ACPA ELISA Kit (Anti-Citrullinated Protein Antibodies)
INTENDED USE
Human ACPA ELISA kit is a method intended for analysing in vitro quantitative levels of IgG antibodies against citrullinated protein (anti-citrullinated protein antibodies, ACPA) in human plasma and serum. This assay kit has a minimum analytical sensitivity limit of 1.0 U/ml.
BACKGROUND
Anti-citrullinated protein antibodies (ACPA) are autoantibodies that are usually present in majority of patients which have rheumatoid arthritis (RA) and are directed against proteins and peptides that are citrullinated. The first members of this autoantibody family were discovered in the 1970s, these were anti-perinuclear factor and anti-keratin antibodies. However, later studies have demonstrated that autoantibodies from RA patients are able to react with many different citrullinated antigens such as vimentin, fibrinogen and deiminated epstein-barr virus nuclear antigen 1.
There is a citrullinated protein which have been identified to be in rheumatoid synovial tissue of RA patients. Also, the titre of antibodies against vimentin in RA patients shows a direct correlation with the disease activity score. The predominate diagnosis that is used for RA during serological and clinical protocols has been limited to the measurement of autoantibodies against rheumatoid factor (RF). This only has a moderate specificity of about 70% for RA, however, several recent studies have discovered that antibodies against citrullinated arginine residues that AR found in filament proteins are also displayed in patients that are negative for RF.
Rheumatoid arthritis (RA) has been found to display distinct profiles for autoantibodies, this is highlighted by the serum samples from positive patients of anti-CCP to react with many different citrullinated target proteins. There are studies that have identified ACPA reactivity present in anti-CCP negative patients. The predominate goal using these autoantibodies is to be able to carry out early interventions to patients that may be at risk to developing RA at a later age. Also, the use of peptide library screening procedures has allowed other antigens to be selected and for 2nd or 3rd generation CCP assays to be developed.
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: Bound by anti-citrullinated protein antibodies.
- Calibrator A-F: Concentrations 0, 20, 40, 100, 300, 1000 U/ml.
- Control Positive and Control Negative.
- Sample Buffer (5x).
- Enzyme Conjugate: Anti-human IgG antibodies, HRP labelled.
- TMB Substrate.
- Stop Solution.
- Wash Buffer (50x).
- Instruction for Use.
- Certificate of Analysis.
SENSITIVITY
The minimum detection sensitivity level of human anti-citrullinated protein antibodies using current ACPA ELISA kit was 1.0 U/ml. The dynamic range for this assay is 20.0 – 1,000.0 U/ml.
ASSAY CHARACTERISTICS
– Measuring Range: 0 – 1000 U/ml
– Expected Values: In a normal range = Cut-off 20 U/ml, Negative = < 20 U/ml, Positive = ≥ 20 U/ml.
– Linearity: 85 – 109%
– Intra Assay Precision: 4.6 – 6.4%
– Inter Assay Precision: 5.3 – 9.2%
– Clinical Diagnosis: Sensitivity (81.2%), Specificity (98.0%), Overall agreement (91.4%).
REFERENCES
- Genetics of ACPA positive rheumatoid arthritis: the beginning of the end? Ann Rheum Dis. (2011) 70 Suppl 1: i51-4. Review. de Vries R.R., et al.
- The lung in ACPA-positive rheumatoid arthritis: an initiating site of injury? Rheumatology (Oxford). (2014) 53 (11): 1940-50. Review. Perry E., et al.
- The role of anti-citrullinated protein antibodies in the early stages of rheumatoid arthritis. Curr Opin Rheumatol. (2016) 28 (3): 275-81. Review. Dekkers J., et al.
- Anti-citrullinated peptide antibody: death of the rheumatoid factor? Med J Aust. (2009) 190 (12): 693-5. Review. Chatfield S.M., et al.
ADDITIONAL INFORMATION
- Full Name: ACPA ELISA Kit (Anti-Citrullinated Protein Antibodies)
- Reactivity: Human
- Sample Type: Serum, Plasma
- Sensitivity: 1.0 U/ml
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