Objective: The indirect immunofluorescence (IIF) antibody method using HEp-2 cells for anti-nuclear antibodies (ANA) screening is the gold standard. Some antigens have been purified and termed as extractable anti-nuclear antibodies (ENA) to detect the autoantibodies. These autoantibodies are usually detected by the immunoblot (IB) method. In this study, we compared the ANA patterns detected by the IIF method with the ENA detected by IB to predict which confirmatory test should be selected for which ANA patterns.
Methods: 2894 serum samples sent from different clinics to both ANA and IB between January 2019 and March 2022 were analyzed in the Medical Microbiology Laboratory of University of Health Sciences Turkey İzmir Tepecik Education and Research Hospital.
Results: The ENA positivity rates of samples with positive ANA patterns were centromere 91%, Topo I-like 83%, speckled 66%, homogeneous with other ANA patterns 53%, speckled with other ANA patterns 53%, homogeneous 45%, nucleolar 30%, nuclear dots 28%, nuclear envelope 15%, and dense fine speckled-70 (DFS70) 10%, respectively. In the study, 100 (12.9%) of the clinical specimens with ANA positivity were sent from male patients and 674 (87.1%) from female patients, and the mean age was 43±19.17 years (age range: 0-88).
Conclusion: Our data are highly consistent with the centromere, Topo I-like, and granular patterns in IIF between specific antibody positivity detected in IB for antibodies associated with the pathogenesis of systemic autoimmune rheumatic diseases. We believe that the tests can be used more efficiently with rational laboratory use and can provide more accurate guidance to the clinic.