Changes in the result of antinuclear antibody immunofluorescence assay on HEp-2 cells reflect disease activity status in systemic lupus erythematosus

Background The objective of the study was to determine whether the staining pattern and titer of indirect immunofluorescence assay on HEp-2 cells (HEp-2 IFA) are associated with systemic lupus erythematosus (SLE) disease activity. Methods A total of 269 consecutive patients meeting the ACR and SLICC criteria for SLE were classified into three groups according to the SLE Disease Activity Index 2000 (SLEDAI2K): Remission (SLEDAI2K = 0; n = 47); Intermediate (SLEDAI2K = 1-5; n = 111); Active (SLEDAI2K ≥ 6; n = 111). All subjects were assessed for HEp-2 IFA titer and staining pattern and nine traditional parameters of SLE disease activity. After a 6 to 12-month interval, 101 of the 269 patients were reassessed. Results HEp-2 IFA homogeneous nuclear pattern (AC-1) occurred more frequently in the Active Group compared to the Remission Group (p < 0.001). Fine speckled nuclear pattern (AC-4) tended to occur more frequently in the Remission Group compared to the Active Group (p = 0.054). Subjects with AC-1 pattern had higher SLEDAI (8.8 ± 7.6) than those with AC-4 (4.8 ± 5.2) (p < 0.001). HEp-2 IFA titer and anti-nuclear antibody by enzyme-linked immunosorbent assay (ANA-ELISA) values were lower in the Remission Group compared to the other two groups (p < 0.001). Multivariate analyses identified only ELISA anti-dsDNA as an independent variable associated with disease activity. In follow-up analysis, HEp-2 IFA titer decreased significantly in the 33 subjects with decreased disease activity (p = 0.002). Receiver operator characteristic (ROC) curve analysis for determination of disease activity showed equivalent areas under the curve (AUC) for HEp-2 IFA titer and traditional disease activity parameters. Conclusions HEp-2 IFA pattern and titer can reflect SLE disease activity and may be considered in conjunction with other laboratory and clinical parameters in the assessment of SLE disease activity.