Evaluation of pollen purity to prepare allergen extracts

Several factors are responsible for the composition, consistency, and stability of the allergen extracts used to diagnose and treat allergic diseases. The quality of the raw materials used to produce those extracts should be maximized. Proper evaluation of pollen purity to prepare allergen extracts is critical to assure the quality of the final product.

Pollen is a unique raw material because is exposed to the outdoor environment before and during collection. Therefore, pollen can be potentially impacted by airborne components present outdoors. They include both ubiquitous biological and chemical contaminants. The potential impact of chemical contaminants in pollen is not discussed in this post.

The biological components that typically contaminate pollen include plant parts, foreign pollen, fungal structures, and other biological agents. The pollen collected for the production of allergen extracts must meet particular purity specifications.

Specifications for the maximum allowed concentrations of biological contaminants in pollen are typically internally proposed by allergen manufacturing companies based on the likelihood of achieving a particular purity level after cleaning pollen. These specifications are not based on any potential health effects upon exposure to the contaminants because those effects are unknown.

The presence of biological contaminants in pollen is impossible to avoid, difficult to evaluate, and the interpretation of the associated purity data is very subjective.  However, if the evaluation of pollen purity to prepare allergen extracts is properly performed and interpreted, it can benefit the allergen manufacturing companies that produce such extracts.

For example, the presence of a variety of fungal spores, foreign pollen grains, and plant parts in pollen should be expected, and it simply indicates insufficient cleaning. This pollen can be further cleaned and used to produce allergen extracts.

To the contrary, the presence of large amounts of one single spore type, hyphae or sporulating structures indicates that fungi have actively colonized polled due to current or past excessive moisture. Thus, this pollen should be discarded.

The image below describes our proposal to prepare a guidance document to assist the individuals and organizations involved in the evaluation of pollen purity to prepare allergen extracts. Please click the image to see it enlarged.  

Posted in Allergen extracts for pharmaceutical applications.