Measurement of German cockroach allergens and their isoforms in allergen extracts with mass spectrometry

Samuel T Mindaye; Natalie A David; Sayyed Amin Zarkesh Esfahani; Coby Schal; Elizabeth C Matsui; Ronald L Rabin; Jay E Slater

doi:10.1111/cea.13604

Measurement of German cockroach allergens and their isoforms in allergen extracts with mass spectrometry

Clin Exp Allergy. 2020 Jun;50(6):741-751. doi: 10.1111/cea.13604. Epub 2020 May 20.

Authors

Samuel T Mindaye¹, Natalie A David¹, Sayyed Amin Zarkesh Esfahani¹, Coby Schal², Elizabeth C Matsui³, Ronald L Rabin¹, Jay E Slater¹

Affiliations

¹ Laboratory of Immunobiochemistry, Division of Bacterial, Parasitic, and Allergenic Products, Office of Vaccines Research and Review, CBER/FDA, Silver Spring, MD, USA.
² Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA.
³ Department of Population Health and Pediatrics, Dell Medical School, The University of Texas at Austin, Austin, TX, USA.

PMID: 32243003
DOI: 10.1111/cea.13604

Abstract

Background: Allergen extracts are the primary tool for diagnosis and treatment of allergic diseases. In the United States, most allergen extracts are non-standardized. More sophisticated analytical approaches are needed to characterize these products and enable manufacturers and regulators to better determine potency.

Objective: To expand the multiple reaction monitoring (MRM) assay for an in-depth characterization of German cockroach (GCr; Blattella germanica) allergen extracts.

Methods: We applied advanced liquid chromatography (LC) and mass spectrometry (MS) techniques including MRM. The expanded LC/MRM-MS method was optimized to measure known GCr allergens and their isoforms/variants in commercial extracts and environmental samples. We performed isoform-specific allergen measurements in multiple extracts from four commercial sources and extracts prepared using environmental samples from urban homes. To investigate causes of heterogeneity, we examined over 30 extraction process variables.

Results: Evaluation of the commercial extracts confirmed the variability of production lots and commercial sources. Commonly used defatting and extraction protocols yielded extracts with comparable allergen profiles and content. However, the identity and quality of source materials was a major contributor to variability. In comparing commercial GCr extracts to environmental samples, relative quantities of Bla g 1, Bla g 2, Bla g 3, Bla g 4 and Bla g 11 were similar, while Bla g 5, Bla g 6, Bla g 7 and Bla g 8 were present in the environmental samples but largely absent for the commercial extracts.

Conclusions and clinical relevance: LC/MRM-MS can be used to measure all known GCr allergens in commercial allergen extracts and environmental samples. Significant differences exist between allergen profiles of commercial extracts and the profiles of environmental samples from dwellings. This analytical platform can serve as a template to achieve better product characterization of similarly complex products.

Keywords: allergens and epitopes; regulatory aspects; venom and insect allergy.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.
Research Support, U.S. Gov't, P.H.S.

MeSH terms

Allergens / chemistry*
Animals
Blattellidae / chemistry*
Chromatography, Liquid
Complex Mixtures / chemistry*
Insect Proteins / chemistry*
Mass Spectrometry

Substances

Allergens
Complex Mixtures
Insect Proteins