Objective To investigate the cytokine levels and their clinical significance in patients with inflammatory bowel disease (IBD) complicated by active tuberculosis (ATB) following anti-tumor necrosis factor-α (TNF-α) therapy.

Methods A retrospective study was conducted in 92 patients with IBD complicated by latent tuberculosis infection. The patients were divided into observation group (37 cases) and control group (55 cases) based on whether they developed ATB. Enzyme-linked immunosorbent assay (ELISA) was used to measure serum cytokine levels, including interferon-γ (IFN-γ), interleukin-1 receptor antagonist (IL-1Ra), interleukin-2 (IL-2), interleukin-4 (IL-4), interleukin-10 (IL-10) and interleukin-17 (IL-17). Spearman correlation analysis was performed to evaluate the associations between cytokine levels and the risk of secondary ATB. Multivariate Logistic regression analysis was used to identify the influencing factors for development of ATB in IBD patients treated with anti-TNF-α therapy. Receiver operating characteristic (ROC) curves were plotted to evaluate the predictive value of cytokines for the development of ATB.

Results The levels of IFN-γ, IL-1Ra, IL-2 and IL-10 in the observation group were significantly higher than those in the control group (P < 0.05). The levels of IL-4 and IL-17 in the observation group were slightly higher than those in the control group, but the differences were not statistically significant (P>0.05). Positive correlations were observed between the levels of IFN-γ, IL-1Ra, IL-2 and IL-10 and the risk of secondary ATB (r=0.737, 0.586, 0.660 and 0.619, respectively; P < 0.05). Serum levels of IFN-γ, IL-1Ra, IL-2 and IL-10 were all independent influencing factors for the development of ATB in IBD patients treated with anti-TNF-α therapy (P < 0.05). ROC curve analysis revealed that the combination of IFN-γ, IL-1Ra and IL-10 had the highest predictive efficacy for the development of ATB in IBD patients treated with anti-TNF-α therapy, with an area under the curve of 0.996.

Conclusion The serum levels of IFN-γ, IL-1Ra, IL-2 and IL-10 are significantly elevated in IBD patients complicated by ATB following anti-TNF-α therapy. These cytokines are all independent influencing factors for the development of ATB, and the combination of IFN-γ, IL-1Ra and IL-10 demonstrates the highest predictive efficacy.