Specific detection of anti-Th/To and U3RNP antibodies by IP-qPCR assay. A, B. Sera with antibodies to Th/To (n = 22), U3RNP (n = 12), TMG (n = 3), La (n = 12), topo I (n = 20), RNAPIII (n = 18), ACA (n = 15), PM-Scl (n = 5), and normal human sera (NHS, n= 15) were tested by the IP-qPCR method. Data points and median bar are representative of at least two independent experiments. P < 0.05 by Kruskal-Wallis and Dunn's multiple comparison tests was present among all the groups, with the exception of the anti-U3RNP/anti-TMG groups (P = ns). The cut-off was determined by ROC curve and positive range is shown as shaded areas. ACA, anti-centromere antibodies; IP-qPCR, immunoprecipitation-quantitative polymerase chain reaction; NHS, normal human serum; RNAPIII, RNA polymerase III; ROC curve, receiver operating characteristic curve; TMG, trimethylguanosine; topo I, topoisomerase I.