Compatibility of imported fire ant whole body extract with cat, ragweed, Dermatophagoides pteronyssinus, and timothy grass allergens

Update: stability of allergen extracts to establish expiration dating

PURPOSE OF REVIEW

The article reviews studies pertaining to US manufactured allergen extract stability that contribute to guidance for expiration dating for bulk concentrates, diluted patient testing and treatment vials, and adjustments following elevated temperature excursions.

RECENT FINDINGS

Studies on allergen stability were completed to satisfy the Food and Drug Administration requirements supporting labeled expiration dating for standardized short ragweed, dust mites, cat, grass, and venom extracts and are not published. These studies demonstrated the stability enhancing parameters of 50% glycerin and support the Food and Drug Administration mandated expiration of nonstandardized extracts allowing glycerin extracts twice the dating of nonglycerin aqueous extracts. Patient vials are commonly given 6-12 months dating. There is adequate evidence that human serum albumin stabilizes low protein diluted vials. High protease allergens such as molds and insects compromised potency of pollens when mixed. Subsequent work continued to define the effects of diluents on extract dilutions, temperature excursions that occasionally occur with shipping or refrigerator malfunctions, and allergen compatibility.

SUMMARY

Potency has been determined for allergen dilutions with diluents typically used for allergen immunotherapy. These studies along with changes of potency under various storage conditions and mixing designed to improve our guidance on expiration dating of allergen extracts will be discussed.

Allergen stabilities and compatibilities in immunotherapy mixtures that contain cat, dog, dust mite, and cockroach extracts

BACKGROUND

Indoor allergen mixtures that contain cat, dog, dust mite, and cockroach extracts are commonly used in allergy clinics for subcutaneous immunotherapy, but product-specific stabilities and mixing compatibilities in these complex patient formulas have not been determined.

OBJECTIVES

To assess the recoveries of cat, dog epithelia, dog dander, dust mite Dermatophagoides farinae, and cockroach mix allergen activities in 5 component mixtures and 1:10 (vol/vol) dilutions stored for up to 12 months.

METHODS

Concentrated stock mixtures, 10-fold dilutions of these mixtures in human serum albumin-saline diluent, and analogous single-extract controls were analyzed for major allergen concentrations (cat Fel d 1, dog dander Can f 1) and multiallergen IgE-binding potencies (dog epithelia, D farinae, cockroach mix) after storage for 3, 6, 9, and 12 months at 2°C to 8°C.

RESULTS

The selected immunoassays were specific for individual target extracts in the 5-component mixtures and exhibited analytical sensitivities sufficient for evaluation of both the concentrated and diluted indoor allergen formulas. All control samples except diluted cockroach extract had near-complete stabilities during refrigerated storage. Mixtures that contained cat, dog epithelia, dog dander, and D farinae extracts exhibited favorable mixing compatibilities in 1:1 (vol/vol) concentrates (47.5% glycerin) and 1:10 (vol/vol) dilutions (4.75% glycerin), relative to corresponding control sample reactivities. Cockroach allergens in both 1:1 (vol/vol) and 1:10 (vol/vol) concentrations were stabilized significantly by mixing with the other 4 indoor allergen extracts.

CONCLUSION

Extracts in mixtures that contained 5 common sources of indoor allergens possess favorable stabilities and mixing compatibilities and support the practice of combining these products in the same patient treatment formulations for subcutaneous immunotherapy.

Mixing compatibilities of Aspergillus and American cockroach allergens with other high-protease fungal and insect extracts

BACKGROUND

Recent studies have shown that Alternaria and German cockroach allergens can be degraded by endogenous proteases from other insect and fungal extracts when combined for immunotherapy, but data supporting the compatibilities of other high-protease products in comparable mixtures have not been reported.

OBJECTIVE

To assess the stabilities and compatibilities of Aspergillus fumigatus and American cockroach allergens after mixing with protease-rich extracts from other insects or fungi at concentrations similar to those recommended for subcutaneous immunotherapy.

METHODS

Mixtures containing A fumigatus, American cockroach, and other fungal or insect extracts were evaluated by quantitative (enzyme-linked immunosorbent assays) and qualitative (immunoblotting) methods. Test mixtures and control samples at 10% to 50% glycerin concentrations were analyzed after storage for up to 12 months at 2°C to 8°C.

RESULTS

Moderate to high recoveries of Aspergillus extract activities were retained in control samples and extract mixtures under all conditions examined. American cockroach extract controls were partly degraded at 10% to 25% glycerin, and cockroach allergen compatibilities were decreased significantly in mixtures with several fungal extracts at 25% glycerin. Mixing with other insects did not compromise the stability of American cockroach allergens at 25% to 50% glycerin.

