Specificity of IgE antibodies to sequential epitopes of hen's egg ovomucoid as a marker for persistence of egg allergy.
BACKGROUND
Approximately two-thirds of egg-allergic infants become tolerant within the first 5 years of life.


OBJECTIVE
We sought (1) to compare the recognition of sequential (linear) and conformational binding sites of ovomucoid, ovalbumin and ovotransferrin, by IgE antibodies of children with persistent and transient egg allergy, (2) to identify immunodominant IgE-and IgG-binding epitopes of ovomucoid, and (3) to compare epitope-specificity of IgE antibodies between patients with differing natural histories of egg allergy.


METHODS
Using immunodot-blots or ImmunoCAPs, IgE-antibodies against conformational (native) and sequential (reduced and alkylated) egg proteins were determined at the time of clinical reactivity in patients who retained their allergy and in those who developed clinical tolerance. IgE- and IgG-binding epitopes were mapped for ovomucoid using overlapping decapeptides on SPOTs membranes. Recognition of the major IgE-binding epitopes were compared between patients with differing natural histories of egg allergy.


RESULTS
The patients with long-lasting egg allergy had a higher concentrations of IgE antibodies against sequential and native ovomucoid and ovalbumin than the children who subsequently gained tolerance (P < 0.01). Four major IgE-binding epitopes were identified in ovomucoid at amino acid 1-10, 9-20, 47-56, and 113-124. IgE antibodies of all seven patients with persistent egg allergy recognized these epitopes whereas none of the 11 children who outgrew their egg allergy did so.


CONCLUSIONS
Patients with persistent egg allergy develop IgE antibodies against more sequential and conformational epitopes of ovomucoid and ovalbumin. The presence of serum IgE antibodies to specific sequential epitopes of ovomucoid may be used as a screening instrument for persistent egg allergy.
Järvinen
K-M
KM
Division of Pediatric Allergy & Immunology and Jaffe Institute for Food Allergy, The Mount Sinai School of Medicine, New York, NY 10029-6574, USA.
Beyer
K
K
Vila
L
L
Bardina
L
L
Mishoe
M
M
Sampson
H A
HA
D000293:Adolescent; D000918:Antibody Specificity; D015415:Biomarkers; D002648:Child; D002675:Child, Preschool; D021181:Egg Hypersensitivity / Q000175:diagnosis*; D004527:Egg Proteins / Q000276:immunology; D005500:Follow-Up Studies; D006801:Humans; D007108:Immune Tolerance; D016056:Immunodominant Epitopes / Q000032:analysis*; D007073:Immunoglobulin E / Q000276:immunology*; D007223:Infant; D007518:Isoantibodies / Q000097:blood*; D010047:Ovalbumin / Q000276:immunology; D010059:Ovomucin / Q000276:immunology*
D015415:Biomarkers; D004527:Egg Proteins; D016056:Immunodominant Epitopes; D007518:Isoantibodies; D010059:Ovomucin; D007073:Immunoglobulin E; D010047:Ovalbumin