Identification and characterization of linear B-cell epitopes of beta-globulin, a major allergen of sesame seeds.
BACKGROUND
The increased consumption of foods containing sesame seeds is paralleled by an increase in reported sesame-induced allergic reactions.


OBJECTIVE
This study aimed at identifying and characterizing the linear B-cell epitopes of the 14-kd beta-globulin, the major allergen of sesame seed.


METHODS
A peptide containing 71 amino acids (peptide B) was previously identified by us as the IgE-binding region on beta-globulin. To determine the amino acid sequence of the IgE-binding sites on peptide B, we synthesized overlapping peptides 20 and 10 amino acid residues long that span the entire length of peptide B, which were offset from each other by 10 and 2 amino acid residues, respectively. Sera from 20 subjects given diagnoses of allergy to sesame beta-globulin served to identify the epitopes by using the dot-blot test.


RESULTS
At least 9 different IgE-recognition sites were identified on peptide B. Three of them, numbers 2, 3, and 13 (corresponding to amino acids 46-55, 48-57, and 76-86, respectively, in the beta-globulin sequence), appeared to be immunodominant IgE-binding epitopes. Also, these peptides were best recognized in terms of intensity of response. There was no obvious sequence motif shared by the 9 different IgE-binding epitopes of beta-globulin. However, approximately 60% of the amino acids represented in the epitopes are hydrophobic residues.


CONCLUSIONS
Identification of the IgE-binding epitopes might provide a better understanding of the functional role the allergens play in the disease and might have implications for immunodiagnosis and probably immunotherapy.
Wolff
Neomi
N
Department of Biotechnology and Food Engineering, Technion-Institute of Technology, Haifa 32000, Israel.
Yannai
Shmuel
S
Karin
Nathan
N
Levy
Yael
Y
Reifen
Ram
R
Dalal
Ilan
I
Cogan
Uri
U
D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000276:immunology*; D000595:Amino Acid Sequence; D001609:Beta-Globulins / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D018985:Epitopes, B-Lymphocyte; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology; D007223:Infant; D008969:Molecular Sequence Data; D012639:Seeds / Q000276:immunology*; D031685:Sesamum / Q000276:immunology*
D000485:Allergens; D001609:Beta-Globulins; D018985:Epitopes, B-Lymphocyte; D007073:Immunoglobulin E