HEp2 ANA EIA: a new fully automated assay for the screening of antinuclearantibodies

Background: Screening for antinuclear antibodies is performed for various s ystemic autoimmune diseases with various different techniques. A more recen t approach to ANA screening is the use of enzyme immunoassays. Objectives: To introduce the new COBAS(R) CORE HEp2 ANA EIA, the first full y automated enzyme immunoassay for the detection of ANA in serum and plasma of patients with suspected systemic autoimmune,disease. Methods: A method comparison between the new HEp2 ANA EIA and immunofluores cence assays on HEp2 cells was performed in two groups - 977 patients with systemic autoimmune disorders and 952 healthy subjects with no autoimmune d isease-related diagnosis. Results: The clinical sensitivity in the patient group was 79.8% for HEp2 A NA EIA and 89.5% for IFA, and the clinical specificity in the control group was 91.7% for HEp2 ANA EIA and 93.9% for IFA. The analysis of 830 routine samples showed an overall good concordance of 85% between both assays. Furt her examination of the discrepant results showed 8% discrepant negative res ults for the Hep2 ANA EIA assay compared to 21% for IFA. Discrepant positiv e results were found in 37.9% and 33% of samples for the HEp2 ANA EIA and t he IFA, respectively. Conclusion: The HEp2 ANA EIA is the first fully automated assay for the det ection of ANA in serum and plasma. The assay shows improved sensitivity in ANA determination and a similar performance, compared to the standard metho d of IFA.