Influence of the definition of the standardization unit on the in vitro potency of cat allergen extracts

Abstract

In a previous study, we conducted an in vitro comparison of two sublingual allergy immunotherapy products, namely, house dust mite (HDM) Staloral 300 IR/mL produced by Stallergenes Greer, and HDM Osiris 300 IR/mL produced by ALK-Abelló. Although both products are labeled with the same unit, that is, the index of reactivity (IR), the definition of this unit is different depending on the product. This resulted in HDM Staloral 300 IR/mL displaying a higher total allergenic activity (TAA) and higher contents in major allergens and proteins. The aim of this study was to extend the comparison to cat sublingual extracts, that is, to cat Staloral 300 IR/mL from Stallergenes Greer and cat Osiris 300 IR/mL from ALK-Abelló. While both cat allergen extracts were qualitatively similar, in that they exhibited similar protein and allergen profiles, cat Staloral 300 IR/mL displayed a 2 times higher TAA than cat Osiris 300 IR/mL (according to an in-house method) and contained 1.6 time more proteins, 1.3 and 1.9 time more major allergens Fel d 1 and Fel d 4, respectively. No conclusions on clinical efficacy or safety can be drawn from these data.

Keywords

Allergen extract / allergenic activity / allergen immunotherapy / cat / characterization / major allergen / standardization / unit definition

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