[Is the seric eosinophil cationic protein level a valuable tool of diagnosis in clinical practice?]

The eosinophil cationic protein (ECP) is one of the mediators released during eosinophil activation. These cells are effector cells taking part into the Th2-lymphocyte dependent allergic inflammation. Assaying ECP concentrations in blood and sputum may be useful in evaluating allergic inflammation (asthma and rhinitis). This summary considers the value of measuring ECP levels for the diagnosis of various diseases where an eosinophil-mediated tissue inflammation plays a role.

Levels of eosinophil cationic protein have been determined in nasal secretions, sputum, gastric secretions, feces and serum. They are increased during seasonal allergic rhinitis and perennial rhinitis, allergic asthma and atopic dermatitis. They are also increased in various gastro-intestinal disorders, some of which are associated with IgE: eosinophil intestinal diseases (esophagitis, gastro-enteritis and colitis), gastro-intestinal food allergy and intestinal parasitoses. Finally, they are increased in non IgE-dependent disorders: non allergic asthma with aspirin intolerance, respiratory infections, sinonasal polyposis, Churg-Strauss disease and idiopathic hyper-eosinophilia (HES) syndrome.

Assaying serum ECP could help in the diagnosis of several diseases. With parasitic disease the pathogenic progression may be accurately assessed, when serological tests are less indicative. ECP assay may point to non allergic asthma, either Fernand-Widal syndrome or Churg-Strauss disease. As for gastro-intestinal disorders, it indicates an eosinophilic tissue reaction. In the event of isolated hypereosinophilia, ECP assay may clarify whether it is benign or tending towards idiopathic HES. The assay of peroxidase and eosinophil-derived neurotoxin (EDN) should be also considered.