Delineation of PLA2 epitopes using short or long overlapping synthetic peptides: interest for specific immunotherapy.
BACKGROUND
Venom immunotherapy is definitely indicated in severe systemic anaphylactic reactions to bee stings, but is not devoided of risks of anaphylaxis. Safer methods of immunotherapy need to be developed.


OBJECTIVE
To delineate phospholipase A2 T-cell epitopes using short 15mer vs long 40-60mer overlapping peptides, and to approach the potential interest of a venom immunotherapy based on the use of long peptides (1-60, 51-99, 90-134) mapping the whole phospholipase A2 molecule vs a restricted number of immunodominant epitopes.


METHODS
Proliferation of a CD8+ T cell depleted peripheral blood mononuclear cell fraction and short-term T-cell lines from unselected bee venom hypersensitive patients in response to phospholipase A2 synthetic peptides.


RESULTS
Whereas T-cell proliferation to 15mer overlapping peptides was weak, T-cell response to long overlapping peptides was in contrast vigorous in all patients, mostly directed to C-terminal peptide 90-134. Our results did not support the concept of rare dominant T-cell epitopes, and disclosed T-cell responses to multiple epitopes in several patients. No significant IgE-binding to long overlapping peptides was detected except in one patient against peptide 90-134.


CONCLUSIONS
15mer peptides might not be sensitive enough to fully delineate all potential T-cell epitopes scattered along the allergen. Since they do not bind IgE in vitro or only weakly, and taking into account a T-cell response frequently directed to multiple epitopes, long overlapping peptides may represent ideal tools for immunotherapy.
Division of Immunology and Allergy, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
R
R
Kämmerer
A
A
Kettner
Y
Y
Chvatchko
N
N
Dufour
J M
JM
Tiercy
G
G
Corradin
F
F
Spertini
D001514:Bee Venoms / Q000276:immunology*; D002460:Cell Line; D003888:Desensitization, Immunologic; D018604:Epitope Mapping; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000628:therapy*; D015151:Immunoblotting; D007073:Immunoglobulin E / Q000378:metabolism; D007963:Leukocytes, Mononuclear; D010455:Peptides / Q000276:immunology; D010741:Phospholipases A / Q000276:immunology*; D054467:Phospholipases A2; D013601:T-Lymphocytes / Q000276:immunology
D001514:Bee Venoms; D018984:Epitopes, T-Lymphocyte; D010455:Peptides; D007073:Immunoglobulin E; D010741:Phospholipases A; D054467:Phospholipases A2