ENA Screen ELISA Kit (Extractable Nuclear Antigens)

Full Name: ENA Screen ELISA Kit (Extractable Nuclear Antigens)
Reactivity: Human
Sample Type: Plasma, Serum
Sensitivity: Diagn. 92.7%

BACKGROUND

Extractable nuclear antigens (ENA) are linked to connective tissue disorders (CTD) and can be mainly classified as either being either nuclear or soluble cytoplasmic antigens. Generally there greater than 100 different types that have been identified, however, there are 6 main groups which are frequently used in research laboratories in order to investigate Sjögren’s syndrome, systemic lupus erythematosus (SLE) and mixed connective disease (MCTD). These are anti-La and anti-Ro for Sjögren’s, anti-Scl70 and anti-Jo for Dermatomyositis, anti-Sm for SLE and anti-RNP for MCTD.

Two gel based methods immuno-electrophoresis and double immunodiffusion have been frequently used to discover anti-ENAs and how they are linked to their respective diseases, both procedures require antigen precipitation for a valid result being obtained. Other procedures that have been used include western blotting, enzyme linked immunosorbent assay (ELISA) and passive hemagglutination.

At present, the ELISA method is the most popular technique for detecting anti-ENAs, this is due to the fact it is quantitative, easy to perform and can be scaled up to generate high volume output. The sensitivity and specificity generated for these procedures will depend on the assay or test that is being carried out and this will vary between each laboratory.

INTENDED USE

Human ENA screen ELISA kit can be used to screen in-vitro quantitative concentrations IgG auto-antibodies directed against extractable nuclear antigens (ENAs, ENA screen) in human serum and plasma samples. This assay has a minimum analytical sensitivity limit of diagn. 92.7%.

A mixture of purified antigens SS-A 60, SS-A 52, SS-B, Sm, RNP/Sm, Scl 70 and Jo-1 is coated on to microwells.

CONTENT

All reagents supplied need to be stored at 2 °C – 8 °C, unopened reagents will retain reactivity until expiration date. Do not use reagents beyond this date.

• Divisible Microplate: Consisting of 12 modules of 8 wells, highly purified human extractable nuclear antigens bound to microwells.
• Control A (Negative), Control B (Cut-Off), Control C (Positive): Containing ENA antibodies in a serum/buffer matrix.
• Sample Buffer (5x).
• Enzyme Conjugate: Contains anti-human IgG antibodies, HRP labelled.
• TMB Substrate.
• Stop Solution: Contains acid.
• Wash Buffer (50x).
• Instruction for Use.
• Certificate of Analysis.

SENSITIVITY

The minimum detection sensitivity level of IgG antibodies directed to human extractable nuclear antigens screen (ENAs) using current ENA screen ELISA kit was diagn. 92.7%. The dynamic range for this assay is to a cut-off index 1.0.

ASSAY CHARACTERISTICS

– Expected Values: Cut-Off 1.0
– Results Interpretation: Negative Index: < 1.0, Positive Index ≥ 1.0
– Intra Assay Precision: 1.6 – 6.0%
– Inter Assay Precision: 1.2 – 6.9%
– Interfering Substances: None
– Clinical Diagnosis: Sensitivity (92.7%), Specificity (96.3%), Overall agreement (94.8%).

REFERENCES

1. Efficiency of different strategies to detect autoantibodies to extractable nuclear antigens. J Immunol Methods. (2010) 360 (1-2): 89-95. Almeida González D., et al.
2. Comparison of two extractable nuclear antigen testing algorithms: ALBIA versus ELISA/line immunoassay. Pathology. (2016) 48 (5): 491-7. Chandratilleke D., et al.
3. How should a district general hospital immunology service screen for anti-nuclear antibodies? An ‘in-the-field’ audit. Clin Exp Immunol. (2015) 180 (1): 52-7. Hira-Kazal R., et al.
4. Application of linear discriminant analysis in performance evaluation of extractable nuclear antigen immunoassay systems in the screening and diagnosis of systemic autoimmune rheumatic diseases. Am J Clin Pathol. (2012) 138 (4): 596-603. Pi D., et al.

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• ENA Combi ELISA Kit
• ENA-4 Profile ELISA Kit
• ENA-6 Profile ELISA Kit