Fungal Allergen Extracts

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.

Global Warming and Allergies

“Global warming”, also referred as to “climate change”, is a subject that has received major attention during the past years. The concept of global warming popularly used now refers to a gradual raise in the global ambient temperature that began in the 19th century, parallel with an increase in levels of air pollutants resulting from human activities, associated with industrialization and the use of fossil fuels. Climate change refers to climatic alterations over extended periods, often millennia.

While the real occurrence of global warming has been debated, the Intergovernmental Panel on Climate Change prepared an extensive report, which supports that global warming is occurring. Direct data indicates an increase in the levels of atmospheric CO2 parallel with an increase of the global surface temperature over time. Changes in rainfall patterns have accompanied the detected temperature increase.

Climate change has been reported to affect ecosystems. Warmer temperatures have altered the geographical distribution of many plant species and their pollination patterns. For example, ragweed pollinates earlier now than in the past and produces larger quantities of pollen in urban vs rural areas. Indirect evidence suggests that allergic individuals could suffer more severe and frequent exacerbations of the disease in the future.

While the proposition that global warming could indirectly affect allergic individuals has gained a lot of media attention, this hypothesis needs to be evaluated by conducting long-term epidemiological studies, which should include the analysis of potential confounding factors. The potential connection between global warming and allergies should be an area of research involving multi-discipline groups.


Natural or Recombinant Allergens

Allergenic materials are used to prepare allergen extracts to diagnose and treat allergic patients. Natural materials have been used for this purpose for many years. 

It is often difficult to obtain sufficient quantities of natural allergenic products. In addition, the safety of those materials is questioned, particularly in Europe, where regulatory entities have proposed guidelines to monitor the quality of these products.

A different perspective regarding natural allergenic products exists in the United States of America (USA). Currently, the Food and Drug Administration in the USA only demands that the quality and safety of the final allergen extracts be assessed. This organization has not yet focused on assessing the quality of the products used to prepare the associated extracts.

Recombinant allergens are alternatives to circumvent the caveats of using natural allergenic materials. While the science of obtaining recombinant allergens is rapidly evolving, natural products most likely will continue to be used for many years to come because of the varying limitations regarding the production and use of recombinant allergens.  For example, it is currently not possible to obtain recombinant forms of all clinically relevant allergens. In addition, the safety and efficacy of such allergens need to be properly documented through appropriate clinical trials, which takes time to complete and is extremely expensive.

We are in a transition period.  Meanwhile, the perspectives regarding the use of natural allergenic products to prepare allergen extracts in the USA and Europe should be harmonized.