title: Comparison of lactoferrin activity in fresh and stored human milk.
abstract: OBJECTIVE
  Lactoferrin (Lf), the dominant protein in human milk (HM), has been shown to have anti-inflammatory and anti-microbial activity in the neonatal gut. Previous studies indicate that freezing significantly decreases the concentration of Lf in HM. The objective of our study was to compare the activity of Lf in fresh and frozen HM over time.
  
  
  METHODS
  HM samples were examined fresh and after storage at -20 °C for 3 and 6 months. Lf concentration was determined by enzyme-linked immunoassay, and the activity was measured by examination of nitric oxide (NO) production and tumor necrosis factor-α secretion from rat macrophages exposed to HM samples.
  
  
  RESULTS
  After 3 and 6 months at -20 °C, the average decrease in Lf concentrations was 55% and 65%, respectively. The bioactivity of Lf also decreased significantly over 6 months.
  
  
  CONCLUSIONS
  Freezing HM for 3 or more months significantly decreases Lf levels and activity. Periodically providing fresh HM may benefit vulnerable preterm neonates.
authors.affiliation: Division of Neonatal Medicine, Department of Pediatrics, University of Louisville, Louisville, KY, USA.
authors.forename: N A
authors.initials: NA
authors.lastname: Raoof
authors.affiliation: Division of Neonatal Medicine, Department of Pediatrics, University of Louisville, Louisville, KY, USA.
authors.forename: D H
authors.initials: DH
authors.lastname: Adamkin
authors.affiliation: Division of Neonatal Medicine, Department of Pediatrics, University of Louisville, Louisville, KY, USA.
authors.forename: P G
authors.initials: PG
authors.lastname: Radmacher
authors.affiliation: Division of Neonatal Medicine, Department of Pediatrics, University of Louisville, Louisville, KY, USA.|Division of Hematology/Oncology, Department of Medicine, University of Louisville, Louisville, KY, USA.
authors.forename: S
authors.initials: S
authors.lastname: Telang
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques; D002460:Cell Line; D061353:Food Storage / Q000592:standards*; D005615:Freezing; D006801:Humans; D007781:Lactoferrin / Q000737:chemistry*; D008264:Macrophages / Q000378:metabolism*; D008895:Milk, Human / Q000737:chemistry*; D009569:Nitric Oxide / Q000378:metabolism*; D051381:Rats; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
chemical_list: C490098:LTF protein, human; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide; D007781:Lactoferrin