Eosinophil Cationic Protein - Clinical Significance

Clinical Significance

Eosinophil granulocytes appear in large numbers in inflammation sites and in response to certain parasitic infections. These cytoplasmic granulocytes contain positively charged proteins that characterize the cells. ECP is one of the four highly basic proteins that enter the surrounding tissues when activated eosinophil degranulate. Although circulating ECP levels can vary widely among patients, some studies show that serum ECP measurements are useful in monitoring many active inflammatory diseases. ECP concentrations in plasma and other body fluids increase during inflammatory reactions are marked by activated eosinophils.

Serum ECP levels has also been thought as a useful, objective measurement for asthma severity. Increased ECP levels correspond to symptom onset. In seasonal asthmatic patients, ECP measurement reflected changes in disease activity throughout the year.

There are several mechanisms that can be combined to generate an asthma attack, including specific IgE antibodies, activated inflammatory cells, neurogenic mechanisms, hyperresponsiveness and individual hormonal imbalances. Allergic reactions in the lung typically have two phases, in which the late phase typically occur several hours after exposure, in which eosinophils accumulate in the bronchus and resease granule proteins that causes bronchial irritability. ECP is also toxic to neurons, some epithelial cell lines and isolated myocardinal cells. This could be a reason for itching disorders of the skin in patients.

Serum ECP concentrations has also been linked to atopic dermatitis (AD) activity. ECP correlates with the symptoms (lichenification, Sleep deprivation, erythema, papules, pruritus and excoriations) for AD and also correlates with the total clinical score.

Serum ECP measurement for assessing asthma severity, monitoring therapy and indicating severity of certain inflammatory skin conditions present an advantage over subjective clinical measures that are prone to inconsistencies due to broad variability of individual investigator and patient assessments, especially in young children.

The normal reference range for blood tests for eosinophil cationic protein is between 2.3 and 16 µg/L.