Antibodies to fibrillarin, PM-Scl and RNA polymerase III detected by ELISA assays in patients with systemic sclerosis.
BACKGROUND
Anti-fibrillarin (AFA), anti-RNA polymerase (anti-RNAP), and anti-PM-Scl autoantibodies are useful markers for the diagnosis of systemic sclerosis (SSc) in patients who are anti-centromere- (ACA) or anti-topoisomerase I (anti-topo I)-negative, but, until recently, the only specific method for their identification was the radio-immunoprecipitation assay. The aim of this study was to evaluate the clinical accuracy of the new enzyme-linked immunosorbent assays (ELISA) developed by Phadia for their detection.


METHODS
Sera of 50 ACA and anti-topo I-negative SSc patients, and, as control group, sera of 122 patients (42 with SSc, ACA or anti-topo I-positive, 40 with systemic lupus erythematosus and 40 with rheumatoid arthritis) were studied.


RESULTS
Using the cutoff proposed by the manufacturer (10 AU/mL), sensitivity and specificity were: for AFA, 22% and 92.6%; for anti-RNAP, 16% and 97.5%; and for anti-PM-Scl, 8% and 98.8%, respectively. Using a cutoff corresponding to 98.8% specificity for all three antibodies, sensitivity was 10%, 14% and 8%, respectively. The combined use of these three antibody assays enabled identification of 32% of ACA- and anti-topo I-negative SSc patients.


CONCLUSIONS
These new ELISA methods for AFA, anti-RNAP III and anti-PM-Scl detection have good diagnostic specificity, and may help identify a subset of SSc patients ACA and anti-topo I-negative.
Villalta
Danilo
D
Allergologia e Immunologia Clinica, DML, A.O. S. Maria degli Angeli, Pordenone, Italy. danilo.villalta@aopn.fvg.it
Morozzi
Gabriella
G
Tampoia
Marilina
M
Alpini
Claudia
C
Brusca
Ignazio
I
Salgarolo
Valeria
V
Papisch
Wolfgang
W
Bizzaro
Nicola
N
D001323:Autoantibodies / Q000097:blood / Q000276:immunology*; D001324:Autoantigens / Q000276:immunology*; D002868:Chromosomal Proteins, Non-Histone / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005095:Exoribonucleases / Q000276:immunology*; D063326:Exosome Multienzyme Ribonuclease Complex; D006801:Humans; D009687:Nuclear Proteins / Q000276:immunology*; D012320:RNA Polymerase III / Q000276:immunology*; D012595:Scleroderma, Systemic / Q000175:diagnosis* / Q000276:immunology*; D012680:Sensitivity and Specificity
D001323:Autoantibodies; D001324:Autoantigens; D002868:Chromosomal Proteins, Non-Histone; D009687:Nuclear Proteins; C047458:fibrillarin; D012320:RNA Polymerase III; D005095:Exoribonucleases; D063326:Exosome Multienzyme Ribonuclease Complex; C077044:EXOSC10 protein, human