A large number of fungal allergen extracts for diagnosis and treatment of allergic diseases are available on the market. This can be confusing for the allergist/immunologist to properly select the most clinically relevant extracts.
While the proper selection of the appropriate extracts derived from particular genera and/or species is critical, other factors regarding the materials used to obtain those extracts also play a pivotal role responsible for the quality and consistency of fungal extracts. It is essential for the allergist/immunologist to properly understand those factors because they are ultimately responsible for a large variation in allergen content and potency among extracts of the same species produced by different manufacturers.
Fungi have a high level of genetic adaptability to the environment. They often mutate as a result of external stimuli. Those mutations and the direct effect of environmental conditions are associated with selective allergen production and the potential secretion of secondary metabolites, particularly mycotoxins and polysaccharides. Therefore, when fungi are cultured to manufacture allergen extracts, those factors must be controlled.
For the purpose of manufacturing allergen extracts, the fungal strains used in cultures should be obtained from accredited sources such as the American Type Culture Collection or the Centraalbureau voor Schimmelcultures. The selected strains must be grown under very strict conditions in compliance with specific regulations and general manufacturing guidelines.
The environmental factors responsible for fungal allergen production are many. The most relevant are the specific media formulations and culture conditions used to grow fungi. They are considered intellectual property that belongs to the allergen manufacturing companies that obtain fungal extracts.
While materials derived from animals or plants are generally used to prepare laboratory culture media, they can potentially be allergenic and/or contain pathogenic microorganisms. Therefore, the media used to grow fungi must be carefully formulated to assure its safety.
The common culture conditions are static or under agitation. These conditions are responsible for the amount of oxygen available in the cultures, which affects the types and levels of allergens and secondary metabolites produced.
Once fungal cultures achieve a particular level of maturity, they are harvested and inactivated to assure that no live fungi are present in the materials. Proof on inactivation is required before further processing can be initiated.
The fungal materials used for the production of allergen extracts vary, depending on particular suppliers. Mycelia, culture filtrates, or both can be used to prepare allergen extracts.
Fungal allergen extracts should be obtained from one single reliable supplier. The allergist/immunologist should be aware of the fact that extracts derived from the same genera and species produced by different manufactures are not equivalent in terms of allergen content and potency.