title: Effect of simulated gastro-duodenal digestion on the allergenic reactivity of beta-lactoglobulin.
abstract: BACKGROUND
  Cow's milk (CM) allergy affects about 2% of infants. The allergenicity of dietary proteins, including those from CM, has been related to their digestibility although the generality of the link and its causality remains to be demonstrated. In this study we use an in vitro digestion system, to investigate the digestibility of β-lactoglobulin (blg) during gastrointestinal transit and to assess the impact of this process on blg allergenic reactivity in CM allergic children.
  
  
  METHODS
  Blg digesta were prepared using an in vitro digestion protocol simulating either gastric digestion alone or followed by duodenal digestion with or without phosphatidylcholine (PC). Biochemical analysis of blg digesta was performed by SDS-PAGE and their concentration was measured by a sandwich ELISA. Assessment of their allergenic reactivity was done in vitro by EAST inhibition, specific basophil activation (basotest) and lymphocyte proliferation (PCNA-flow cytometry) assays using sera and cells from patients allergic to blg and in vivo by skin prick testing (SPT) of these patients.
  
  
  RESULTS
  Blg was only broken down to smaller peptides after gastro-duodenal digestion although a sizeable amount of intact protein still remained. Digestion did not modify the IgE binding capacity of blg except for gastro-duodenal digestion performed in the absence of PC. These results are consistent with the quantity of intact blg remaining in the digesta. Overall both gastric and gastroduodenal digestion enhanced activation of sensitized basophils and proliferation of sensitized lymphocytes by blg. However, there was a tendency towards reduction in mean diameter of SPT following digestion, the PC alone during phase 1 digestion causing a significant increase in mean diameter.
  
  
  CONCLUSIONS
  Digestion did not reduce the allergenic reactivity of blg to a clinically insignificant extent, PC inhibiting digestion and thereby protecting blg allergenic reactivity. SPT reactivity was reduced compared to blg immunoreactivity in in vitro tests.
authors.affiliation: Athens University, P. & A. Kyriakou Children's Hospital, Athens, Greece.|Krefting Research Centre, Department of Internal Medicine, Institute of Medicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Apostolos
authors.initials: A
authors.lastname: Bossios
authors.affiliation: Athens University, P. & A. Kyriakou Children's Hospital, Athens, Greece.|Thessaly University Hospital, Larissa, Greece.
authors.forename: Maria
authors.initials: M
authors.lastname: Theodoropoulou
authors.affiliation: Lab d'Immuno-Allergie Alimentaire, INRA-CEA, Saclay, France.|DBV Technologies, 92220, Bagneux, France.
authors.forename: Lucie
authors.initials: L
authors.lastname: Mondoulet
authors.affiliation: Institute of Food Research, Norwich Research Park, Colney NR4 7UA UK.
authors.forename: Neil M
authors.initials: NM
authors.lastname: Rigby
authors.affiliation: Athens University, P. & A. Kyriakou Children's Hospital, Athens, Greece.
authors.forename: Nikolaos G
authors.initials: NG
authors.lastname: Papadopoulos
authors.affiliation: Lab d'Immuno-Allergie Alimentaire, INRA-CEA, Saclay, France.
authors.forename: Hervé
authors.initials: H
authors.lastname: Bernard
authors.affiliation: Lab d'Immuno-Allergie Alimentaire, INRA-CEA, Saclay, France.
authors.forename: Karine
authors.initials: K
authors.lastname: Adel-Patient
authors.affiliation: Lab d'Immuno-Allergie Alimentaire, INRA-CEA, Saclay, France.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Wal
authors.affiliation: Institute of Food Research, Norwich Research Park, Colney NR4 7UA UK.
authors.forename: Clare En
authors.initials: CE
authors.lastname: Mills
authors.affiliation: Athens University, P. & A. Kyriakou Children's Hospital, Athens, Greece.
authors.forename: Photini
authors.initials: P
authors.lastname: Papageorgiou