Lupine-induced anaphylaxis

Background Legumes are one of the most common foods causing allergic reactions in children and adults. Cross-reacting antibodies are frequently demonstrated in this family but the real clinical cross-reactivity is uncommon. Objective To report a case of lupine-induced anaphylaxis and to elucidate in vivo and in vitro cross-reactivity with some legumes. Methods Skin prick test (SPT) with some legumes were performed. Cap-IgE, ELISA-IgE, and immunoblotting were carried out. Open oral challenges with some legumes were performed. Cross-reactivity was studied by ELISA and immunoblotting inhibition. Results The results demonstrated type-I hypersensitivity reactions with lupine and some other legumes. Cap-IgE with peanut was positive but the SPT and ELISA-IgE were negative and the patient tolerated a peanut challenge. ELISA inhibition revealed a partial inhibition (62%) using lupine as the solid phase. Partial inhibition was demonstrated by immunoblotting inhibition. Open oral challenge with peanut and green bean were negative but positive with pea. Conclusion We present a lupine sensitized patient with positive SPT and in vitro cross-reactivity with other legumes. Clinical cross-reactivity progressively developed over a 5-year period. Discrepancies were found between the clinical aspect and in vitro study of peanut allergy. Factors determining the wide variability in cross-reactivity among individuals are still obscure.