title: Identification of two metallothioneins as novel inhalative coffee allergens cof a 2 and cof a 3.
abstract: BACKGROUND
  Dust of green coffee beans is known to be a relevant cause for occupational allergic disorders in coffee industry workers. Recently, we described the first coffee allergen (Cof a 1) establishing an allergenic potential of green coffee dust.
  
  
  OBJECTIVE
  Our aim was to identify allergenic components of green coffee in order to enhance inhalative coffee allergy diagnosis.
  
  
  METHODS
  A Coffea arabica pJuFo cDNA phage display library was created and screened for IgE binding with sera from allergic coffee workers. Two further coffee allergens were identified by sequence analysis, expressed in E. coli, and evaluated by Western blots. The prevalence of sensitization to recombinant Cof a 1, Cof a 2, and Cof a 3 and to commercially available extract was investigated by ELISA (enzyme-linked immunosorbent assay) respectively CAP (capacity test) screening in 18 sera of symptomatic coffee workers.
  
  
  RESULTS
  In addition to the previously described chitinase Cof a 1, two Coffea arabica cysteine-rich metallothioneins of 9 and 7 kDa were identified and included in the IUIS Allergen Nomenclature as Cof a 2 and Cof a 3. Serum IgE antibodies to at least one of the recombinant allergens were found in 8 out of 18 symptomatic coffee workers (44%). Only 2 of the analysed sera (11%) had reacted previously to the commercial allergy test.
  
  
  CONCLUSIONS
  In addition to the previously described Cof a 1 we have identified two further coffee proteins to be type I coffee allergens (Cof a 2 and Cof a 3) which may have a relevant potential for the specific diagnosis and/or therapy of coffee allergy.
authors.affiliation: Biocenter Klein Flottbek and Botanical Garden, University of Hamburg, Hamburg, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Peters
authors.affiliation: Biocenter Klein Flottbek and Botanical Garden, University of Hamburg, Hamburg, Germany.
authors.forename: Karsten
authors.initials: K
authors.lastname: Frenzel
authors.affiliation: Biocenter Klein Flottbek and Botanical Garden, University of Hamburg, Hamburg, Germany.
authors.forename: Reinhold
authors.initials: R
authors.lastname: Brettschneider
authors.affiliation: Institute for Occupational Medicine and Maritime Medicine (ZfAM), University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Marcus
authors.initials: M
authors.lastname: Oldenburg
authors.affiliation: Institute for Occupational Medicine and Maritime Medicine (ZfAM), University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Cordula
authors.initials: C
authors.lastname: Bittner
mesh_terms: D000328:Adult; D000485:Allergens / Q000276:immunology*; D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D040503:Coffea / Q000009:adverse effects* / Q000235:genetics; D003069:Coffee / Q000009:adverse effects*; D018076:DNA, Complementary; D005260:Female; D015870:Gene Expression; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology; D008297:Male; D008668:Metallothionein / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D008875:Middle Aged; D008969:Molecular Sequence Data; D009784:Occupational Diseases / Q000276:immunology; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D011994:Recombinant Proteins; D016415:Sequence Alignment
chemical_list: D000485:Allergens; D003069:Coffee; D018076:DNA, Complementary; D010940:Plant Proteins; D011994:Recombinant Proteins; D007073:Immunoglobulin E; D008668:Metallothionein