Quoi de neuf dans la description des allergènes de l'arachide et des fruits à coque ? New insights about the structure-function relationship of peanut and tree nut allergens

The three-dimensional structures available for peanut and tree nut allergens are derived primarily from homology modeling and, less often, from crystallographic or H-NMR studies. They belong to different groups of proteins, including: (1): legumin and vicilin proteins with a cupin motif (Ara h 1, Ara h 3/4, tree nut legumins and vicilins); (2): 2S albumins (Ara h 2, Ara h 6, Ara h 7, 2S albumins from tree nuts); (3): profilins (Ara h 5); (4): PR-10 proteins (Ara h 8); (5): lipid transfer proteins (LTP) (Ara h 9); and (6): lectins (Ara h agglutinin or peanut agglutinin [PNA]). They consist essentially of seed storage proteins occurring in protein bodies, which usually resist heat denaturation while resistance to digestive proteolysis is variable but often elevated. In addition, oleosins, which occur in seed oil bodies (oleosomes), have been recently characterized as major allergens. Most of the sequential IgE-binding epitopes (B epitopes) on the molecular surface of the major peanut allergens (Ara h 1, Ara h 2, Ara h 3) have been mapped. The existence of common epitopes is the basis for cross-reactions between peanut and tree nut, the clinical significance of which is not always evident. To date, however, very few data are available on the T-cell epitopes of peanut allergens, with the exception of the Tcell epitopes of Ara h 2 which have been characterized. These advances on the localization of the B and T-cell epitopes on the molecular surface of these allergens pave the way for the production of recombinant hypoallergenic proteins to be used in specific immunotherapy. # 2009 Elsevier Masson SAS. All rights reserved.