In vitro and in vivo cross-reactivity studies of legume allergy in a Mediterranean population.

BACKGROUND Legume allergy, mainly to lentils and chickpeas, is the fifth most common cause of food allergy in Spanish children. Serological cross-reactivity among legumes is frequent, but its clinical relevance is controversial. The aim of this study was to investigate the cross-reactivity among lentils, chickpeas, peas, white beans and peanuts and its clinical relevance in pediatric patients. METHODS Fifty-four children with clinical allergy to legumes were included. Cross-reactivity was evaluated by ELISA inhibition experiments and oral food challenges to legumes. SDS-PAGE immunoblots were conducted with raw and boiled legume extracts. RESULTS ELISA inhibition experiments demonstrated more than 80% inhibition with lentil, chickpea and pea extracts. Immunoblots performed with raw legume extracts (lentil, chickpea and pea) and individual sera revealed that more than 50% of the sera identified an allergen with approximately 50 kDa in all three legume extracts. In all three boiled extracts an intense band at approximately 50 kDa was visualized using a serum pool. The oral legume challenges demonstrated that 37 children (69%) were allergic to 2 or more legumes (median 3 legumes). The most frequent associations were allergy to lentils and chickpeas (57%), allergy to lentils and peas (54%) and allergy to lentils, chickpeas and peas (43%). CONCLUSIONS In vitro inhibition experiments demonstrated a high degree of cross-reactivity among lentils, chickpeas and peas. Food challenges confirmed that clinical allergy to all three legumes is frequent in our cohort of Spanish children.