Background/Purpose: Antinuclear antibody (ANA) indirect immunofluorescence (IIF) assay on HEp-2 cells (HEp-2-ANA) is an important element for diagnosis and classification of Systemic Lupus Erythematosus (SLE), but is not considered as a parameter for monitoring disease activity. The objective was to determine whether HEp-2-ANA pattern and titer can be relevant for monitoring SLE disease activity.

Methods: 269 patients meeting the ACR criteria for SLE were consecutively retrieved during a one-year interval and classified into 3 groups according to SLEDAI2K: Remission Group (SLEDAI2K=0); Intermediate Group (SLEDAI2K=1-5); Active Group (SLEDAI2K≥6). In addition to HEp-2-ANA titer and pattern, the following putative parameters of disease activity were determined: 1) serum CH100, C3, C4 and C2; and 2) antibodies to native DNA, denatured DNA, C1q, and nucleosome. 101 of the 269 patients were prospectively reassessed after a six-month interval.

Results: there were 256 women and 13 men (37±11.4 years old) with disease duration of 9.3±7.5 years. Active (n=111), Intermediate (n=111) and Remission (n=47) groups did not differ in age, disease duration and gender. As expected, putative parameters of disease activity differed significantly among the 3 groups, indicating that they actually represent three different disease activity stages. Ten patients were ANA-negative (3.7%), equally distributed among the 3 groups (p=0.534). The nuclear homogeneous pattern (HO) occurred in 57 patients (51.4%) of the Active group and in 11 patients (23.4%) of the Remission group (p=0.003). The nuclear fine speckled pattern (FSp) occurred in 19 patients (40.4%) of the Remission group and in 25 patients (22.5%) of the Active group (p=0.09). Patients with HO pattern had higher SLEDAI (9.2±7.9) than those with FSp pattern (4.8±5.2) (p=0.008). ANA titer was lower in the Remission group (median 1/640) in comparison with the Active (median 1/2560) and Intermediate (median1/1280) groups (p<0.001). In the follow-up analysis, 50 patients remained in the same group (SLEDAI2K change ≤3) and 51 changed disease activity status (SLEDAI2K change ≥4). ANA titer decreased significantly in the 33 patients with decreasing disease activity (p=0.002) but not in the 50 patients with irrelevant change in SLEDAI2K (p=0.677) and in the 18 patients with increasing SLEDAI2K (p=0.080). ROC curve analysis for determination of disease activity showed equivalent areas under the curve (AUC) for ANA titer and all putative disease activity parameters.

Conclusion: ANA pattern and titer are affected by SLE disease activity and can be considered in conjunction with other laboratory and clinical parameters in the assessment of SLE disease activity.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/immunofluorescence-pattern-and-titer-of-the-antinuclear-antibody-test-correlate-with-disease-activity-in-patients-with-systemic-lupus-erythematosus/