egg allergy: new allergens and molecular diagnosis

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Egg allergy: new allergens and molecular diagnosis Presented by Suparat Sirivimonpan, MD. September7, 2012

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  • 1. Egg Allergy 7/9/2012 Suparat Sirivimonpan,MD.
  • 2. Egg allergyIntroductionPrevalence Egg allergen : new allergen Diagnosis : molecular diagnosis
  • 3. Introduction Egg allergy may be defined as an adverse reaction of immunologic nature induced by egg proteins IgE ,non-IgE , mixed IgE-mediated disorders hens egg allergy is the second most common food allergy in infants and young children closely associated with atopic dermatitis Increase risks of sensitization to aeroallergens and asthma in children with egg allergy Pediatr Clin N Am 2011;58:427443
  • 4. Prevalence estimated prevalence : varies depending on method of data collection or definition A meta-analysis of the prevalence of egg allergy in children Self-reported prevalence : up to 7% challenge-confirmed egg allergy : up to 1.7% Allergy 2010; 65: 283289
  • 5. PrevalenceIn Thailand Santadusit S, et al. Egg allergy : 1.52% J Med Assoc Thai 2005;88:S27-32 Unpublished data 2012, Chulalongkorn university egg allergy : 1.1% (parent reported and physician diagnosis) in young children
  • 6. Egg allergen
  • 7. Egg allergens 5 major allergenic proteins : Gal d 1 to Gal d 5 (Gallus domesticus) Curr Allergy Asthma Rep 2006;6(2):14552
  • 8. Egg White allergen
  • 9. Egg white allergens Allergy 2010; 65: 283289
  • 10. Ovomucoid dominant allergen in egg unique characteristics relative stability against heat and digestion with proteinases presence of strong disulfide bonds that stabilize protein children with persistent egg allergy had significantly higher specific IgE levels to OVM than children who outgrew their egg allergy A favorable prognosis was associated with the absence or a decline in OVM-specific IgE titers Allergy 2007; 62:758765 Curr Opin Allergy Clin Immunol 2011, 11:210215
  • 11. Ovalbumin heat-labile and less allergenic IgE-binding epitopes on OVA might be destroyed after heating : children who have specific IgE primarily to OVA are likely to tolerate heated egg Curr Opin Allergy Clin Immunol 2011, 11:210215
  • 12. Ovalbumin The Maillard reaction occurs between reducing sugars and proteins during thermal processing of foods It produces chemically glycated proteins termed advanced glycation end products (AGEs) T-cell immunogenicity of chemically glycated ovalbumin The glycation structures of AGEs are suggested to function as pathogenesis-related immune epitopes in food allergy J Allergy Clin Immunol 2010;125:175-83.
  • 13. Newly identified egg white allergen Allergology International. 2010;59:175-183
  • 14. Diluted egg white proteins were separated by 2-dimensional (2-D) gel electrophoresis 63 spots Allergology International. 2010;59:175-183
  • 15. Immunolabeling was performed on individual patient sera 19 child patients with egg white allergy 11 negative control subjects19 patients 11 negative control subjects-Aged 2.2 1.7 years -Aged 4.0 3.7 years-Total IgE 434.1 424.7 Iuml -no clinical history of any allergic-Diagnosis was based on clinical history symptomsand CAP-RAST results to hens eggwhite-Open food challenges : 9/19 patients Allergology International. 2010;59:175-183
  • 16. Allergology International. 2010;59:175-183
  • 17. 15/25 Spots of egg white proteins that bound to the patients IgE were identified by mass spectrometry-based proteomics 10/25 Allergology International. 2010;59:175-183
  • 18. Identification of IgE-reactive spots spots were excised digested in-gel with trypsin The resulting peptide mixtures were analyzed by26% pt LC-MS/MS (Liquid chromatographytandem mass16% pt spectrometry) L-PGDS MALDI-TOF/MS (matrix assisted laser desorption(1 anaphylaxis) ionization time of flight mass spectrometry)53% pt Allergology International. 2010;59:175-183
  • 19. L-PGDS Cystatin Reaction to LPGDS and cystatin was confirmed using each purified protein Allergology International. 2010;59:175-183
  • 20. Ch21 protein and L-PGDS Ch21 protein and L-PGDS belong to the lipocalin Family has been reported as allergenic Ch21 protein and L-PGDS were minor allergens However, the sera from patient (MT,HS), which reacted to spot no. 28 did not seem to react to the major spots, such as nos. 3, 4, 5, 48, or 49 not only the hidden allergen components, but there are some patients who are preferentially reacting to those minor egg allergens minor allergen does not always mean that it is allergenically poor Allergology International. 2010;59:175-183
  • 21. Ch21 protein and L-PGDS PGD2 synthesized by L-PGDS is related to allergic inflammation in vivo and that L-PGDS from chicken shows PGDS activity These reports suggest that L-PGDS induces allergic reactions in addition to binding to IgE, and that PGD2 may exist in eggs Allergology International. 2010;59:175-183
  • 22. Cystatin cysteine protease inhibitor allergen in cats and dogs considered to be a major allergen because it showed high reactivity to IgE from patients with egg allergy 2 possible reasons for the lack of literature on cystatin as an allergen similarity in molecular weight of cystatin and lysozyme, a major allergen, makes it difficult identify cystatin without using 2-D gel electrophoresis presence of only a small amount of cystatin in eggs makes it difficult to identify without development of LC-MSMS Allergology International. 2010;59:175-183
  • 23. Egg yolk allergen
  • 24. Egg yolk allergens alpha-livetin or chicken serum a

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