title: Identification of unique peanut and soy allergens in sera adsorbed with cross-reacting antibodies.
abstract: BACKGROUND
  Soybean and peanut are members of the legume family and share several common antigenic fractions. Patients allergic to one of these foods have serum IgE antibodies that immunologically cross-react with other legumes. Nevertheless, ingestion of other legumes generally does not induce an allergic reaction, suggesting that cross-reacting antibodies are not clinically relevant.
  
  
  OBJECTIVE
  This study was designed to identify unique peanut or soybean antigenic fractions, with sera adsorbed to remove cross-reacting antibodies, thus resulting in sera with IgE antibodies unique to either soy or peanut.
  
  
  METHODS
  Cross-reacting antibodies to soy were removed from the sera of two patients allergic to peanut and soy and three patients allergic to peanut by soy-affinity chromatography. Cross-reacting antibodies to peanut were adsorbed from the sera of a patient allergic to peanut and soy and a patient allergic to peanut by peanut-affinity chromatography. Adequate removal of cross-reacting antibodies was verified by ELISA after each adsorption step. Unadsorbed sera and sera adsorbed to remove cross-reacting antibodies (either to soy or to peanut) were assayed for specific IgE binding to peanut or soy immunoblots.
  
  
  RESULTS
  Unique peanut-specific IgE antibodies (i.e., soy antibody-adsorbed) were found to bind to peanut fractions at 46, 29, 25, 19, 17, 14, and 5 kd on immunoblots of whole peanut protein. Similarly, unique soy-specific IgE (i.e., peanut antibody-adsorbed) were found to bind a fraction at 46 kd, and to a lesser extent, to a fraction at 21 kd on immunoblots of whole soy protein. The 73% reduction of IgE antibody binding to peanut by ELISA after adsorption of cross-reacting antibodies indicates extensive cross-reactivity between soy and peanut antigens.
  
  
  CONCLUSIONS
  Antigen-affinity chromatography is an effective method for removal of cross-reacting antibodies. We identified IgE antibody binding (with sera where cross-reacting antibodies were removed) to several unique antigenic fractions of peanut and soy. Further studies will determine the clinical significance of these fractions in IgE-mediated food hypersensitivity reactions.
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: P A
authors.initials: PA
authors.lastname: Eigenmann
authors.forename: A W
authors.initials: AW
authors.lastname: Burks
authors.forename: G A
authors.initials: GA
authors.lastname: Bannon
authors.forename: H A
authors.initials: HA
authors.lastname: Sampson
mesh_terms: D000327:Adsorption; D000485:Allergens / Q000276:immunology / Q000302:isolation & purification*; D010367:Arachis / Q000276:immunology*; D002846:Chromatography, Affinity; D003429:Cross Reactions; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D007887:Fabaceae / Q000276:immunology; D005512:Food Hypersensitivity / Q000097:blood / Q000276:immunology*; D006801:Humans; D007106:Immune Sera / Q000276:immunology*; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology / Q000302:isolation & purification*; D010936:Plant Extracts / Q000276:immunology; D010940:Plant Proteins / Q000097:blood / Q000276:immunology / Q000302:isolation & purification*; D010946:Plants, Medicinal; D013025:Glycine max / Q000276:immunology*
chemical_list: D000485:Allergens; D007106:Immune Sera; D010936:Plant Extracts; D010940:Plant Proteins; D007073:Immunoglobulin E