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

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.