Cof a 1: identification, expression and immunoreactivity of the first coffee allergen.
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.
Biocenter Klein Flottbek and Botanical Garden, University of Hamburg, Hamburg, Germany.
Nikolay
N
Manavski
Ulrike
U
Peters
Reinhold
R
Brettschneider
Marcus
M
Oldenburg
Xaver
X
Baur
Cordula
C
Bittner
D000328:Adult; D000485:Allergens / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D000595:Amino Acid Sequence; D001483:Base Sequence; D061505:Cell Surface Display Techniques; D002688:Chitinases / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D003001:Cloning, Molecular; D040503:Coffea / Q000009:adverse effects / Q000276:immunology*; D004391:Dust / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D015723:Gene Library; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009784:Occupational Diseases / Q000097:blood / Q000209:etiology / Q000276:immunology*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D012130:Respiratory Hypersensitivity / Q000097:blood / Q000209:etiology / Q000276:immunology*
D000485:Allergens; D004391:Dust; D010940:Plant Proteins; D011994:Recombinant Proteins; D007073:Immunoglobulin E; D002688:Chitinases; C110892:chitinase, class III