title: Eosinophil cationic protein: is it useful in asthma? A systematic review.
abstract: BACKGROUND
  Eosinophil cationic protein (ECP) has been widely investigated as a potential biomarker of airway inflammation.
  
  
  METHODS
  A systematic review was performed using Medline with key terms eosinophil cationic protein and asthma, limiting the search to titles or abstracts. Out of 688 potential papers found, abstracts were reviewed based on the following criteria: (1) ECP was used as a biological marker, (2) asthma was the index disease studied, (3) it was a controlled clinical study and (4) ECP was assessed as a diagnostic, assessment or management tool. One hundred and sixty-nine articles satisfied the selection criteria and their full-text versions were reviewed. Only 53 papers were found to provide clinically useful information.
  
  
  RESULTS
  ECP has been measured in serum, plasma, sputum, saliva and broncho-alveolar lavage fluids but serum and sputum are the most established. Levels of ECP in normal and asthmatic subjects in various body fluids were identified. ECP correlates well with airway inflammation but not airway hyper-responsiveness. It is raised in other atopic diseases and hence is not diagnostic for asthma. However, it has been shown to be useful in assessing asthma severity, compliance with anti-inflammatory asthma therapy and as a guide to tailing down inhaled corticosteroid therapy. Although there is some evidence that ECP levels are affected by age, smoking, circadian rhythm and seasonal variation, only smoking appears to be of clinical significance.
  
  
  CONCLUSIONS
  Despite its limitations, ECP remains potentially useful in asthma management. Future research on ECP should focus on using serial measurements and combining it with other markers of asthma which may increase its clinical usefulness.
authors.affiliation: Department of Community, Occupational and Family Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Blk MD3, 16 Medical Drive, Singapore 117597, Singapore. cofkohch@nus.edu.sg
authors.forename: Gerald C-H
authors.initials: GC
authors.lastname: Koh
authors.forename: Lynette P-C
authors.initials: LP
authors.lastname: Shek
authors.forename: Daniel Y-T
authors.initials: DY
authors.lastname: Goh
authors.forename: Hugo
authors.initials: H
authors.lastname: Van Bever
authors.forename: David S-Q
authors.initials: DS
authors.lastname: Koh
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001249:Asthma / Q000276:immunology* / Q000628:therapy; D015415:Biomarkers / Q000032:analysis / Q000097:blood; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D002648:Child; D002940:Circadian Rhythm / Q000276:immunology; D047150:Eosinophil Cationic Protein / Q000032:analysis* / Q000097:blood; D006801:Humans; D007155:Immunologic Factors / Q000032:analysis* / Q000097:blood; D012463:Saliva / Q000737:chemistry; D012621:Seasons; D012907:Smoking / Q000009:adverse effects; D013183:Sputum / Q000737:chemistry
chemical_list: D015415:Biomarkers; D007155:Immunologic Factors; D047150:Eosinophil Cationic Protein