STUDIES OF ALLERGEN EXTRACT STABILITY - THE EFFECTS OF DILUTION AND MIXING

Background: However potent the allergy extracts provided by manufactur ers, they are subject to deterioration with storage, especially after dilution or mixture with other extracts. Objective: This study was per formed to assess separately the deterioration during storage in allerg en extract potency caused by dilution or by mixture with allergen extr acts that have been reported to contain proteases. Methods: To assess the effect of dilution, three serial 10-fold dilutions of cat, short r agweed, Bermuda grass, and Dermatophagoides farinae extracts were prep ared alone or combined with other extracts. They were stored at 4 degr ees for 3 and 12 months. To assess the effect of mixing with other ext racts that have been reported to contain proteases, extracts of timoth y grass, Bermuda grass, short ragweed, Russian thistle, white oak, box elder, D. farinae, and cat were stored alone or combined with one or more extracts of American cockroach, Alternaria spp., Cladosporium spp ., Penicillium spp., and a house dust mite mix for 3 months at 4 degre es C. Results: Bermuda grass, cat and house dust mite extracts incurre d significant loss of potency at all dilutions with storage. short rag weed was stable at all dilutions. Potency of extracts of timothy grass , Bermuda grass, Russian thistle, white oak, box elder, and cat were a ll reduced by combination with one or more extracts potentially contai ning proteases. Only short ragweed and D. farinae, which was in a fina l concentration of 25% glycerin, were resistant. Alternaria extract wa s most frequently responsible for loss of potency, followed by cockroa ch and Cladosporium extracts. Combination with extracts of Penicillium and a house dust mite mix did not reduce the potency of any extract. Conclusions: Both dilution alone and mixture with extracts reported to contain proteases caused loss of potency of most extracts tested. Rag weed was uniquely resistant under both conditions of storage.