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U.S. Department of Health and Human Services

Vaccines, Blood & Biologics

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Improving Safety and Potency Testing of Allergen Extracts

Principal Investigator: Jay E. Slater, MD
Office / Division / Lab: OVRR / DBPAP / LI


General Overview

Allergen extracts are used in the US to diagnose and treat allergic diseases. Skin tests containing these extracts determine the causes of allergies. "Allergy shots" containing them are used to reduce or eliminate allergic symptoms. As with all drugs and biologics, good quality controls are needed to ensure that allergen extracts are safe and effective. The goal of our research is to provide new tools and data that allow allergen extract manufacturers to maintain and improve the quality of these important products.

Our work has two major areas of focus. First, we are attempting to improve the methods by which FDA and manufacturers measure the potency, or strength, of an allergen extract. Existing methods either measure a single, dominant protein in the extract, or determine the potency by measuring several undefined proteins as one group. In contrast, we are developing a method that will measure many specific proteins simultaneously. In this way, we can measure not only the overall potency but also the levels of individual proteins.

In our second project we are investigating the presence of endotoxin in certain allergen extracts. Endotoxins are ubiquitous in our environment, and are even present in some biological products; but their presence in allergen extracts has not been studied. We are using sophisticated laboratory techniques to identify the sources of endotoxins and the factors that affect endotoxin levels in these extracts.


Scientific Overview

The existing competition ELISA is a sensitive and specific method of determining overall potency, but its performance characteristics for each component allergen is uncertain. When an individual allergen is removed from the extract, the polyvalent sera cannot reliably discern its absence (Soldatova LN, et al. J Allergy Clin Immunol 2000;105:482-488; Dobrovolskaia E, et al. Clin Exp Allergy 2006; 36:525-530). Until each relevant allergen in a mixture is identified, regulators must ask manufacturers to measure overall potency. Once important allergens are determined, their measurement requires a change in technology that can be time-consuming and difficult.

The purpose of this study is to construct an assay that will have the strengths of both the RID and the competition ELISA, and that will allow manufacturers and regulators to determine the amounts of specific allergens in a mixture, as well as its overall allergenicity. Multiplex assays have been used with success for a variety of assays, such as detecting allergen-specific IgE and the amount of allergen in the environment. Following this approach, we have designed a multiplex allergen extract potency assay (MAEPA). In work so far, the assay has been optimized for cat hair and short ragweed pollen allergen extracts. We are currently developing the assay for German cockroach allergens, as well as to detect allergens in Neurospora crassa, Agarigus bisporus, and Nicotiana benthamiana/excelsiana.

We are also working to identify endotoxins in allergen extracts using bacterial genotyping by specific PCR and sequencing, and specific LPS-typing.


Publications

J Allergy Clin Immunol 2011 Aug;128(2):434
Comments on cow's milk allergy and diphtheria, tetanus, and pertussis vaccines. Exit Disclaimer
Slater JE, Rabin RL, Martin D

Ann Allergy Asthma Immunol 2010 Nov;105(5):351-8
Multiplex microbead measurements for the characterization of cat and ragweed allergen extracts. Exit Disclaimer
Devore NC, Huynh S, Dobrovolskaia EN, Slater JE

Clin Exp Allergy 2007 Jul;37(7):1033-9
Biological potency of German cockroach allergen extracts determined in an inner city population. Exit Disclaimer
Slater JE, James R, Pongracic JA, Liu AH, Sarpong S, Sampson HA, Satinover SM, Woodfolk JA, Mitchell HE, Gergen PJ, Eggleston PA

J Mol Biol 2007 May 4;368(3):742-52
Identification of a B-cell epitope of hyaluronidase, a major bee venom allergen, from its crystal structure in complex with a specific Fab. Exit Disclaimer
Padavattan S, Schirmer T, Schmidt M, Akdis C, Valenta R, Mittermann I, Soldatova L, Slater J, Mueller U, Markovic-Housley Z

Allergy Asthma Proc 2007 Mar-Apr;28(2):210-5
Characterization of the N-glycans of recombinant bee venom hyaluronidase (Api m 2) expressed in insect cells. Exit Disclaimer
Soldatova LN, Tsai C, Dobrovolskaia E, Markovic-Housley Z, Slater JE

J Endotoxin Res 2006;12(4):241-5
beta-Glucans in standardized allergen extracts. Exit Disclaimer
Finkelman MA, Lempitski SJ, Slater JE

Clin Exp Allergy 2006 Apr;36(4):525-30
Competition enzyme-linked immunosorbant assay (ELISA) can be a sensitive method for the specific detection of small quantities of allergen in a complex mixture. Exit Disclaimer
Dobrovolskaia E, Gam A, Slater JE

Arb Paul Ehrlich Inst Bundesamt Sera 2006;(95):117-27
Analyzing of ID50EAL data for the standardization of German cockroach allergen extracts in the U.S. Exit Disclaimer
James R, Mitchell H, Gergen PJ, Eggleston PA, Slater JE

J Allergy Clin Immunol 2005 Dec;116(6):1296-1300
Bacterial 16S ribosomal DNA in house dust mite cultures. Exit Disclaimer
Valerio CR, Murray P, Arlian LG, Slater JE

Dev Biol 2005;122:145-52
Characterization of allergen extracts. Exit Disclaimer
Slater JE

Clin Exp Allergy 2005 Aug;35(8):1040-8
Exploiting the avian immunoglobulin system to simplify the generation of recombinant antibodies to allergenic proteins. Exit Disclaimer
Finlay WJ, Devore NC, Dobrovolskaia EN, Gam A, Goodyear CS, Slater JE

Methods 2004 Mar;32(3):209-11
Recombinant allergens in the US. Exit Disclaimer
Slater JE

Clin Allergy Immunol 2004;18:421-32
Standardized allergen extracts in the United States. Exit Disclaimer
Slater JE

Clin Allergy Immunol 2004;18:369-86
Latex allergens. Exit Disclaimer
Slater JE

 

 

     
 

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