Purpose: Highly active systemic lupus erythematosus (SLE) causes a high risk of tuberculosis (TB) infection in SLE patients in Indonesia, a country in which the disease, especially extrapulmonary TB, is endemic. Interferon (IFN)-γ releasing assay (IGRA) can detect latent or previous TB infection. This study sought to determine latent TB infection and levels of IFN-γ, a key player in various inflammation and autoimmune disease, in patients with SLE and relate findings to disease activity.
Patients and methods: This experimental study included 79 female subjects distributed into three groups of active SLE, quiescent SLE and healthy controls. We used SLE Disease Activity Index-2000 (SLEDAI-2K) scores to stratify the subjects. Each group underwent IGRA testing using the QuantiFERON-TB Gold Plus kit.
Results: We recruited 59 female patients with SLE. The patients had a median age and disease duration 30 and 5 years, respectively. Statistical analysis using the Kruskal-Wallis test showed that active condition, high SLEDAI-2K score and immunosuppressive therapies affect IGRA results. Specifically, healthy controls (n=20) were most likely to have negative IGRA results (67.09%), whilst 27.27% of active cases (n=33) and 3.85% of quiescent cases (n=26) had indeterminate results (p=0.02). The number of immunosuppressant therapies was significantly negatively correlated with IFN-γ (p=0.004). No difference in IFN-γ concentration was detected amongst the active and other groups (p>0.05).
Conclusion: High-activity SLE and immunosuppressive therapies cause dysregulation of the immune response, which, in turn, influences IGRA results. Thus, additional testing is necessary to detect TB infection in patients with SLE.
Keywords: IFN-γ; IGRA; SLE; active; quiescent.
© 2020 Maharani et al.