Production profile of the major allergen Alt a 1 in Alternaria alternata cultures.

Background: The fungus Alternaria is strongly associated with asthma, but the importance of fungal allergen products is frequently underestimated. The profile of allergen release from fungal material is poorly understood.

Objective: To investigate expression of the major allergen of Alternaria alternata, Alt a 1, during its growth in culture conditions for allergen extract production.

Methods: Allergen expression was examined by Alt a 1-specific 2-site monoclonal antibody enzyme-linked immunosorbent assay, immunoblotting, and potency assays. The release of Alt a 1 was studied by transmission electron microscopy in conjunction with immunogold staining by using antibodies with specificity for Alt a 1.

Results: A maximum amount of Alt a 1 was obtained after 4.5 weeks of growing, and it was found predominantly in the spent culture medium. In the same way, total IgE binding activity showed 15-fold more activity in the spent culture medium than in the buffer-extractable antigen fraction. Immunogold electron microscopy provided evidence that Alt a 1 is released from spores and mycelia.

Conclusions: Alternaria alternata allergenic proteins were constantly released into the culture medium, where they accumulated. Alt a 1 was a good marker for checking optimal culture conditions for A alternata extract production intended for clinical use.