Cross-reactivity between peanut and lupin proteins

Peanut-allergic individuals may also react to lupin, which, for this reason, has been included in the EU list of food allergens. Since there is not yet any general consensus on the major allergen/s in lupin, the objective of this investigation was to compare the reactivity of the main lupin proteins towards the IgE of the sera of allergic patients. Both Lupinus albus and Lupinus angustifolius were investigated. ELISA's, Western blotting and mass spectrometry, including also de novo sequencing of the unknown lupin proteins, were used for identifying the IgE-binding proteins. Significant differences in the protein reactivities were observed. In particular, there was a direct relationship between the level of peanut-specific IgE's and the cross-reactivity to lupin proteins; also the reactivity of each serum appeared to be unique. Although numerous lupin proteins bind IgE's, our data suggest a predominant contribution of α-conglutin in the reactivity of both L. albus and L. angustifolius.