Dust of green coffee beans is known to be a relevant cause for occupational respiratory disorders. There is evidence for type I-sensitization as the underlying pathomechanism. Up to now no single coffee allergen has been described on molecular level. Identification of coffee allergens is warranted for standardization of allergological diagnostics.
From 17 coffee industry workers complaining about work-related rhinitis, conjunctivitis, and airway obstruction during exposure to coffee dust we obtained sera for IgE immunodetection. The participants were all male and had an average age of 40 years. A Coffea arabica pJuFo cDNA phage display library was created and screened for IgE binding to coffee proteins with 2 sera with sensitization to green coffee beans detected by ImmunoCAP (Phadia, Freiburg, Germany). By sequence analysis, a new coffee allergen (Cof a 1) was identified, expressed in E. coli, and evaluated by Western blots. The frequency of sensitization was investigated by ELISA (Enzyme-linked Immunosorbent Assay) screening.
The cDNA encoding Cof a 1 was identified as a 32 kDa Coffea arabica class III chitinase. Serum IgE antibodies to recombinant Cof a 1 were found in 3 out of 17 symptomatic coffee workers (18 %), whereas only 2 of them reacted to the commercial specific IgE test to green coffee beans (k70, Phadia). After submitting the present data, Cof a 1 has been assigned by the WHO/IUIS Allergen Nomenclature Sub-Committee.
A class III chitinase of Coffea arabica Cof a 1 was identified as an important coffee allergen. It may have a relevant potential for diagnostics of green coffee-induced respiratory disorders.