title: A dual-monoclonal sandwich ELISA specific for hepcidin-25.
abstract: BACKGROUND
  Hepcidin, a key regulator of iron metabolism, binds to the iron transporter ferroportin to cause its degradation. In humans, hepcidin deficiency has been linked to hemochromatosis and iron overload, whereas increased concentrations have been reported in anemia of cancer and chronic disease. There is currently an unmet clinical need for a specific immunoassay with a low limit of quantification to measure serum concentrations of hepcidin-25, the active form of the protein.
  
  
  METHODS
  We generated 2 antihepcidin-25 monoclonal antibodies and used them to build a sandwich ELISA. We correlated ELISA results to hepcidin-25 measurements by LC-MS and used ELISA to measure serum hepcidin-25 concentrations in normal individuals, cancer patients, and patients with rheumatoid arthritis.
  
  
  RESULTS
  The sandwich ELISA was highly specific for hepcidin-25, having a limit of quantification of 0.01 μg/L (10 pg/mL). Serum concentrations of hepcidin-25 measured by ELISA correlated with hepcidin-25 concentrations measured by using an independent LC-MS assay (r = 0.98, P < 0.001). Hepcidin-25 concentrations were increased in patients with cancer (median 54.8 μg/L, 25%-75% range 23.2-93.5 μg/L, n = 34) and rheumatoid arthritis (median 10.6 μg/L, 25%-75% range 5.9-18.4 μg/L, n = 76) compared with healthy individuals (median 1.20 μg/L, 25%-75% range 0.42-3.07 μg/L, n = 100).
  
  
  CONCLUSIONS
  The use of 2 monoclonal antibodies in a sandwich ELISA format provides a robust and convenient method for measuring concentrations of the active form of hepcidin. This ELISA should help to improve our understanding of the role of hepcidin in regulating iron metabolism.
authors.affiliation: Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA.
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Butterfield
authors.forename: Peng
authors.initials: P
authors.lastname: Luan
authors.forename: Derrick R
authors.initials: DR
authors.lastname: Witcher
authors.forename: Joseph
authors.initials: J
authors.lastname: Manetta
authors.forename: Anthony T
authors.initials: AT
authors.lastname: Murphy
authors.forename: Victor J
authors.initials: VJ
authors.lastname: Wroblewski
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Konrad
mesh_terms: D000293:Adolescent; D000328:Adult; D000911:Antibodies, Monoclonal; D023181:Antimicrobial Cationic Peptides / Q000097:blood* / Q000276:immunology; D001172:Arthritis, Rheumatoid / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D064451:Hepcidins; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000097:blood; D044469:Racial Groups; D012016:Reference Values; D012737:Sex Factors; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D055815:Young Adult
chemical_list: D000911:Antibodies, Monoclonal; D023181:Antimicrobial Cationic Peptides; D064451:Hepcidins; C545475:hepcidin 25, human