Comparative study for detection of antinuclear antibodies by ELISA and Immunoflourescent techniques

Background: Antinuclear antibodies frequently arise in the sera of patients with connective tissue disease, including systemic lupus erythematosus, rheumatoid arthritis. Their serum presence is included in the classification criteria for systemic lupus erythematosus of the American College of Rheumatology. However, antinuclear antibodies can also be found in the absence of autoimmune diseases including various types of infections. The aim of this study: was to analyze antinuclear antibody screening by enzyme-linked immunosorbent assay (ELISA) followed by indirect fluorescent antibody assay testing to confirm and characterize and to compare the sensitivities of enzyme-linked immunosorbent assay and indirect fluorescent antibody testing for detection of antinuclear antibody. Results: Only one out of the 50 samples from apparently healthy adults had a positive antinuclear antibodies result by the indirect immunofluorescence assay test (99.5% specificity). However, Aesku, and INOVA ELISAs demonstrated specificities of 95%, and 85%, respectively, in the healthy serum samples when compared with indirect immunofluorescence assay results as the standard. Also sensitivities of enzyme-linked immunosorbent assay and indirect fluorescent antibody assay testing using clinically defined serum samples demonstrated that in case of systemic lupus erythematosus patients, Aesku, and INOVA antinuclear antibodies ELISAs demonstrated excellent screening sensitivities of 92.8% and 91.6%, respectively compared with antinuclear antibodies by indirect immunofluorescence assay test which had only 75% sensitivity. The antinuclear antibodies ELISAs, Aesku, and INOVA, detected 45%, and 52% positives, respectively in those clinically diagnosed as rheumatoid arthritis patients compared with less sensitive indirect immunofluorescence assay test , which detected only(30%) positive samples for antinuclear antibodies. Conclusion: The results proved that ELISA system is more sensitive for detection of antinuclear antibodies compared with indirect immunofluorescence assay test. Recommendation: Our data support the routine use of antinuclear antibodies ELISA screening of patients suspected of having autoimmune diseases of the connective tissue followed by indirect immunofluorescence assays on positive samples for confirmation of antibodies, pattern, and titer.