Differentiated Patterns of Legume Sensitisation in Peanut-Allergic Patients

Patients with peanut allergy are often serologically sensitised to other legumes. If primary peanut allergy was contracted, secondary allergies to other legume plants may develop. The cross-sensitisation implies an enhanced risk of food-related anaphylaxis for the patients even if its clinical relevance is under discussion. In the present study, 32 patients with anti-peanut immunoglobulin E-levels (IgE) of at least class 1 according to the immunoCap (TM) classification system were included. The patients had been referred to the Norwegian National Register and Reporting System for Severe Allergic Reactions to Food with histories of anaphylaxis by the consumption of legume-containing foods. The patient sera were analysed for IgE that reacted to peanut (Arachis hypogea), soybean (Glycine max), pea (Pisum sativum), lupin (Lupinus albus) and fenugreek (Trigonella foenum graecum). Immunoblot experiments were performed using extracts of in total eight different legume plants. IgE measurements and blot analyses revealed differentiated patterns of legume sensitisation. One third of the patients had anti-peanut IgE class 4 to 6. In contrast, just one patient had specific IgE higher than class 4 to respectively pea, soybean and fenugreek. However, ten patients had elevated anti-fenugreek IgE (>= class 3), significantly more than for the other legumes. The second highest levels were found for soybean, followed by pea and lupin. The immunoblots showed particularly strong IgE binding to proteins at 12, 22, 30, 36 and 50 kDa for all legumes, indicating that the major peanut allergens Ara h 1, Ara h 2 and Ara h 3 are strong candidates for causing cross-sensitivity.