Characterization of the T-cell epitopes of a major peanut allergen, Ara h 2.
BACKGROUND
The development of safe and effective immunotherapy for peanut allergy has been complicated by the high anaphylactic potential of native peanut extracts. We sought to map the T-cell epitopes of the major peanut allergen, Ara h 2 in order to develop T-cell targeted vaccines.


METHODS
A panel of eight peanut-specific CD4+ T-cell lines (TCL) was derived from eight peanut-allergic subjects and proliferative and cytokine responses to stimulation with a set of overlapping 20-mer peptides representing the entire sequence of Ara h 2 determined. Proliferation was assessed in 72 h assays via tritiated thymidine incorporation, while interleukin (IL)-5 and interferon (IFN)-gamma production were assessed via sandwich enzyme-linked immunosorbent assay (ELISA) of cell culture supernatants.


RESULTS
Eight of the 17 Ara h 2 peptides were recognized by one or more subjects, with the two peptides showing highest reactivity [Ara h 2 (19-38) and Ara h 2 (73-92)] being recognized by three subjects each. Adjoining peptides Ara h 2 (28-47) and Ara h 2 (100-119) induced proliferative responses in two subjects. Each of these peptides was associated with a Th2-type cytokine response.


CONCLUSIONS
Two highly immunogenic T-cell reactive regions of Ara h 2 have been identified, Ara h 2 (19-47) and Ara h 2 (73-119), providing scope for the development of safe forms of immunotherapy for peanut allergy.
Glaspole
I N
IN
Department of Allergy, Immunology and Respiratory Medicine, Alfred Hospital, Melbourne, Australia.
de Leon
M P
MP
Rolland
J M
JM
O'Hehir
R E
RE
D055516:2S Albumins, Plant; D000328:Adult; D052179:Antigens, Plant; D015153:Blotting, Western; D002460:Cell Line; D049109:Cell Proliferation; D016207:Cytokines / Q000096:biosynthesis; D018604:Epitope Mapping; D018984:Epitopes, T-Lymphocyte; D005260:Female; D006023:Glycoproteins / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D008297:Male; D008875:Middle Aged; D021183:Peanut Hypersensitivity / Q000276:immunology*; D010446:Peptide Fragments / Q000276:immunology; D010940:Plant Proteins; D013601:T-Lymphocytes / Q000166:cytology; D018418:Th2 Cells / Q000378:metabolism
D055516:2S Albumins, Plant; D052179:Antigens, Plant; C078642:Ara h II protein, Arachis hypogaea; D016207:Cytokines; D018984:Epitopes, T-Lymphocyte; D006023:Glycoproteins; D010446:Peptide Fragments; D010940:Plant Proteins; D007073:Immunoglobulin E