Exploration of the diagnostic value and expression levels of IFN-γ and IL-2 in patients with lymph node tuberculosis

Lymph node tuberculosis (LNTB) is the most common form of extrapulmonary tuberculosis (TB). The symptoms of LNTB lack specificity, making diagnosis difficult and increasing the likelihood of missed or incorrect diagnoses. Along with IFN-γ Release Assay (IGRA), the detection method using enzyme-linked immunosorbent assay (ELISA) can simultaneously detect IFN-γ and interleukin-2 (IL-2). However, the diagnostic value and expression levels of IFN-γ and IL-2 in patients with LNTB remain unclear.

A total of 95 patients with enlarged lymph nodes were enrolled. Baseline data were collected, including age, gender, history of TB, histopathology, microbiology test results, and blood levels of IFN-γ and IL-2. Receiver operating characteristic (ROC) curve was used to investigate the diagnostic effect of the IFN-γ and IL-2. A double antibody sandwich ELISA was used to detect the concentrations of IFN-γ and IL-2 in culture supernatants.

Based on ROC curves, the cut-off values for IFN-γ/IL-2 for differentiating LNTB from non-TB-lymphadenopathy (LAP) were determined to be 58.267 and 12.207 pg/mL, respectively. In patients with LNTB and non-TB-LAP, the sensitivity of IFN-γ/IL-2 in parallel was 83.33% (95% CI: 71.71-90.99), significantly higher (p < 0.05) than that for IFN-γ alone. The highest specificity (93.10%) (95% CI: 75.78-98.8) was observed when IFN-γ and IL-2 were applied in tandem.

The combined detection of IFN-γ and IL-2 showed good diagnostic efficacy in LNTB. In addition, in patients diagnosed with LNTB, the expression level of IL-2 may be related to the burden of MTB and the severity of TB infection.