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

ABSTRACT

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.