Publication date: Aug 01, 2024

The interferon-gamma (IFN-γ) release assay (IGRA) is an important laboratory diagnosis for latent Mycobacterium tuberculosis (TB) infection. The TB-IGRA measures the release of IFN-γ from peripheral blood cells, who are exposed to TB antigen (Ag), mitogen (MT), or negative/nil control (NL) in vitro. While, an exceptional higher TB Ag-NL level will reflect an elevation of peripheral lymphocytes released IFN-γ in a same condition. Therefore, we found that the elevated levels of TB Ag-NL could become a new biomarker for the diagnosis and treatment of pediatric systemic lupus erythematosus (SLE) patients. We have analyzed the clinical data of 776 children who are underwent TB-IGRA testing in the Department of Allergy and Rheumatology of Guangzhou Women and Children’s Medical Center from 2018 to 2020. To investigate the association between TB Ag-NL and SLE, we have analyzed the clinical data of 47 SLE patients and TB Ag-NL testing results, and then evaluated the association between TB Ag-NL and SLE disease activity. The TB Ag-NL levels were significantly higher in patients with active SLE than those in inactive SLE (p = 0. 0002). The TB Ag-NL levels were positively correlated with the SLE disease activity index (SLEDAI) and laboratory diagnosis parameters. The mean value of TB Ag-NL in SLE patients (0. 04191 +/- 0. 07955, IU/mL) were significantly higher than those in patients with juvenile dermatomyositis (JDM) (0. 0158 +/- 0. 0337, IU/mL, p = 0. 036), juvenile idiopathic arthritis (JIA) (0. 0162 +/- 0. 0388, IU/mL, p = 0. 001), and healthy controls (HC) (0. 0001 +/- 0. 0027, IU/mL, p = 0. 0003). Therefore, the elevated TB Ag-NL levels could serve as a potential diagnostic biomarker of SLE, especially for the active SLE. The detection of IFN-γ release levels by the TB-IGRA may be useful to assess SLE disease activity in pediatric patients with active SLE.

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