This part of the website is intended for U.S. healthcare professionals only.

The following abstract was presented at the American Academy of Allergy, Asthma and Immunology in San Diego in March, 2000.

SDS-Polyacrlyamide Gel Electrophoresis (PAGE) Analysis of Allergenic Extracts. GA Plunkett, LD Baldwin, RE Baker, LM Featherstone. Hollister-Stier Laboratories LLC, Spokane, WA.

Most allergenic extracts sold in the USA are non-standardized. The only standardized extracts are house dust mites and some grass extracts (potency determined by IgE binding ELISA inhibition), cat and short ragweed extracts (potency determined by the amount of a major allergen), and some insect venom extracts (potency determined by enzyme levels and total protein). Activity of non-standardized extracts relies on the Protein Nitrogen Unit (PNU) which does not correlate well with other activity assays such as IgE ELISA inhibition. The purpose of this study is to evaluate SDS-PAGE as a technique to characterize non-standardized allergenic extracts. This technique identifies proteins in extracts and separates them in a gel by their molecular weight (MW).

The method was validated by assaying one lot of a non-standardized Russian thistle extract 90 times. The study showed that the method was reproducible by 1) producing identical gel patterns and , 2) the MW of selected proteins, as determined using gel analysis software, had a variability of less than 2% (%CV). (GA Plunkett, et. al. JACI 103, S30, 1999).

Regular production batches of allergenic extracts were analyzed by SDS-PAGE. Evaluation of over 700 lots representing 170 different allergen extract types showed that most produced patterns with a unique protein array. Multiple lots of the same extract gave patterns that were similar for most allergen types, even when different lots of source material were used. For some extract types, aqueous and glycerinated extraction fluid gave different gel protein patterns. This was sometimes due to missing protein bands. In many cases, prominent proteins at MWs identified in literature references as major allergens were evident in the gels.

In conclusion, SDS-PAGE can characterize allergen extracts by producing a pattern of predominant proteins. The technique can be used to assess the source material and manufacturing conditions of extracts.