Eosinophil Cationic Protein (ECP) / Ribonuclease 3

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Turnaround Time: 4 - 7 days
CPT Code:


Test Type: 0.5 mL Serum
Stability Time:



Room temperature

5 days


14 days


14 days

Freeze/thaw cycles

Stable x3

Reference Range:

4−54 μg/L


Eosinophils are effector cells that play a role in allergic and nonallergic inflammation.1,2 The most prominent feature of these cells is large cytoplasmic granules, each containing four basic proteins, the most plentiful of which is eosinophil cationic protein (ECP).3 ECP is a protein with ribonuclease activity that is released during eosinophil activation. While the full physiologic role of ECP has not been completely defined, this protein has been attributed with cytotoxic, neurotoxic, fibrosis-promoting, and immune-regulatory functions.1,3,4 Studies suggest that ECP may play a role in regulating mucosal and immune cells and may directly fight parasitic, bacterial, and viral infections.3

ECP is often elevated in diseases in which an eosinophil-mediated tissue inflammation plays a role.1,3,5 Measuring ECP levels has been used to evaluate eosinophil-mediated allergic inflammation, asthma, and rhinitis.1 Levels can be increased during both seasonal and perennial rhinitis1,6 and may reflect current allergen exposure.1,6 In atopic dermatitis, ECP has been shown to correlate with the symptoms and total clinical score.7

Eosinophilic inflammation is a relatively common feature of asthma.4,6,8-10 Although not diagnostic for asthma, elevated ECP levels are thought to reflect the degree of asthma-related bronchial eosinophilic inflammation.6,11 Increased ECP levels correspond to symptom onset and can precede bronchial hyper-reactivity.1,4 ECP has been used to assess asthma severity and support the management of anti-inflammatory therapy.5,11,12 It should be noted, however, that ECP is better correlated to symptom score than to lung function parameters, especially in children with mild and moderate asthma.6

ECP levels can be increased in a number of gastrointestinal disorders, including eosinophil intestinal diseases (esophagitis, gastroenteritis, and colitis), gastrointestinal food allergy, and intestinal parasitoses.1 ECP levels can also be increased in non−IgE-mediated conditions, including nonallergic asthma with aspirin intolerance, respiratory infections, sinonasal polyposis, and idiopathic hypereosinophilia (HES) syndrome.1,3 ECP has also been used as a disease activity marker in Churg-Strauss syndrome (CSS), a condition that is also known as allergic granulomatosis or allergic angiitis.13 CSS is a disorder marked by blood vessel inflammation that can restrict blood flow to vital organs and tissues, sometimes permanently damaging them.1,12 In a recent study, Niccoli and coworkers showed that ECP levels independently predicted the severity of coronary artery disease in patients with angina.14

BD plastic serum-separator tubes should not be used as they will produce erroneous results.

Results for this test are for investigational purposes only by the assay's manufacturer. The performance characteristics of this product have not been established. Results should not be used as a diagnostic procedure without confirmation of the diagnosis by another medically established diagnostic product or procedure.

1. Moneret-Vautrin DA. Is the seric eosinophil cationic protein level a valuable tool of diagnosis in clinical practice? Rev Med Interne. 2006 Sep; 27(9):679-683. PubMed 16647168

2. Venge P, Byström J, Carlson M, et al. Eosinophil cationic protein (ECP): Molecular and biological properties and the use of ECP as a marker of eosinophil activation in disease. Clic Exp Allergy. 1999 Sep; 29(9):1172-1186. PubMed 10469025

3. Bystrom J, Amin K, Bishop-Bailey D. Analysing the eosinophil cationic protein—A clue to the function of the eosinophil granulocyte. Respir Res. 2011 Jan 14; 12:10. PubMed 21235798

4. Tomassini M, Magrini L, De Petrillo G, et al. Serum levels of eosinophil cationic protein in allergic diseases and natural allergen exposure. J Allergy Clin Immunol. 1996 Jun; 97(6):1350-1355. PubMed 8648032

5. Venge P. Monitoring the allergic inflammation. Allergy. 2004 Jan; 59(1):26-32. PubMed 14674929

6. Prehn A, Seger RA, Faber J, et al. The relationship of serum-eosinophil cationic protein and eosinophil count to disease activity in children with bronchial asthma. Pediatr Allergy Immunol. 1998 Nov; 9(4):197-203. PubMed 9920218

7. Czech W, Krutmann J, Schöpf E, Kapp A. Serum eosinophil cationic protein (ECP) Is a sensitive measure for disease activity in atopic dermatitis. Br J Dermatol. 1992 Apr; 126(4):351-355. PubMed 1571256

8. Sorkness C, McGill K, Busse WW. Evaluation of serum eosinophil cationic protein as a predictive marker for asthma exacerbation in patients with persistent disease. Clin Exp Allergy. 2002 Sep; 32(9):1355-1359. PubMed 12220475

9. Peona V, De Amici M, Quaglini S, et al. Serum eosinophilic cationic protein: Is there a role in respiratory disorders. J Asthma. 2010 Mar; 47(2):131-134. PubMed 20170318

10. Niimi A, Amitani R, Suzuki K, Tanaka E, Murayama T, Kuze F. Serum eosinophil cationic protein as a marker of eosinophilic inflammation in asthma. Clin Exp Allergy. 1998 Feb; 28(2):233-240. PubMed 9515598

11. Koh GC, Shek LP, Goh DY, Van Bever H, Koh DS. Eosinophil cationic protein: Is it useful in asthma? A systematic review. Respir Med. 2007 Apr; 101(4):696-705. PubMed 17034998

12. ImmunoCAP ECP Conjugate 50 [Package insert] Portage, Mich: USA Phadia US Inc. Dec 9, 2010.

13. Guilpain P, Auclair JF, Tamby MC, et al. Serum eosinophil cationic protein: A marker of disease activity in Churg-Strauss syndrome. Ann N Y Acad Sci. 2007 Jun; 1107:392-399. PubMed 17804567

14. Niccoli G, Ferrante G, Cosentino N, et al. Eosinophil cationic protein: A new biomarker of coronary atherosclerosis. Atherosclerosis. 2010 Aug; 211(2):606-611. PubMed 20307883

Esoteric Immunoassay Department. ECP Method Validation Plan. Calabasas Hills, Calif: Esoterix, March 24, 2011.

Laboratory Notebook. NOQS-BN-ECP-064, LabCorp, Mar 31, 2011.

Laboratory Raw Data Binder. NOQS-BN-ECP-01, Mar 31, 2011.

Phadia 1000 User's Manual. Version 1.3 Using Phadia Software Version 2.20, Issued Oct, 2010, Phadia AB, PO Box 6460, SE-751 37 Uppsala, Sweden.

Collection Details:

Collection Instructions:

NMR lipoprofile serum-separator tube (N° 60360).

Other tubes should not be used as they may produce erroneous results.

Allow the sample to stand for 60 to 120 minutes to release the ECP in the cells prior to centrifugation. Separate the serum after 60 to 120 minutes and transfer to a plastic transport tube.