Occupational allergy to Aspergillus niger-derived phytase in the animal feed industry

G. Dockes, N. Kamminga, L. Helwegen, i.j. Spithoven, D.J.J. Heederik.


Modern biotechnology has considerably increased the number of different microbial enzymes used in e.g. the food and feed industry. Since many enzymes are potent type I allergens, new examples of atopic sensitization and symptomatic allergy may be expected, particularly in occupational populations. This study was performed in an experimental animal feed production plant evaluating the use of phytase, a phosphatase produced from a modified strain of Aspergillus niger, and was inititiated by the case of a worker who developed severe respiratory symptoms during enzyme application. A sample of 11 workers who directly worked with the enzyme, and 11 'internal controls' - mainly office workers - from the same plant 4 answered a questionnaire on allergic and respiratory symptoms, and provided blood samples for lgE analysis. IgE enzyme immunoassays (EIA) with extracts of the solid or liquid enzyme preparations as used in the plant revealed specific lgE sensitisation in 10 and 9 of the 11 'exposed' workers, respectively, particularly in those with respiratory complaints. In the 'internal control' group these figures were 5 and 3, respectively, and reactivity of positive sera was significantly less than in the 'exposed' group. Only 3 weakly positive reactions were noted in 19 atopic and non-atopic 'external' controls. In lgE immunoblotting the IgE appeared to react with the major protein in the preparations, presumably the active phytase. Although positive lgE reactions were also found with another - commercially available - A. niger phytase, the workers' lgE antibodies showed much stronger reactions with the phytase preparations used in the plant. Cross-reactivity was also found with extracts of A. niger, but not with other Aspergillus or Penicillium species.The results thus confirm that introduction of a new enzymes for industrial use may confer new risks of occupational type I allergy.

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7th European Respiratory Society Annual Conference
    • ERS 17th (2007)