A new and safer method for preserving allergen stability in human vaccines

Abstract

Rationale Specific allergen immunotherapy is the only treatment that reverses the immunologic imbalance responsible for causing IgE-medicated symptoms. Each allergen vaccine, however, is a mixture of glycoproteins that have varying stabilities in solutions. Currently, human serum albumin (HSA) is widely used as a stabilizing agent in FDA licensed vaccines, which creates a potential risk for the transmission of prion-induced illnesses. We have, therefore, developed a new and safer method of preserving allergen vaccines to eliminate the need for HSA in allergen vaccines. Methods Over a period of 40 weeks, we studied the stability of commercially available vaccines using three methods of preservation: HSA, phosphate buffered saline (PBS), and trehalose. Allergen vaccines were diluted and stored similar to our allergy clinic's routine, and samples studied for specific allergen concentrations using monoclonal reagents. Freezing and thawing effects were also analyzed. The major allergens included in this study were cat (Fel d1), cockroach (Bla g1), and Der f1 from D. farinae. Results Trehalose was comparable to HSA in preserving the antigenicity of both cat and cockroach allergens. Trehalose was superior to both HSA and PBS in stabilizing the mite allergen Der f1. Conclusions These initial studies support the use of trehalose in the stabilization of allergen vaccines intended for human use. The potential transmission of prion proteins to patients who are given allergy injections that contain human serum albumin can thus be totally avoided. Future studies will determine if this patent pending trehalose method proves to be as effective in other commonly used allergen vaccines.