Cross-allergic reactions to legumes in lupin and fenugreek-sensitized mice.

Several legumes may induce allergy, and there is extensive serological cross-reactivity among legumes. This cross-reactivity has traditionally been regarded to have limited clinical relevance. However, the introduction of novel legumes to Western countries may have changed this pattern, and in some studies cross-allergy to lupin has been reported in more than 60% of peanut-allergic patients. We wanted to explore cross-reactions among legumes using two newly established mouse models of food allergy. Mice were immunized perorally with fenugreek or lupin with cholera toxin as adjuvant. The mice were challenged with high doses of fenugreek, lupin, peanut or soy, and signs of anaphylactic reactions were observed. Cross-allergic mechanisms were investigated using serum mouse mast cell protease-1 (MMCP-1), antibody responses, immunoblotting and ex vivo production of cytokines by spleen cells. Signs of cross-allergy were observed for all the tested legumes in both models. The cross-allergic symptoms were milder and affected fewer mice than the primary allergic responses. The cross-allergy was reflected to a certain extent in the antibody and T-cell responses, but not in serum MMCP-1 levels. Cross-allergy to peanut, soy, fenugreek and lupin was observed in lupin-sensitized and fenugreek-sensitized mice. Differences in serological responses between primary allergy and cross-allergy might be due to mediation through different immune mechanisms or reflect different epitope affinity to IgE. These differences need to be further investigated.