECP in Asthma
Research Use for Disease and Therapy Assessment

In industrialized countries, about 5 percent of the population suffers from asthma, and the incidence continues to rise. Asthma costs millions of dollars per year in hospitalization, medication and lost work days; it can be fatal in serious cases. Several components combine to generate an asthma attack. Specific IgE antibodies, activated inflammatory cells, neurogenic mechanisms, hyperresponsiveness and individual hormonal imbalances can contribute to this response in varying degrees. Allergic reactions in the lung typically have two phases. In the early phase, occurring within minutes of allergen exposure, mast cells release histamine, tryptase and leukotrienes. During the late phase, typically occurring several hours after exposure, eosinophils accumulate in the bronchus and release their granule proteins, causing bronchial irritability.

The goal in treating asthma is to maintain a relatively symptom-free condition and, above all, to avoid debilitating asthma attacks. Serum ECP levels may provide a useful, objective measure of asthma severity. Physician evaluations of asthma severity and medication requirements often rely on subjective indices reported by patients, including daily symptom scores and use of inhaled asthma medication. These measures are prone to inconsistencies due to variations in investigator and patient assessments. They can also be difficult to obtain, especially in young children, and most of them imperfectly reflect physiologic alterations involved with asthma. Patient symptoms may subside despite the presence of residual disease in the form of reduced lung capacity and bronchial hyperreactivity. Patients with decreased pulmonary function who remain asymptomatic may later experience shortness of breath caused by severely restricted lung capacity.

Studies point to ECP's clinical utility as an indicator of asthma severity and as a monitor for asthma therapy. Several studies report high individual and group correlation between ECP levels and other indicators of clinical asthma, such as peak expiratory flow (PEF) measurements, airway responsiveness, number of inhaler puffs needed and patient symptom scores.^1,2 Circulating ECP levels increase in patients after they have been exposed to specific allergens, demonstrating the involvement of ECP in active inflammatory conditions. Atopic serum samples often have higher ECP levels than nonatopic control samples, even when the circulating-eosinophil count remains within the normal range.³ Increased ECP levels correspond to symptom onset; in seasonal asthmatic patients, ECP measurements reflected changes in disease activity throughout the year.^1,3 Roquet et al. reported significant correlation between ECP levels and bronchial hyperreactivity in mildly asthmatic patients.⁴ Tomassini et al. showed that serum ECP concentrations exceeded normal control levels in both IgE-mediated and non-IgE-mediated atopic conditions.³

ECP has shown value for assessing asthma severity and monitoring therapy. For more information on ECP, a technical report entitled "Role of ECP in Monitoring Inflammatory Conditions" is available from DPC. Please contact your local DPC representative or National Distributor for the technical report (catalog number ZB181-A), or for information on DPC's IMMULITE® ECP* assay.

*Available outside the US.

References

1. D'Amato G, Liccardi G, Russo M, Saggese M, D'Amato M. Measurement of serum levels of eosinophil cationic protein to monitor patients with seasonal respiratory allergy induced by Parietaria pollen (treated and untreated with specific immunotherapy). Allergy 1996;51:245-50.

2.Vatrella A, Ponticiello A, Parrella R, Romano L, Zofra S, DiLeva A, et al. Serum eosinophil cationic protein (ECP) as a marker of disease activity and treatment efficacy in seasonal asthma. Allergy 1996;51:547-55.

3. Tomassini M, Magrini L, De Petrillo G, Adriani E, Bonini S, Balsano F, et al. Serum levels of eosinophil cationic protein in allergic diseases and natural allergen exposure. J Allergy Clin Immunol 1996;97:1350-5.

4. Roquet A, Hallden G, Ihre E, Hed J, Zetterstrom O. Eosinophil activity markers in peripheral blood have high predictive value for bronchial hyperreactivity in patients with suspected mild asthma. Allergy 1996;51:482-8.