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Open Access Highly Accessed Research

Immunohistochemical detection of mutations in the epidermal growth factor receptor gene in lung adenocarcinomas using mutation-specific antibodies

Yan Xiong1, Yun Bai1, Nufatt Leong2, Todd S Laughlin2, Paul G Rothberg2, Haodong Xu2, Lin Nong1, Jing Zhao1, Ying Dong1 and Ting Li1*

Author Affiliations

1 Department of Pathology, Peking University First Hospital, 7 Xishiku Street, Xicheng District, Beijing, 100034, China

2 Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY, 14642, USA

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Diagnostic Pathology 2013, 8:27  doi:10.1186/1746-1596-8-27

Published: 18 February 2013

Abstract

Background

The recent development of antibodies specific for the major hotspot mutations in the epidermal growth factor receptor (EGFR), L858R and E746_A750del, may provide an opportunity to use immunohistochemistry (IHC) as a screening test for EGFR gene mutations. This study was designed to optimize the IHC protocol and the criteria for interpretation of the results using DNA sequencing as the gold-standard.

Methods

Tumor sections from fifty lung adenocarcinoma specimens from Chinese patients were immunostained using L858R and E746_A750del-specific antibodies using three different antigen retrieval solutions, and the results were evaluated using three different sets of criteria. The same specimens were used for DNA purification and analysis of EGFR gene mutations.

Results

In this study the optimal buffer for antigen retrieval was EDTA (pH 8.0), and the optimal scoring method was to call positive results when there was moderate to strong staining of membrane and/or cytoplasm in >10% of the tumor cells. Using the optimized protocol, L858R-specific IHC showed a sensitivity of 81% and a specificity of 97%, and E746_A750del-specific IHC showed a sensitivity of 59% and a specificity of 100%, both compared with direct DNA analysis. Additionally, the mutant proteins as assessed by IHC showed a more homogeneous than heterogeneous pattern of expression.

Conclusions

Our data demonstrate that mutation-specific IHC, using optimized procedures, is a reliable prescreening test for detecting EGFR mutations in lung adenocarcinoma.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2059012601872392 webcite

Keywords:
Lung adenocarcinoma; Epidermal growth factor receptor; Mutation; Immunohistochemistry