Characterization of IgE-binding epitopes of peanut (Arachis hypogaea) PNA lectin allergen cross-reacting with other structurally related legume lectins.

Sera from peanut allergic patients contain IgE that specifically interact with the peanut lectin PNA and other closely related legume lectins like LcA from lentil, PsA from pea and PHA from kidney bean. The IgE-binding activity of PNA and legume lectins was assessed by immunoblotting, surface plasmon resonance (SPR) and ELISA measurements, using sera from peanut allergic patients as a IgE source. This IgE-binding cross-reactivity most probably depends on the occurrence of structurally related epitopes that have been identified on the molecular surface of PNA and other legume lectins. These epitopes definitely differ from those responsible for the allergenicity of the major allergens Ara h 1, Ara h 2 and Ara h 3, also recognized by the IgE-containing sera of peanut allergic patients. Peanut lectin PNA and other legume lectins have been characterized as potential allergens for patients allergic to edible legume seeds. However, the clinical significance of the lectin-IgE interaction has to be addressed.