Stability of Major Allergen Proteins in Extract Mixes Diluted in Human Serum Albumin (HSA), Normal Saline (NSP), or Glycerin (GLY)

Abstract

RATIONALE: The stability of allergen proteins in extract mixes serially diluted in NSP, HSA, or GLY and stored refrigerated for 1 year or 1 month at room temperature was investigated. Major allergen levels in grass (Gr 5), mite (Group 1 and 2), cat (Fel d 1), birch (Bet v 1), olive (Ole e 1), English plantain (Pla l 1), mugwort/sage (Art v 1), and Bermuda (Cyn d 1) were measured.METHODS: Five mixes of extracts from ALK-Abelló were made and diluted 5 fold. Cockroach, Aspergillus, or mixed mold extract was added to a portion of the 1:5v/v dilution. Some vials were stored at room temperature. Major allergens were measured using very sensitive direct binding ELISA methods.RESULTS: Most allergens had at least 50% of their activity after 3 months in all diluents. At 6 months olive, English plantain, Bermuda, birch and mite allergens began to lose activity in dilution 1:125v/v in NSP but lost almost all major allergen in dilution 1:625v/v in NSP or GLY. All allergens except Bermuda were stable at 6 months in HSA and all except Bermuda, English plantain and birch were stable at 12 months. Cockroach extract degraded all the allergens except for mite proteins. Molds degraded the grass, olive and plantain allergens significantly. Allergens maintained >40% of their activity after 1 month at room temperature.CONCLUSIONS: Allergen proteins have different stability profiles depending on the protein, the diluent, and the concentration. Some proteins in dilute solutions without added albumin protein lost ELISA binding activity in glycerinated and aqueous diluents. RATIONALE: The stability of allergen proteins in extract mixes serially diluted in NSP, HSA, or GLY and stored refrigerated for 1 year or 1 month at room temperature was investigated. Major allergen levels in grass (Gr 5), mite (Group 1 and 2), cat (Fel d 1), birch (Bet v 1), olive (Ole e 1), English plantain (Pla l 1), mugwort/sage (Art v 1), and Bermuda (Cyn d 1) were measured. METHODS: Five mixes of extracts from ALK-Abelló were made and diluted 5 fold. Cockroach, Aspergillus, or mixed mold extract was added to a portion of the 1:5v/v dilution. Some vials were stored at room temperature. Major allergens were measured using very sensitive direct binding ELISA methods. RESULTS: Most allergens had at least 50% of their activity after 3 months in all diluents. At 6 months olive, English plantain, Bermuda, birch and mite allergens began to lose activity in dilution 1:125v/v in NSP but lost almost all major allergen in dilution 1:625v/v in NSP or GLY. All allergens except Bermuda were stable at 6 months in HSA and all except Bermuda, English plantain and birch were stable at 12 months. Cockroach extract degraded all the allergens except for mite proteins. Molds degraded the grass, olive and plantain allergens significantly. Allergens maintained >40% of their activity after 1 month at room temperature. CONCLUSIONS: Allergen proteins have different stability profiles depending on the protein, the diluent, and the concentration. Some proteins in dilute solutions without added albumin protein lost ELISA binding activity in glycerinated and aqueous diluents.