Cof a 1: identification, expression and immunoreactivity of the first coffee allergen

Int Arch Allergy Immunol. 2012;159(3):235-42. doi: 10.1159/000337461. Epub 2012 Jun 20.


Background: Over the past years, dust of green coffee beans has become known to be a relevant cause for occupational type I allergies. Up to now, allergy diagnostics is based on native green coffee bean extract which exhibits insufficient specificity due to interfering substances as well as batch-to-batch variations. No coffee allergen has been described on the molecular level so far. The aim of this study was to identify the first allergen of green coffee.

Methods: The allergenicity of native green coffee bean extracts was analyzed by means of ImmunoCAP in sera of 17 symptomatic coffee workers. A Coffea arabica pJuFo cDNA phage display library was constructed and screened for IgE binding to coffee proteins with 2 sera from allergic coffee workers. By sequence analysis, a new coffee allergen (Cof a 1) was identified, expressed in Escherichia coli, and evaluated by Western blots. The frequency of sensitization was investigated by ELISA screening.

Results: The Cof a 1 cDNA encoded a 32-kDa C. arabica class III chitinase. Serum IgE antibodies to the recombinant allergen were found in 3 out of 17 symptomatic coffee workers (18%), whereas only 2 of them reacted to the commercial allergy test.

Conclusions: A class III chitinase of C. arabica was identified to be the first known coffee allergen Cof a 1. It may have a relevant potential for the specific diagnosis of coffee sensitization.

MeSH terms

  • Adult
  • Allergens / chemistry
  • Allergens / genetics
  • Allergens / immunology*
  • Amino Acid Sequence
  • Base Sequence
  • Cell Surface Display Techniques
  • Chitinases / chemistry
  • Chitinases / genetics
  • Chitinases / immunology*
  • Cloning, Molecular
  • Coffea / adverse effects
  • Coffea / immunology*
  • Dust / immunology*
  • Enzyme-Linked Immunosorbent Assay
  • Escherichia coli / genetics
  • Gene Expression
  • Gene Library
  • Humans
  • Immunoglobulin E / blood
  • Immunoglobulin E / immunology
  • Male
  • Middle Aged
  • Molecular Sequence Data
  • Occupational Diseases / blood
  • Occupational Diseases / etiology
  • Occupational Diseases / immunology*
  • Plant Proteins / chemistry
  • Plant Proteins / genetics
  • Plant Proteins / immunology*
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / immunology
  • Respiratory Hypersensitivity / blood
  • Respiratory Hypersensitivity / etiology
  • Respiratory Hypersensitivity / immunology*


  • Allergens
  • Dust
  • Plant Proteins
  • Recombinant Proteins
  • Immunoglobulin E
  • Chitinases
  • chitinase, class III