title: Human IgE-binding epitopes of the latex allergen Hev b 5.
abstract: BACKGROUND
  Hev b 5 is an acidic protein (isoelectric point, 3.5) rich in glutamic acid with 9 repeated amino acid (AA) sequences of XEEX or XEEEX. Although its function in Hevea brasiliensis is unknown, Hev b 5 has been identified as a major latex allergen. Immunoblot inhibition studies suggest Hev b 5 exists as multiple isoforms or contains a common epitope found in several other proteins.
  
  
  OBJECTIVE
  The purpose of this study was to further characterize Hev b 5 and to identify linear IgE-binding epitopes.
  
  
  METHODS
  Octapeptides spanning the entire Hev b 5 protein were synthesized on a derivatized cellulose membrane. The membrane was reacted with sera pooled from health care workers allergic to latex or rabbits immunized with latex proteins. B-cell epitopes were identified by subsequent incubations with the appropriate secondary antibodies and detected by using chemifluorescence.
  
  
  RESULTS
  Sera from patients allergic to latex recognized 6 IgE-binding regions located throughout the molecule. Two epitopes (2 and 4) had the common AA sequence of KTEEP. Epitopes 3 and 5 had a similar AA sequence of EEXXA, where X was P, T, or K. Epitopes 1 and 6 appeared to be unrelated to the other epitopes. Database analysis could not identify other proteins with similar sequences. Neither of the XEEEX sequences bound IgE. Control sera failed to react to any peptides.
  
  
  CONCLUSIONS
  Hev b 5 exists as multiple isoforms, but only small amounts are present in the nonammoniated latex preparations, such as those used for diagnostic tests, and this may help to explain the relatively poor sensitivity of some in vitro tests.
authors.affiliation: Laboratory of Immunobiology, Guthrie Research Institute, Sayre, PA 18840, USA.
authors.forename: D H
authors.initials: DH
authors.lastname: Beezhold
authors.forename: V L
authors.initials: VL
authors.lastname: Hickey
authors.forename: J E
authors.initials: JE
authors.lastname: Slater
authors.forename: G L
authors.initials: GL
authors.lastname: Sussman
mesh_terms: D000485:Allergens / Q000276:immunology*; D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000097:blood; D052179:Antigens, Plant; D015153:Blotting, Western; D018985:Epitopes, B-Lymphocyte; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology / Q000378:metabolism*; D007074:Immunoglobulin G / Q000276:immunology; D007840:Latex / Q000276:immunology; D008969:Molecular Sequence Data; D010940:Plant Proteins; D011817:Rabbits / Q000276:immunology
chemical_list: D000485:Allergens; D000906:Antibodies; D052179:Antigens, Plant; D018985:Epitopes, B-Lymphocyte; D007074:Immunoglobulin G; D007840:Latex; D010940:Plant Proteins; C101800:allergen Hev b 5; D007073:Immunoglobulin E