EosinophilCationic

Eosinophil Cationic Protein (ECP), also known as eosinophil cationic protein or RNase3, is a basic, positively charged ribonuclease produced and stored in the specific granules of eosinophils. It is a member of the RNase A superfamily and is encoded by the RNASE3 gene.

Upon activation of eosinophils by cytokines such as IL-5 or GM-CSF, or by IgE-mediated stimuli, ECP is released through degranulation. The cationic nature of ECP promotes interactions with cell membranes and nucleic acids, contributing to its antimicrobial effects and cytotoxic potential.

Functionally, ECP has ribonuclease activity that can degrade RNA, exerting antiparasitic and antibacterial effects in vitro. However, outside of infectious contexts its release can contribute to tissue damage and inflammation, particularly in eosinophil-rich responses, with potential to affect airway and skin tissues.

Clinically, elevated ECP levels can be detected in serum, plasma, sputum, or other body fluids and are used as a biomarker of eosinophil activation. In allergic diseases such as asthma, allergic rhinitis, and atopic dermatitis, higher ECP levels may correlate with disease activity, airway inflammation, or treatment response, though they are not disease-specific and levels can be influenced by therapy or comorbid conditions.

Measurement is typically performed by immunoassays such as ELISA. ECP is one of several eosinophil-derived mediators, alongside major basic protein and eosinophil-derived neurotoxin, used to characterize eosinophil involvement in disease.