Modification of T-cell receptor Vbeta repertoire in response to allergen stimulation in peanut allergy.
BACKGROUND
Peanut is one of the most common foods causing allergic reactions and is the most common cause of fatal and near-fatal food-related anaphylaxis. Little is known of the immunologic mechanisms that underlie peanut allergy.


OBJECTIVE
In this study we examined clonality of the T-cell response (TCR) to peanut in MHC class II identical, peanut allergy-discordant sibling pairs.


METHODS
Four sibling pairs were investigated. The TCR repertoire was analyzed before and after in vitro stimulation of PBMCs with crude peanut or PHA, as control for general/nonspecific reactivity. Eighteen TCR-Vbeta families were examined by flow cytometry. Where significant differences in incidence of particular TCR-Vbeta families were observed, PCR familyspecific cDNA amplification and gene scanning were performed.


RESULTS
After stimulation with peanut, no selective expansion of any TCR-Vbeta subpopulation was observed with flow cytometry, in either the peanut-allergic or nonallergic siblings, with the exception of 1 peanut-allergic subject who demonstrated a significant increase of TCR-Vbeta11(+) cells (0.3%-5.9% of the total CD3(+) cells). However, gene scanning revealed predominant single-size PCR products for TCRBV11 in all peanut-allergic subjects after peanut stimulation. TCRBV11 polyclo-nality was observed in allergic and nonallergic subjects before peanut stimulation and in nonallergic subjects after peanut stimulation. In comparison, all subjects, before and after stimulation with peanut, showed polyclonality for TCRBV2.


CONCLUSIONS
Our results argue for clonal or oligoclonal TCRs to crude peanut and indicate that changes in the TCRBV11 subpopulation are restricted to peanut-allergic subjects after stimulation with crude peanut allergen.
Bakakos
P
P
Respiratory Cell and Molecular Biology Research Division, School of Medicine, University of Southampton, Southampton SO16 6YD, UK.
Smith
J L
JL
Warner
J O
JO
Vance
G
G
Moss
C T
CT
Hodges
E
E
Lanham
S
S
Howell
W M
WM
D000485:Allergens / Q000276:immunology*; D010367:Arachis / Q000276:immunology*; D017252:CD3 Complex / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D002999:Clone Cells; D005260:Female; D005434:Flow Cytometry; D005512:Food Hypersensitivity / Q000209:etiology*; D019674:Genes, T-Cell Receptor beta; D006801:Humans; D008213:Lymphocyte Activation; D008297:Male; D009679:Nuclear Family; D016133:Polymerase Chain Reaction; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics / Q000378:metabolism*; D013601:T-Lymphocytes / Q000276:immunology*
D000485:Allergens; D017252:CD3 Complex; D016693:Receptors, Antigen, T-Cell, alpha-beta