A New Luminex-Based Peptide Assay to Identify Different Degrees of Milk Allergic Reactivity

FEBRUARY 2015 AB36 Abstracts S A T U R D A Y 110 A New Luminex-Based Peptide Assay to Identify Different Degrees of Milk Allergic Reactivity Cansin Sackesen, MD, Jing Lin, PhD, Stephanie Schmidt, BSc, Robert C. Getts, PhD, Jim Kadushin, PhD, Gustavo Gimenez, MSc, Ebru Arik Yilmaz, MD, Ozlem Cavkaytar, MD, Ozge Soyer, MD, Galina Grishina, MSc, Ludmilla Bardina, MSc, Hugh A. Sampson, MD; Icahn School of Medicine at Mount Sinai, New York, NY, Hacettepe University School of Medicine, Ankara, Turkey, Genisphere, LLC, PA, Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, NY, USA. RATIONALE: A novel Luminex-based peptide assay (LPA) was used to identify IgE binding to allergenic epitopes in milk-allergic Turkish children who tolerated different forms of milk products in oral food challenges. We sought to establish whether LPA results could distinguish patients’ clinical reactivity to different forms of milk, e.g. baked-milk (muffin), yoghurt-cheese, and whole unprocessed milk. METHODS: Four groups of milk allergic children were identified by oral food challenge to muffin, yoghurt-cheese and whole milk: 1.Reactive to baked-milk (n520), 2.Reactive to yoghurt-cheese/tolerant to muffin (n517), 3.Reactive to milk/tolerant to muffin and yoghurt-cheese (n523), and 4.Outgrown milk allergy (n532). Milk, casein, and b-lactoglobulin sIgE and sIgG4 were determined by UniCAP;IgE and IgG4 binding to milk protein epitopes were assessed by LPA. RESULTS: Children reactive to baked-milk had the highest milk, casein and b-lactoglobulin sIgE followed by children reactive to yoghurt-cheese. In analyzing children with positive milk protein epitope-specific binding, LPA revealed the most diverse binding patterns of IgE in the baked-milk reactive group: as1-casein (12-peptides), as2-casein (8-peptides), b-casein (8-peptides), b-lactoglobulin (3-peptides) and k-casein (3-peptides). Binding of IgE was observed only in as1-casein and as2-casein regions in children reactive to yoghurt-cheese and there was no IgE binding to any peptides in groups #3 and #4. IgG4 binding patterns were similar in all four groups. CONCLUSIONS: Using a novel high-through-put LPA, we were able to successfully distinguish the reactivity and diversity of IgE binding to allergenic epitopes in the most severe milk allergy phenotypes. This assay may be useful in distinguishing different degrees of milk allergy.