Elsevier

Autoimmunity Reviews

Volume 11, Issue 9, July 2012, Pages 642-645
Autoimmunity Reviews

Review
Importance of the dense fine speckled pattern on HEp-2 cells and anti-DFS70 antibodies for the diagnosis of systemic autoimmune diseases

https://doi.org/10.1016/j.autrev.2011.11.005Get rights and content

Abstract

The presence of anti-nuclear antibodies (ANA) is a hallmark of systemic autoimmune rheumatic diseases (SARD). The indirect immunofluorescence (IIF) assay on HEp-2 cells is a commonly used test for the detection of ANA and was recently recommended as the screening test of choice by a task force of the American College of Rheumatology. However, up to 20% of serum samples from healthy individuals (HI) have been reported to have a positive ANA test, the majority of which are directed to the dense fine speckles 70 (DFS70) antigen. Even more important, the DFS IIF pattern has been reported in 33% of ANA positive HI, but not in ANA positive SARD sera. Since the intended use of the ANA HEp-2 test is to aid in the diagnosis of SARD, the reporting of anti-DFS70 antibodies and their associated pattern (DFS) as a positive test, significantly reduces the specificity and the positive likelihood of the ANA test. This has significant implications for diagnostic algorithms involving the detection of ANA. We summarize the current knowledge of anti-DFS70 antibodies and their impact on ANA testing. We also suggest a test algorithm which considers the DFS pattern and the presence of anti-DFS70 antibodies. In addition, we describe a novel method based on immunoadsorption of anti-DFS70 antibodies, which increases the specificity of the ANA HEp-2 test for SARD and which has the potential to overcome a significant limitation of the ANA HEp-2 assay.

Section snippets

History and clinical association of anti-DFS70 antibodies

The presence of autoantibodies directed against intracellular antigens, including anti-nuclear antibodies (ANA), is a hallmark of systemic autoimmune rheumatic diseases (SARD) [1]. Despite significant advances in diagnostic technologies [2], [3], the indirect immunofluorescence (IIF) assay using HEp-2 cells continues to be one of the most commonly used routine tests for the detection of ANA. This is reflected in the recommendations of a task force commissioned by the American College of

Indirect immunofluorescence picture of anti-DFS70 antibodies and cellular function of LEDGF

The typical IIF staining pattern has been described as dense fine speckles that are somewhat uniformly distributed throughout the nucleus accompanied by metaphase chromatin staining [19] (Fig. 1). Since a 70-kDa protein was recognized by immunoblotting, the antigen was initially termed DFS70, but the primary target autoantigen was later identified as the lens epithelium-derived growth factor (LEDGF) [20], now known to be DNA binding transcription coactivator p75 (reviewed in Ref. [9]). This

Advances in ANA testing by indirect immunofluorescence

Several improvements have been made to the ANA HEp-2 assay including the use of cell lines that over-express target antigens after transfection of a cognate cDNA [22], antigen supplements in the form of micro dots, and optimized mitotic cell lines. At the technical platform level, digital imaging systems for automated reading, archiving and interpretation of the results have been reported to provide good positive/negative discrimination [23], [24]. In addition, promising results have been

Consequences for ANA testing — a new algorithm

With advances in autoimmunity research and the availability of new autoantibody assays, it is important to develop and implement novel test algorithms for the diagnosis of SARD. A close collaboration between clinicians and laboratory specialists is required to increase the efficiency, performance and validity of any testing cascade. Recently, using a multi-center approach, a novel consensus test algorithm has been established and implemented in a broad geographic area in Italy [25]. However,

Immunoadsorption of anti-DFS70 antibodies

In a recent study, the DFS IIF pattern was found in 33.1% of ANA positive healthy individuals compared to 0.0% of ANA positive patients with SARD (p < 0.0001), which significantly affects the diagnostic power and efficiency of the IIF assay. Therefore, accurate pattern recognition and appropriate interpretation and reporting of results are important because it could influence the referral of patients with a positive ANA for unnecessary tertiary care consultation. Since the identification of the

Abbreviations

    ANA

    anti-nuclear antibody

    DFS

    dense fine speckled

    HI

    healthy individuals

    IIF

    indirect immunofluorescence

    SARD

    systemic autoimmune rheumatic disease

    SLE

    systemic lupus erythematosus

Disclosure statement

M. Mahler is employed at INOVA Diagnostics Inc. selling antibody assays to aid in the diagnosis of autoimmune diseases. M.J. Fritzler is a consultant to ImmunoConcepts, BioRad and INOVA Diagnostics. J.G. Hanly has no conflict of interest.

Take-home messages

  • The dense fine speckled (DFS) pattern is rarely found in isolation in systemic autoimmune rheumatic disease sera, but frequently in sera from apparently healthy individuals. Therefore, it is important to recognize this pattern and confirm the reactivity to DFS70 by a specific assay.

  • The DFS pattern on ANA IIF and the testing for anti-DFS70 antibodies need to be considered in diagnostic algorithms of ANA testing in the context of SARD — a new algorithm has been proposed.

  • Adsorption of anti-DFS70

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