Session Information
Session Type: Abstract Submissions (ACR)
Background/Purpose:
Detection of auto-antibody is informative for diagnosis of SSc. Line blot assay (LBA) provides a quantitative in vitro assay for detecting human IgG class auto-antibodies against 13 different antigens simultaneously. The aim of our study is to evaluate availability of LBA for SSc in clinical setting, and assessing the sensitivity comparing with other conventional assay.
Methods:
LBA strips coated with thin parallel lines of 13 synthesized antigen (CENPA, CENPB, U1RNP, fibrillarin, RNAPIII(RP11�ARP155), NOR90, Th/To, PM-Scl100, PM-Scl75, Ku, Ro-52, PDGFR ) captures serum auto antibody. Captured autoantibody is detected by Alkaline Phosphatase conjugated second antibody combined with automated scan system. Serum samples from SSc patients in our hospital were investigated. Anti-Scl70 antibody and anti-centromere antibody was also measured using conventional DID assay.
Results:
Serum from 80 SSc patients, 75 female and 5 male patients between 51.7±15.2 years old, were investigated. Eighty SSc patients consisted with 47 diffuse cutaneous SSc (dcSSc) type and 33 limited cutaneous SSc (lcSSc) type patients. Anti nuclear antibody positivity detected by indirect immunofluorescence methods was 92.5%. Higher total skin score (MRSS), complications of lung fibrosis, Raynaud’s phenomena, and arthritis were more frequently observed in dcSSc patients. Sensitivity and specificity of anti-Scl70 antibody using LBA was 90% and 92% respectively. Sensitivity and specificity of anti-centromere antibody using line assay was 87.5 % and 95.5% respectively. Sensitivity against both auto antibodies was much higher in LBA than DID method. Anti U3 RNP antibody, Anti NOR90 antibody and anti Ku antibody was also detected by LBA. Previous reports describe anti Th/To antibody were detected in 5-10 % of SSc patients by immunoprecipitation (IP) method. However, anti Th/To antibody was not detected in this screening using LBA.
We also investigated the relationship between appearance of auto antibody and clinical phenotypes. It is known anti RNA polymerase III antibody positivity correlates with rapid skin sclerosis and higher MRSS points. This correlation was also identical with our cohort study. Anti Ku antibody positivity is known to correlate with myositis and pulmonary hypertension. However, our analysis indicated anti Ku antibody positivity was only correlated with myositis not with pulmonary hypertension.
Conclusion:
Although the specificity of LBA was not better than conventional DID method, sensitivity was much higher than conventional DID assay. In case of anti Th/To antibody, none of sera showed positivity. Even though we have not evaluated anti Th/To antibody positivity by IP method, the frequency of anti Th/To antibody by LBA is much lower than previous report. Affinity to anti Th/To antibody by in this LBA may be affected by peptide design interfere conformation. Anti U3 RNP antibody, anti NOR90 and anti Ku antibody are usually detected by IP and western blot assay. These methods are complicated and not widely manipulated by commercial base laboratory. The LBA method provides more easy detection of auto antibody, and gives more beneficial information by measuring multiple parameters at once for characterization of SSc.
Disclosure:
K. Takagi,
None;
Y. Kawaguchi,
None;
S. Kataoka,
None;
Y. Ota,
None;
Y. Okamoto,
None;
M. Hanaoka,
None;
H. Ichida,
None;
T. Gono,
None;
Y. Katsumata,
None;
H. Yamanaka,
None.
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