La lectine de l'arachide

Plant lectins or phyto-agglutinins are proteins that specifically recognize the glycan chains on the cell surface. Lectins from the Leguminosae (Fabaceae) have been classified in different groups according to the simple sugars they recognize. Two main groups have been identified: the galactose-specific lectins (peanut lectin [PNA], soybean lectin [SBA]) and the mannose-specific lectins (green pea lectin [PSA], lentil lectin [LCA]). Peanut lectin, a seed storage protein localized in the peanut's protein bodies, has been identified as a minor peanut allergen. As a consequence of its galactose-binding specificity, it has been used successfully to isolate T lymphocytes. Sera from the majority of peanut-allergic patients react with PNA and they also react with the closely-related lectins PSA and LCA; they interact weakly with SBA and PHA lectins. IgE-binding epitopes have been identified on the molecular surface of PNA. A few of these epitopes are structurally-related to those of PSA and LCA, which could account for the observed IgE-binding cross-reactivity between PNA and other legume lectins.