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ANA HEp2 & Abs anti DFS 70

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Introducing ANA HEp2 DFS70 KO, a new tool to interpret ANA HEp-2 and distinguish DFS70 positive samples

Testing for ANA by IFA can yield positive results caused by many different autoantibodies, including anti-DFS70, which has no known association with systemic autoimmune or rheumatic disease.

Anti-DFS70 antibodies are responsible for a certain percentage of positive HEp-2 results in routine testing, and may contribute to unnecessary anxiety on patients and doctor as well as added cost to the healthcare system. The DFS pattern (Dense Fine Speckled) may be confused with other patterns associated primarily with systemic lupus erythematosus, Sjögren's syndrome and mixed connective tissue disease"

The detection of anti-DFS70 antibodies can eliminate unnecessary reflex testing, to exclude that the ANA HEp2 positive result is not related to CTD, or RA.

Background: Clinical and Diagnostic laboratories often encounter sera that produce a dense fine speckled pattern that stains the nucleoplasm of interphase cells and chromatin of cells undergoing mitosis.

Significance: Most of the literature indicates that this pattern is widely prevalent and associated with an antigen called LEDGF/PSIP1/DFS70.

When should a DFS70 confirmatory test be used?

Since a positive ANA test is an important component in the triage and diagnosis of patients with possible SARD, ANA HEp-2 testing outside an appropriate clinical setting may yield a sizable portion of ANA positive apparently healthy individuals, a false positive indeed.The implications of an incorrect recognition of DFS70 antibodies also include the costs (financial and otherwise) of downstream testing and patient care to follow up on any false-positive ANA results.

Therefore, samples with an apparent DFS staining pattern identified by IFA, should be tested for anti-DFS70 antibodies by a specific confirmatory assay.

Clinicians should not overestimate positive ANA results in patients with isolated anti-DFS70 antibodies and focus on the patients' clinical symptoms

The Zenit Immco ANA HEp2 DFS70 KO solution

With the new substrate Zenit Immco ANA HEp2 DFS70 KO, the user can detect the presence of anti-DFS70 antibodies, and use in addition to standard HEp-2 ANA patterns with no impact on daily routine.

This new, enhanced substrate allows:

  1. To detect ANA and DFS70 Abs at a glance
  2. To detect ANA and DFS70 Abs in a single step
  3. No additional DFS70 Ab confirmatory test
  4. Time saving; screening and DFS70 detection in the same step
  5. Cost saving; screening and DFS70 detection in the same step

IMMCO DFS70 Knock Out HEp-2 cells

Approx. 90% of HEp-2 on each well of the substrate are cells KO (Knocked Out) for psip1 gene which produces the antigen LEDGF responsible for DFS70 pattern. The other 10% of the cells are conventional HEp-2 cells which express high level of the antigen.

- This HEp-2 presentation aids in easier identification and distinction of DFS70 pattern from other similar patterns (fine speckled or homogeneous).

- Aids in unmasking the DFS70 (due to LEDGF-psip1) pattern and revealing any underlying ANA reaction that may be associated with SARD if a mixed pattern is present

Does not compromise the ability of the HEp-2 substrate in detecting other ANAs

HEp2 Substrate with conventional and knocked out cells for DFS70/PSIP1 gene

Engineered HEp2: psip1 gene has been knocked out of Hep2 cells and mixed with wild type cells to produce a new generation of substrate.
This new substrate preserves the traditional autoantibody reactivity. When reacted with a sera positive for DFS70 specific serum, KO cells are less intense compared to wild type which aids in the analysis of the sample. This improved substrate also has the potential to unmask the underlying ANA patterns that were previously masked by a high titer DFS70 reaction.

 

Example images of 20x field for labeled Engineered HEp2 substrate using a positive sera for DFS70 antibodies

Homogeneous on DFS70 substrate

Speckled on DFS70 substrate

The new product range:

  • 48135 ANA HEP-2 DFS70 KO SUBSTRATE (12 WELLS) IMMCO #2298
  • 48136 ANA HEP-2 DFS70 KO SUBSTRATE KIT (60 TESTS) IMMCO #1108
  • 48137 ANA HEP-2 DFS70 KO SUBSTRATE KIT (120 TESTS) IMMCO #1108-120
  • 48193 ANA HEp2 DFS70 KO SUBSTRATE KIT (240 TESTS) IMMCO #1108-240
  • 48138 DFS70 POSITIVE CONTROL IMMCO #2284