Methods for characterizing antibody binding affinity and epitope diversity in food allergy

A method for diagnosing whether a cow's milk allergic child is likely to outgrow a cow's milk allergy, which method comprises:

• (a) incubating an antibody-containing sample obtained from the child with a peptide library immobilized on a solid support to form an incubation mixture, wherein the peptide library comprises at least one epitope consisting of an amino acid sequence selected from the group consisting of FPEVFGKEKVNELSKDI (SEQ ID NO:
• 6);
• QKHIQKEDVPSERYLGYL (SEQ ID NO:
• 7);
• LEIVPNSAEERLHS (SEQ ID NO:8);
• AWYYVPLGTQYTDAPSF (SEQ ID NO:
• 9);
• INPSKENLCSTFCKEVV (SEQ ID NO:
• 10);
• EVDDEALEKFDKAL (SEQ ID NO:
• 11);
• RFFSDKIAKYIPIQYVL (SEQ ID NO:
• 12);
• DSPEVIESPPEINTVQV (SEQ ID NO:
• 13);
• CKEVVRNANEEEYS (SEQ ID NO:
• 14);
• and QTPVVVPPFLQPEV (SEQ ID NO:
• 15);
• (b) incubating a first portion of the incubation mixture with a competitor (competition protocol), wherein the competitor comprises the amino acid sequence of the at least one epitope set forth in (a), and incubating a second portion of the incubation mixture under the same conditions but in the absence of the competitor (standard protocol);
• (c) detecting IgE antibody binding to the at least one epitope in the peptide library in the competition protocol and in the standard protocol;
• (d) determining the binding affinity of the IgE antibody binding to the at least one epitope in the peptide library detected in step (c);
• and
• (e) diagnosing the child as not likely to outgrow the cow's milk allergy if the sample comprises an IgE antibody that binds to the at least one epitope in the peptide library with high affinity;
• or diagnosing the child as likely to outgrow the cow's milk allergy if the sample does not comprise an IgE antibody that binds to the at least one epitope in the peptide library with high affinity.