Clinical usefulness of anti-RNA polymerase III antibody measurement by enzyme-linked immunosorbent assay.
OBJECTIVE
To evaluate the clinical usefulness of measuring anti-RNA polymerase (RNAP) III antibody with a commercially available ELISA in Japanese patients with SSc.


METHODS
This multicentre study involved 354 patients with SSc, 245 with non-SSc CTDs and 102 healthy controls. ELISAs were used to detect anti-RNAP III antibody, anti-topo I antibody and ACA. The presence of anti-RNAP III antibody in selected serum samples was confirmed by immunoprecipitation (IP) assay.


RESULTS
By ELISA, anti-RNAP III antibody was detected in 38 (10.7%) patients with SSc, 3 (1.2%) with non-SSc CTD and no healthy controls. The clinical specificity for SSc was excellent (98.8%), although a small number of false positives occurred. The sensitivity of the anti-topo I and ACA ELISAs for SSc was 59.9%, which increased to 68.2% without a reduction in specificity when the anti-RNAP III measurement was added. Clinical features associated with positivity for the anti-RNAP III antibody include dcSSc, a high total skin score and a trend towards high prevalence of renal crisis, consistent with previous studies that used an IP assay. Furthermore, on clinical severity scales, SSc patients with anti-RNAP III antibody scored highest for skin and renal involvement among patients subgrouped by the presence of individual SSc-related antibodies.


CONCLUSIONS
The measurement of anti-RNAP III antibody by ELISA is useful in routine clinical practice, because it helps diagnose SSc and identify a disease subset with severe skin and renal involvement.
Satoh
Takashi
T
Department of Internal Medicine, Division of Rheumatology, Keio University School of Medicine, Tokyo 160-8582, Japan.
Ishikawa
Osamu
O
Ihn
Hironobu
H
Endo
Hirahito
H
Kawaguchi
Yasushi
Y
Sasaki
Tetsuo
T
Goto
Daisuke
D
Takahashi
Kazuo
K
Takahashi
Hiroki
H
Misaki
Yoshikata
Y
Mimori
Tsuneyo
T
Muro
Yoshinao
Y
Yazawa
Norihito
N
Sato
Shinichi
S
Takehara
Kazuhiko
K
Kuwana
Masataka
M
D000328:Adult; D000368:Aged; D000974:Antibodies, Antinuclear / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D003240:Connective Tissue Diseases / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006801:Humans; D047468:Immunoprecipitation; D008297:Male; D008875:Middle Aged; D012320:RNA Polymerase III / Q000276:immunology*; D012595:Scleroderma, Systemic / Q000175:diagnosis* / Q000276:immunology; D012720:Severity of Illness Index
D000974:Antibodies, Antinuclear; D015415:Biomarkers; D012320:RNA Polymerase III