CONCLUSION

Aspergillus extracts exhibited favorable stabilities after mixing with other high-protease products. American cockroach extract potencies were unstable in less than 50% glycerin, even in the absence of other protease-containing allergens, and were destabilized in mixtures with several fungal extracts. Addition of fungal and insect extracts to separate treatment vials or preparation of fungal-insect mixtures at elevated glycerin concentrations might be necessary to produce compatible patient formulations for allergen immunotherapy injections.

Allergen stabilities and compatibilities in mixtures of high-protease fungal and insect extracts

BACKGROUND

Current practice guidelines state that protease-rich fungal and insect extracts can be combined when preparing immunotherapy vaccines, but data supporting the stability of allergens in these mixtures have not been reported.

OBJECTIVE

To determine the stabilities and compatibilities of Alternaria alternata and German cockroach allergens in mixtures with other high-protease fungal and insect (cockroach, imported fire ant) extracts at final extract concentrations consistent with injection dose targets for maintenance immunotherapy.

METHODS

Mixtures containing Alternaria, German cockroach, and other fungal and insect extracts frequently included in immunotherapy vaccines were analyzed by a combination of quantitative analyses (enzyme-linked immunosorbent assays for multiallergen immunoglobulin E [IgE]-binding potency, major Alternaria allergen Alt a 1, and major German cockroach allergens Bla g 1 and Bla g 2) and qualitative methods (immunoblotting). Mixtures and analogous single-extract controls containing 10 to 50% glycerin were evaluated after storage for up to 12 months at 2°C to 8°C.

RESULTS

Mixtures of extracts within the same phylogenetic groups (fungal-fungal, insect-insect) retained favorable Alternaria and German cockroach allergen levels and activities under most conditions examined. For several cross-taxonomic (fungal-insect) extract combinations at 10 to 25% glycerin concentrations, different immunochemical test methods measuring single (major) or multiple allergens yielded threefold to 10-fold variations in allergen recoveries.

CONCLUSION

Allergen compatibilities can be compromised in some fungal-insect extract mixtures, contrary to current immunotherapy practice parameter recommendations. Separation of these products into different treatment vials may be required to produce stable mixtures for subcutaneous immunotherapy. Data from assay methodologies with distinct binding specificities provide a critical assessment of allergen activities in high-protease extract mixtures.

Allergen compatibilities in extract mixtures

Stability studies with a few well-characterized allergen extracts have yielded useful information about the shelf-life of these products stored under various conditions. The development of validated stability-indicating tests and their clinical verification remains a fundamental challenge for extending this information to cover more products. This challenge becomes even greater for evaluations of more complex, multiextract mixtures that are used in clinical practice. Thus, the current approach for developing guidelines for extract expiration dating practices must rely on extrapolations of data obtained from a few well-controlled studies.

Stability and mixing compatibility of dog epithelia and dog dander allergens

BACKGROUND

Little information or data are available concerning the stability and compatibility of dog epithelia and dog dander allergens.

OBJECTIVE

To determine the immunochemical reactivities of commercial, nonstandardized dog epithelia and dog dander extracts after exposures to various temperatures or after mixing with high-protease fungal and cockroach extracts at concentrations recommended for maintenance immunotherapy (IT) injections.

METHODS

Quantitative enzyme-linked immunosorbent assay and qualitative (immunoblot) analyses were performed to compare specific compositional changes with total or individual allergen activities. Assays for dog allergens Can f 1 and Can f 3 (albumin) used specific mouse or rabbit antibodies. Multiallergen enzyme-linked immunosorbent assay inhibition and immunoblot methods were conducted using a human serum pool with high levels of IgE to dog allergens.

RESULTS

Dog allergen recoveries ranged from 22% to 134% after short exposures to moderate or extreme temperatures and from 28% to 118% after mixing with fungal or insect extracts and storage for up to 15 months at 2 degrees C to 8 degrees C. Recoveries in dog dander extracts varied up to 2.5-fold with different test methods. Immunoblots revealed partial degradation of dog albumin molecules to discrete fragments that retained antibody-binding activities. In most cases, recoveries improved at elevated glycerin concentrations.

CONCLUSIONS

Dog allergens in epithelia and dander extracts exhibited favorable temperature stabilities. Compatibilities with fungal or insect extracts may be compromised or at risk in some combinations. These data support current IT practice parameter recommendations of separating high-protease extracts from other products if possible; they also demonstrate that dog extracts possess allergen stabilities suitable for many IT formulations.