Session Information
Session Title: Systemic Lupus Erythematosus - Clinical Aspects and Treatment: Biomarker, Translational and Nephritis Studies
Session Type: Abstract Submissions (ACR)
Background/Purpose
Anti-dsDNA antibodies (aab) are known as important serological marker to aid in the diagnosis of systemic lupus erythematosus (SLE) and are part of the ACR classification criteria. In addition, anti-ribosomal P (Rib-P) AAB are a specific diagnostic marker for SLE. Lately, anti-Ku AAB were also described to be present with a high prevalence in SLE patients. Here we describe the evaluation of new chemiluminescent immunoassays (CIA, QUANTA Flash®) for the detection of anti-Rib-P and anti-Ku AAB, and show that testing for these AAB might add value to the diagnosis of SLE.
Methods
Sera (125) from patients suffering from SLE and 280 control sera including rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA), psoriatic arthritis (PsA) ancylosing spondylitis (AS) and healthy controls (HC) were tested using QUANTA Flash Ribosomal P, QUANTA Flash dsDNA, and QUANTA Flash Ku (prototype).
Results
58/125 of the SLE Patients and 13/280 controls tested positive for antibodies against dsDNA corresponding to a sensitivity of 46.6% ( 95% CI of 37.4-55.5%) and a specificity of 95.4% ( 95% CI of 92.2-97.5%). 37/125 of the SLE patients and 14/280 controls tested positive for anti-Rib-P AAB corresponding to a sensitivity of 29.6% (95% CI: 21.8-38.4%) and a specificity of 95.0% (95% CI: 91.8-97.2%). In addition, 20/125 of the SLE patients and 5/280 controls sera tested positive for anti-Ku AAB corresponding to a sensitivity of 16.0% (95% CI: 10.1-23.6%) and a specificity of 98.2% (95% CI: 95.9-99.4 %). The reactivities against Rib-P and Ku show minimal overlap. Therefore, when combining the two markers, the sensitivity and specificity for SLE were 41.6% (95% CI: 32.9-50.8%) and 93.2% (95% CI: 89.6-95.9%), respectively. Table 1 part A shows a summary.
In the group of dsDNA negative samples anti-Ku (OR=8.1) and anti-Rib-P(OR=2.3) results could be used to discriminate SLE patients from controls. 16 /67 sera from SLE patients and 18/267 control sera had a positive test result for either anti-Rib-P or anti-Ku, thus discriminating SLE from controls with a specificity of 93.3% (95% CI 89.6-96.0%). Table 1 part B shows the individual and combined sensitivities, specificities and Odd ratios.
Table 1 Sensitivities, specificities and Odd ratios summarized (Part A: complete cohort, Part B: dsDNA negative sub cohort)
|
QUANTA Flash® |
Sensitivity |
95% CI |
Specificity |
95% CI |
OR |
95% CI |
|
Part A: complete cohort (n=405) |
|
|
|
|
|
|
|
dsDNA |
46.6% |
37.4-55.5% |
95.4% |
92.2-97.5% |
17.8 |
9.2-34.3 |
|
Rib-P |
29.6% |
21.8-38.4% |
95.0% |
91.8-97.2% |
8.0 |
4.1-15.5 |
|
KU |
16.0% |
10.1-23.6% |
98.2% |
95.9-99.4 % |
10.5 |
3.8-28.6 |
|
either Rib-P or Ku |
41.6% |
32.9-50.8% |
93.2% |
89.6-95.9% |
9.8 |
5.4-17.6 |
|
Part B: dsDNA negative sub cohort (n=334) |
|
|
|
|
|
|
|
Ku |
13.4% |
6.3-24.0% |
98.1% |
95.7-99.4% |
8.1 |
2.6-25.2 |
|
Rib-P |
10.4% |
4.3-20.3% |
95.1% |
91.8-97.4% |
2.3 |
0.9-6.0 |
|
either Rib-P or Ku |
23.9% |
14.3-35.9% |
93.3% |
89.6-96.0% |
4.3 |
2.1-9.1 |
Conclusion
Our data confirm that anti-Rib-P and anti-Ku AAB represent potentially useful biomarkers to aid in the diagnosis of SLE. Interestingly, the reactivity against these two antigens shows only minimal overlap and thus, the combination of both markers showed high sensitivity and specificity for SLE. In addition, a significant portion of anti-dsDNA negative SLE patients were positive for anti-Rib-P or anti-Ku AAB. More studies will be needed to confirm this observation.
Disclosure:
J. Schulte-Pelkum,
Inova Diagnostics, Inc.,
3;
D. Carmona-Fernandes,
None;
M. J. Santos,
None;
R. Albesa,
Inova Diagnostics, Inc.,
3;
M. Mahler,
Inova Diagnostics, Inc.,
3.
« Back to 2014 ACR/ARHP Annual Meeting
ACR Meeting Abstracts - https://acrabstracts.org/abstract/added-value-of-the-determination-of-anti-ribosomal-and-anti-ku-antibodies-for-diagnosis-of-systemic-lupus-erythematosus/