RATIONALE: It is well known that some individuals with certain food allergy demonstrate cross-reactive allergy to other foods, while others do not. We wanted to identify homologues of the major peanut allergens, Ara h1, Ara h2 and Ara h3, in other legumes and characterize cross-reactivity among these using specific polyclonal antibodies and serum IgE from allergic individuals.METHODS: Protein was extracted from raw and roasted peanut (PN), chickpea (CP), split green pea (SP), lentil (L), black bean (BB) and soy (S). These proteins were subjected to Western blot analysis using (1) purified antibodies to Ara h1, Ara h2, or Ara h3; and (2) serum from patients with a known clinical allergy to peanut and soy.RESULTS: Our anti-Ara h1, 2, and 3 antibodies bound to each Ara h1, 2 and 3 with very high specificity. These antibodies also bound to very specific proteins, with various intensities in CP, SP, L and S, identifying the presence of sequentially homologous proteins of various sizes. Additionally, binding was seen to some, but not all of these proteins on membranes incubated with serum of allergic individuals.CONCLUSIONS: Proteins were found in selected legumes that are homologous to various degrees to the major allergens in peanut. Some previously undefined homologues are recognized by either or both polyclonal antibodies and human IgE. It is possible that in the future, polyclonal antibodies against major allergens may assist in (1) identifying cross-reactive proteins in foods (including novel foods) and (2) deciphering the differences between clinical and non-clinical allergic cross-reactivity. RATIONALE: It is well known that some individuals with certain food allergy demonstrate cross-reactive allergy to other foods, while others do not. We wanted to identify homologues of the major peanut allergens, Ara h1, Ara h2 and Ara h3, in other legumes and characterize cross-reactivity among these using specific polyclonal antibodies and serum IgE from allergic individuals. METHODS: Protein was extracted from raw and roasted peanut (PN), chickpea (CP), split green pea (SP), lentil (L), black bean (BB) and soy (S). These proteins were subjected to Western blot analysis using (1) purified antibodies to Ara h1, Ara h2, or Ara h3; and (2) serum from patients with a known clinical allergy to peanut and soy. RESULTS: Our anti-Ara h1, 2, and 3 antibodies bound to each Ara h1, 2 and 3 with very high specificity. These antibodies also bound to very specific proteins, with various intensities in CP, SP, L and S, identifying the presence of sequentially homologous proteins of various sizes. Additionally, binding was seen to some, but not all of these proteins on membranes incubated with serum of allergic individuals. CONCLUSIONS: Proteins were found in selected legumes that are homologous to various degrees to the major allergens in peanut. Some previously undefined homologues are recognized by either or both polyclonal antibodies and human IgE. It is possible that in the future, polyclonal antibodies against major allergens may assist in (1) identifying cross-reactive proteins in foods (including novel foods) and (2) deciphering the differences between clinical and non-clinical allergic cross-reactivity.