title: Autoantibodies to αS1-casein are induced by breast-feeding.
abstract: BACKGROUND
  The generation of antibodies is impaired in newborns due to an immature immune system and reduced exposure to pathogens due to maternally derived antibodies and placental functions. During nursing, the immune system of newborns is challenged with multiple milk-derived proteins. Amongst them, caseins are the main constituent. In particular, human αS1-casein (CSN1S1) was recently shown to possess immunomodulatory properties. We were thus interested to determine if auto-antibodies to CSN1S1 are induced by breast-feeding and may be sustained into adulthood.
  
  
  METHODS
  62 sera of healthy adult individuals who were (n = 37) or were not (n = 25) breast-fed against human CSN1S1 were investigated by a new SD (surface display)-ELISA. For cross-checking, these sera were tested for anti Epstein-Barr virus (EBV) antibodies by a commercial ELISA.
  
  
  RESULTS
  IgG-antibodies were predominantly detected in individuals who had been nursed. At a cut-off value of 0.4, the SD-ELISA identified individuals with a history of having been breast-fed with a sensitivity of 80% and a specificity of 92%. Under these conditions, 35 out of 37 sera from healthy donors, who where breast-fed, reacted positively but only 5 sera of the 25 donors who were not breast-fed. The duration of breast-feeding was of no consequence to the antibody reaction as some healthy donors were only short term breast-fed (5 days minimum until 6 weeks maximum), but exhibited significant serum reaction against human CSN1S1 nonetheless.
  
  
  CONCLUSIONS
  We postulate that human CSN1S1 is an autoantigen. The antigenicity is orally determined, caused by breast-feeding, and sustained into adulthood.
authors.affiliation: Institute of Pharmaceutical and Medicinal Chemistry, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany.
authors.forename: Klaudia
authors.initials: K
authors.lastname: Petermann
authors.forename: Stefan
authors.initials: S
authors.lastname: Vordenbäumen
authors.forename: Ruth
authors.initials: R
authors.lastname: Maas
authors.forename: Achim
authors.initials: A
authors.lastname: Braukmann
authors.forename: Ellen
authors.initials: E
authors.lastname: Bleck
authors.forename: Thorsten
authors.initials: T
authors.lastname: Saenger
authors.forename: Matthias
authors.initials: M
authors.lastname: Schneider
authors.forename: Joachim
authors.initials: J
authors.lastname: Jose
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence; D001323:Autoantibodies / Q000097:blood*; D001483:Base Sequence; D001942:Breast Feeding; D002364:Caseins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007231:Infant, Newborn; D008895:Milk, Human / Q000737:chemistry* / Q000276:immunology*; D008969:Molecular Sequence Data
chemical_list: D001323:Autoantibodies; D002364:Caseins