Characterization of the sensitization profile to lupin in peanut-allergic children and assessment of cross-reactivity risk

Background Case reports of allergy to lupin, due to primary sensitization or cross-reactions with other legumes, are increasing as a consequence of the augmented use of lupin flour in bakery, pasta formulations and other food items. The main allergens that have been associated with the sensitization to lupin are - and -conglutins and, to a lesser extent, - and -conglutin, but no conclusive data are available so far. The aim of this study was to characterize the sensitization pattern to lupin in a group of 12 Italian children allergic to peanut and identify the specific lupin proteins involved in the cross-reactivity with peanut. Methods The immunochemical cross-reactivity among peanut and lupin was evaluated by both invitro immunoblotting and invivo fresh food skin prick test (FFSPT). Results The results showed that -conglutin was recognized by cutaneous IgEs from 7/12 peanut-allergic children in FFSPT and serum IgEs from 5/12 in immunoblotting, while 4/12 and 8/12 patients tested positive to -conglutin in FFSPT and immunoblotting, respectively. No significant immunoreactive responses were observed to - and -conglutins under non-reducing conditions, but they were bound in FFSPT by the sera of 5/12 and 3/12 patients, respectively. Conclusion In this group of allergic children, -conglutin has been identified as the major lupin allergen involved both invitro and invivo cross-reactivity with peanut proteins. The role of -conglutin in the cross-reactivity between lupin and peanut proteins was also relevant and clear, despite the observed unspecificity of the immunoblotting responses.