Identification of the Critical Amino Acid Residues of Immunoglobulin E and Immunoglobulin G Epitopes in α-Lactalbumin by Alanine Scanning Analysis.

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α-Lactalbumin represents one of the major allergens causing cow milk allergy. Few studies have clearly evaluated immunological relationships between immunoglobulin E (IgE) and immunoglobulin G (IgG)-binding epitopes of α-lactalbumin. IgE- and IgG-binding epitopes were immunolabeled with individual sera from cow milk-allergic patients. Alanine scanning of immunodominant epitopes was used to identify the critical amino acid (aa). Our initial data revealed Val8 , Phe9 , Arg10 , Tyr103 , Leu105 , and His107 were the critical aa for IgE-binding epitope. The critical aa of IgG-binding epitopes were Phe9 , Leu15 , Pro24 , Trp26 , and His32 . This study will provide necessary information to alter the cDNA to encode a protein capable of activating milk-specific T cells, but with reduced IgE- or IgG-binding capacity.