Serum levels of eosinophil cationic protein in allergic diseases and natural allergen exposure

Abstract

BACKGROUND: Eosinophil cationic protein (ECP) is a cytotoxic preformed mediator stored in eosinophil granules and released under various in vitro and in vivo conditions. OBJECTIVE: This study was carried out to evaluate the clinical value of ECP as a marker of allergic inflammation. METHODS: ECP was measured by a competitive radioimmunoassay in serum samples from 265 patients and 45 matched control subjects and related to the type of allergic disease (asthma, rhinitis, conjunctivitis) and to the type of allergic sensitization. RESULTS: All the patient groups studied showed significantly higher levels of serum ECP than control groups (p < 0.001). The type of sensitization was shown to be the only variable influencing ECP serum levels. In fact, subjects sensitized to perennial allergens had significantly higher ECP values than subjects with seasonal allergy (p < 0.001), whereas in patients with seasonal allergy ECP levels were significantly increased only during the pollen season. Differences in ECP values between various allergic diseases or age groups were only due to a nonhomogeneous distribution of the type of sensitization or to time of sera collection. CONCLUSIONS: Results obtained indicate that persistent natural exposure to a sensitizing allergen is responsible for a measurable increase in serum ECP levels in patients with allergy. (J ALLERGY CLIN IMMUNOL 1996;97:1350-5.)