title: Identification of amino acids critical for IgE-binding to sequential epitopes of bovine kappa-casein and the similarity of these epitopes to the corresponding human kappa-casein sequence.
abstract: BACKGROUND
  The delineation of allergenic (i.e. IgE-binding) epitopes in cow's milk proteins and the amino acids (AAs) critical for IgE-binding is necessary to understand better the structural properties of an allergen and to develop more efficacious immunotherapeutic reagents. Furthermore, this information may enable us to understand better cross-sensitivity between different allergens.
  
  
  METHODS
  Eleven peptides, 10-14 AAs in length, representing the IgE-binding epitopes of kappa-casein were synthesized on a derivatized cellulose membrane with single AA substitutions at each position. Membranes were incubated with pooled sera from 15 milk-allergic patients and individual sera from 10 of the patients included in the pool.
  
  
  RESULTS
  For 10/11 allergenic peptides, one to five different single AA substitutions resulted in elimination of IgE-binding of pooled patient sera. Overall at least one mutated peptide could be found for these 10 IgE-binding sites that resulted in a reduction of IgE-binding in at least 80% of the patients who recognized the native protein. Furthermore, the IgE-binding region at AA104-112 on bovine kappa-casein showed a high degree of similarity with the human kappa-casein, respectively, including the AAs critical for IgE-binding.
  
  
  CONCLUSIONS
  This finding suggests that critical AAs should be assessed with both pooled and individual patient sera to account for the B-cell epitope heterogeneity between patients, with cow's milk allergy. In addition, we identified two potentially cross-reactive peptides between bovine and human caseins of unknown clinical relevance.
authors.affiliation: Division of Pediatric Allergy & Immunology, Jaffe Institute for Food Allergy, The Mount Sinai School of Medicine, New York, NY 10029-6574, USA.
authors.forename: N
authors.initials: N
authors.lastname: Han
authors.forename: K M
authors.initials: KM
authors.lastname: Järvinen
authors.forename: R R
authors.initials: RR
authors.lastname: Cocco
authors.forename: P J
authors.initials: PJ
authors.lastname: Busse
authors.forename: H A
authors.initials: HA
authors.lastname: Sampson
authors.forename: K
authors.initials: K
authors.lastname: Beyer
mesh_terms: D000293:Adolescent; D000595:Amino Acid Sequence; D000818:Animals; D002364:Caseins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D000939:Epitopes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000378:metabolism*; D016269:Milk Hypersensitivity / Q000209:etiology* / Q000276:immunology; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism
chemical_list: D002364:Caseins; D000939:Epitopes; D010455:Peptides; D007073:Immunoglobulin E