Composition and stability of allergenic extracts made from gamma-irradiated rye grass (Lolium perenne) pollen

Stability of allergen extracts used in skin testing and immunotherapy

PURPOSE OF REVIEW

The present article reviews allergen extract stability applied to US manufactured products. Methods used to measure potency of extract concentrates, patient prescription dilute extracts, and mixes containing degrading enzymes will be discussed.

RECENT FINDINGS

Information about the allergen extract active ingredient components contributing to potency is increasing. Pertinent stability issues include the type of diluent used for extraction and mixing. Fifty percent glycerin greatly extends the time over which extracts remain potent, including in mixes with fungal and insect extracts known to contain protein-degrading enzymes. Diluents that contain additional protein content such as human serum albumin increase stability of dilute solutions. Many of the most rigorous studies on allergen stability have been performed by allergenic extract manufacturers in support of Food and Drug Administration approved dating for standardized products and are not published.

SUMMARY

Studies addressing how antigens in extracts change under various storage conditions have provided general guidance for expiration dating, but the diversity of extracts and testing methods have been less than complete. Additional findings that are increasing our knowledge of extract shelf life will be discussed.

Electron beam irradiation as protection against the environmental release of recombinant molecules for biomaterials applications

In biomaterials applications there exists a need to protect against the environmental release of recombinant microorganisms and transmissible genetic material and to prevent the recovery of proprietary genetic information. Irradiation technologies have long been used to eliminate microorganisms associated with spoilage and contamination and recent studies have demonstrated that moderate doses of irradiation may be used to sterilize medically important proteins without causing adverse effects in their desirable biological properties. Recombinant Escherichia coli cells expressing organophosphate hydrolase (OPH, E.C. 3.1.8.1), an important enzyme for the detection and decontamination of neurotoxic pesticides and chemical warfare agents, were subjected to electron beam irradiation to gauge its effect on enzymatic activity, cell viability and DNA recoverability. Bacterial samples were irradiated at 2, 20 and 200 kGy using a 10 MeV electron source. Irradiation levels of 2 to 20 kGy were sufficient to eliminate viable cells without affecting OPH enzymatic activity. Biologically active DNA was recovered via PCR from all samples through the 20 kGy irradiation level. While DNA was not recovered from samples at the 200 kGy exposure level, protein activity was reduced by 19 to 78%, depending on the method of cell preparation. These results demonstrate that irradiation can be effective in preventing the release of recombinant organisms intended for use in biomaterials applications without eliminating enzymatic activity and suggests that further research may indicate specific conditions whereby DNA recovery can be eliminated while retaining sufficient enzymatic activity for targeted biomaterials applications.