Diagnostic value of Immunobloting assay for determination of anti nuclear antibody (ANA) in rheumatic diseases

Abstract

In this study we compare three techniques (IF, IB, ELISA) in detection of ANA. If the sensitivity and specificity of IB superior to other methods, we can replase IF and ELISA with IB. We evaluate correlation between anti ribosomal-P antibody and type of the disease. Also we evaluate correlation between anti- nucleosome and lupus nephritis.

Methods: An analytical cross-sectional study of 90 sera from patients with SLE, SSc and DM was undertaken. Sera collected and stored at -80˚c. Then they were used to detection of ANA with three techniques.

Results: 63 (74.1) of all were ELISA positive and 22 (25.9) had negative ELISA. 74 (87.1) IF positive and 11 (12.9) IF negative were observed. 74 (87.1) of patients were IB positive and 11 (12.9) had negative IB. Anti ribosomal-P antibody was positive in 15 (20.3) of SLE patients. 14 (82.4) sera from 17 patients with lupus nephritis were positive for anti-nucleosome antibody and 3 of them (17.6) were negative. The sensitivity and specificity of IB in comparison with IF was 98.65% and 90.91% respectively. In comparison with ELISA we found 93.65% and 31.82% of sensitivity and specificity. There was no correlation between anti ribosomal-P antibody and SLE patients. (P=0.1) We found correlation between anti-nucleosome antibody and lupus nephritis. (P<0.0001)