Quality control of non-standardized allergenic extracts: Major allergen and IgE binding of birch, English plantain and olive pollen

Abstract

Rationale The objective of these studies is to apply quality control techniques used to determine the potency of standardized allergenic extracts to assess the quality of non-standardized weight/volume, PNU, and alum adsorbed extracts. An outcome of this objective is the determination of appropriate methods to manufacture consistent well-characterized extracts. Methods Non-standardized birch, English plantain, and olive pollen extracts were tested. Multiple consecutive lots manufactured over 2-3 years were measured for major allergens Bet v 1, Pla l 1, and Ole e 1 using direct binding ELISAs obtained from ALK-Abelló, Madrid and validated in our laboratory. IgE binding ELISAs were performed using sera pools from at least 5 patients allergic to the allergen. Electrophoresis and immunoblotting were also performed. Results Most extracts had good consistency by either IgE binding or major allergen, although some lots show a significant deviation from the average. English plantain and birch had a few lots that were much lower in major allergen than the average. Aqueous extracted olive pollen extracts showed consistency as did glycerin extracted pollen, however a significant reduction in extractability of the major allergen with glycerin was observed. Some olive pollen raw material source lots showed significant differences in Ole e 1. IgE binding ability was well correlated with Bet v 1 in birch extracts. Major allergens were also measured in alum adsorbed extracts. Conclusions These studies demonstrate the benefit for testing potency in non-standardized extracts and will provide the means to produce consistent products in the interim before FDA standardized products become available.