Validation of a new immunoenzymatic method to detect antibodies to RNA polymerase III in systemic sclerosis

• Published in: Clinical and experimental rheumatology Vol. 25; no. 3; pp. 373 - 377
• Main Authors: CODULLO, V, MOROZZI, G, VALESINI, G, MONTECUCCO, C, BARDONI, A, SALVINI, R, DELEONARDI, G, DE PITA, O, RICCIERI, V, RUFFATTI, A, TINCANI, A, TOZZOLI, R
• Format: Journal Article
• Language: English
• Published: Pisa Clinical and Experimental Rheumatology 01.05.2007
• Subjects: Adult; Aged; Aged, 80 and over; Antibodies - blood; Biological and medical sciences; Enzyme-Linked Immunosorbent Assay - methods; Humans; Immunoprecipitation - methods; Italy; Medical sciences; Middle Aged; Reference Values; Reproducibility of Results; RNA Polymerase III - immunology; ROC Curve; Sarcoidosis. Granulomatous diseases of unproved etiology. Connective tissue diseases. Elastic tissue diseases. Vasculitis; Scleroderma, Systemic - blood; Scleroderma, Systemic - ethnology; Scleroderma, Systemic - immunology; Sensitivity and Specificity; Autoimmunity; Immunopathology; Connective tissue disease; Skin disease; RNA; Antibody; Autoantibody; Autoimmune disease; systemic sclerosis; Systemic disease; anti-RNA polymerases antibodies; Scleroderma; autoantibodies
• ISSN: 0392-856X

To test the reliability of a new enzyme-linked immunosorbent assay (ELISA) to identify anti-RNA polymerase III (RNAP III) positive sera from Italian patients with Systemic Sclerosis (SSc) and other chronic inflammatory disorders. A comparison between the new ELISA for anti-RNAP III and the gold standard technique, immunoprecipitation (IP), was first performed on 106 SSc patients, 16 patients with other connective tissue diseases and 10 healthy subjects. A further ELISA evaluation was performed on 224 SSc patients, 120 subjects with other rheumatic or infectious diseases, and 81 healthy controls. Plotting ELISA and IP data in a Receiver Operator Characteristic curve, the ELISA cut-off value providing the best specificity (99.1%) and sensibility (100%) was 28 U/ml (AUC=0.999; p<0.0001). Using this cut-off in the second analysis, anti-RNAP III positive results were found in 41 (18.3%) SSc patients, all negative for anticentromere or anti-topoisomerase I antibodies, while only 3 subjects tested positive among the 120 sera collected from other patients. All the healthy subjects were negative. This new ELISA for anti-RNAP III is highly accurate when a proper cut-off value is employed and represents a valid substitute to IP in a clinical setting.