title: Effect of gestation length on the levels of five innate defence proteins in human milk.
abstract: BACKGROUND
  Human milk contains a range of host defence proteins that appear to contribute to health and wellbeing, but their variability in abundance among individuals has not been very well characterised. Milk from mothers of premature infants has altered composition, but the effect of gestation length on the host-defence properties of milk is not known. A study was therefore undertaken to determine the variability and effect of gestation length on the abundance of five host-defence proteins in milk; lactoferrin, secretory IgA, IgG, secretory component, and complement C3.
  
  
  METHODS
  Milk was obtained from 30 mothers at their second and fifth week of lactation. These were from three groups of ten mothers having had very premature (V; 28-32 weeks gestation), premature (P; 33-36 weeks) or full term deliveries (T; 37-41 weeks). The concentration of each of the five proteins was measured in each milk sample by either ELISA or quantitative western blotting.
  
  
  RESULTS
  The concentration of IgG, and complement C3 ranged 22- and 17-fold respectively between mothers, while lactoferrin, secretory IgA, and secretory component ranged 7-, 9-, and 4-fold, respectively. The V group had significantly lower concentrations of four of the five proteins, the exception being IgG. Levels of these four proteins also decreased between weeks 2 and 5 of lactation in the P and T groups. Significant correlation was found between the concentrations of the host defence proteins within individual mothers, indicating some degree of co-ordinate regulation.
  
  
  CONCLUSIONS
  Mothers vary widely in the levels of host defence proteins in milk. Very short gestation length results in decreased abundance of host-defence proteins in milk. This may have functional implications for very premature infants.
authors.affiliation: AgResearch, Ruakura Research Centre, Hamilton, New Zealand.
authors.forename: Marita
authors.initials: M
authors.lastname: Broadhurst
authors.affiliation: AgResearch, Ruakura Research Centre, Hamilton, New Zealand.
authors.forename: Keryn
authors.initials: K
authors.lastname: Beddis
authors.affiliation: Neonatal Unit, Waikato Hospital, Private Bag 3200, Hamilton, New Zealand.
authors.forename: Janet
authors.initials: J
authors.lastname: Black
authors.affiliation: AgResearch, Ruakura Research Centre, Hamilton, New Zealand.
authors.forename: Harold
authors.initials: H
authors.lastname: Henderson
authors.affiliation: Neonatal Unit, Waikato Hospital, Private Bag 3200, Hamilton, New Zealand.
authors.forename: Arun
authors.initials: A
authors.lastname: Nair
authors.affiliation: AgResearch, Ruakura Research Centre, Hamilton, New Zealand. Electronic address: tom.wheeler@agresearch.co.nz.
authors.forename: Thomas
authors.initials: T
authors.lastname: Wheeler
mesh_terms: D000328:Adult; D003176:Complement C3 / Q000032:analysis*; D005260:Female; D005865:Gestational Age; D006801:Humans; D007136:Immunoglobulins / Q000032:analysis*; D007774:Lactation / Q000378:metabolism; D007781:Lactoferrin / Q000032:analysis*; D008895:Milk, Human / Q000737:chemistry* / Q000276:immunology; D011247:Pregnancy
chemical_list: D003176:Complement C3; D007136:Immunoglobulins; D007781:Lactoferrin
keywords: Complement C3; Immunoglobulin A; Immunoglobulin G; Lactoferrin; Secretory component protein