Peanut-lupine antibody cross-reactivity is not associated to cross-allergenicity in peanut-sensitized mouse strains

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Background Peanut hypersensitivity is one of the most common food allergies and one of the most common causes of death by food anaphylaxis in children and adults. Cross-reactivity of peanut-specific antibody (Ab) with other legumes is frequently demonstrated but it still remains to be demonstrated whether these responses could lead to clinical signs of cross-allergenicity. Objective We sought to evaluate peanut-specific serum IgE and IgG1 antibody (Ab) responses and anaphylactic reaction in mice strains and to assess both cross-reactivity and cross-allergenicity of peanut and lupine. Methods Four mice strains (i.e., C3H, BALB/c, CBA and SJL) were sensitized to peanut by intraperitoneal (ip) injection of crude peanut protein extract with alum. Other groups were given oral peanut extract without adjuvant. Peanut-specific antibodies (Abs) and anaphylactic responses to peanut challenge were examined. Results The C3H, CBA (H-2 k) and BALB/c (H2- d) mice exhibited high levels of peanut-specific serum IgE, IgG1 Ab responses after the intra-peritoneal sensitization. Only the two strains of mice in the H-2 k background developed anaphylactic symptoms upon intra-peritoneal challenge with crude peanut protein extract. While cross-reactivity of peanut and lupine was confirmed by ELISA, no clinical symptom of cross-allergenicity was seen after challenge with lupine. Mice that were given oral peanut showed only increase in peanut-specific IgG2a, but no IgE or IgG1 Abs and failed to develop anaphylactic reactions following injection of either peanut or lupine protein. Conclusion These results show that mice of different genetic backgrounds can be sensitized to peanut by ip injection to develop anti-peanut Abs that cross react with lupine. In addition, cross-allergenicity may not directly correlate with the presence of cross-reactive Abs since no clinical symptoms of cross-allergenicity was seen after ip challenge with lupine.