title: Evidence for allergen-specific IgE of maternal origin in human placenta.
abstract: BACKGROUND
  Immunoglobulin E (IgE) has been identified on macrophage-like cells in the villi of human placenta, irrespective of the serum IgE levels or allergy status of the mother. The origin of placental IgE is debated and it is not known if it is spontaneously produced, so-called 'natural IgE', or if it has any specificity for certain allergens. The aim of this study was to investigate if placental IgE originates from mother or child and to analyse its specificity.
  
  
  METHODS
  Immunoglobulin E was eluted from placenta by lowering the pH. Total and allergen-specific IgEs were measured in placenta eluate, maternal and cord blood plasma by means of ImmunoCAP (Phadia AB). The levels of natural antibodies were determined with an anti-phosphorylcholine (PC) enzyme-linked immunosorbent assay, as natural IgE has been shown in one previous publication with this assay.
  
  
  RESULTS
  Detectable amounts of IgE were eluted from 11/12 full-term placentas. Natural (anti-PC) IgE antibodies were detected in low amounts in maternal plasma but not in the placental eluate or in cord blood plasma. There was a significant correlation between the amount of total IgE eluted from placenta and the levels of total IgE in maternal plasma; however, not between maternal and cord blood plasma. Allergen-specific IgE was only found in placental eluates from mothers with specific IgE towards these allergens. Furthermore, there was a significant correlation between the amount of allergen-specific IgE eluted from placenta and the levels of allergen-specific IgE in maternal plasma. Allergen-specific IgE could not be detected in cord blood.
  
  
  CONCLUSIONS
  These results suggest a maternal origin of placental IgE, which can be allergen-specific.
authors.affiliation: Clinical Allergy Research Unit, Department of Medicine Solna, Stockholm, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Joerink
authors.forename: E
authors.initials: E
authors.lastname: Rindsjö
authors.forename: F
authors.initials: F
authors.lastname: Stenius
authors.forename: J
authors.initials: J
authors.lastname: Alm
authors.forename: G
authors.initials: G
authors.lastname: Lilja
authors.forename: H
authors.initials: H
authors.lastname: Grönlund
authors.forename: A
authors.initials: A
authors.lastname: Scheynius
mesh_terms: D000328:Adult; D000485:Allergens / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005312:Fetal Blood / Q000276:immunology; D006801:Humans; D007073:Immunoglobulin E / Q000032:analysis* / Q000097:blood; D007150:Immunohistochemistry; D008875:Middle Aged; D010920:Placenta / Q000276:immunology*; D011247:Pregnancy
chemical_list: D000485:Allergens; D007073:Immunoglobulin E