Value of T-SPOT.TB combined with IL-2, IFN-γ in diagnosis of active tuberculosis

OBJECTIVE To explore the value of tuberculosis infection T cell spot test (T-SPOT.TB) combined with cytokines interleukin-2 (IL-2), interferon-γ (IFN-γ) in differential diagnosis of active tuberculosis (ATB) and non-ATB.

METHODS A total of 186 patients with pulmonary tuberculosis (TB) who were treated in Hebei Provincial Chest Hospital from Feb. 2021 to Mar. 2024 were recruited as the research subjects and were divided into the ATB group with 92 cases and the non-ATB group with 94 cases according to the result of sputum culture for MTB, which was taken as the golden standard. The T-SPOT. TB was carried out for all of the subjects. The baseline data were collected from the two groups of patients. The hierarchical regression analysis was performed by setting the T-SPOT.TB, IL-2 and IFN-γ as the dependent variables, clinical symptoms of cough and fever as the independent variables. The impact of the clinical characteristics on T-SPOT.TB, IL-2 and IFN-γ was observed. The value of T-SPOT.TB combined with cytokines IL-2 and IFN-γ in differential diagnosis and ATB and non-ATB was evaluated by means of principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). The efficiencies of T-SPOT.TB, IL-2, IFN-γ and prediction model were examined by receiver operating characteristic (ROC) curves.

RESULTS There were significant differences in cough, fever, IL-1β, IL-2, IL-6, IL-8 and IFN-γ between the two groups(P < 0.05). There were statistically positive correlations between the clinical symptoms of cough, fever and the T-SPOT.TB, IL-2 and IFN-γ (P < 0.05). The result of PCA model and PLS-DA model showed that there were less significant individual differences between the ATB patients and the non-ATB patients, the two groups could be remarkably clustered and identified. The area under the curve (AUC) of the joint model was highest(0.913) (0.875 to 0.950) (P < 0.05), with the sensitivity 90.24%, the specificity 74.54%.

CONCLUSION The T-SPOT.TB combined with IFN-γ and IL-2 shows high sensitivity and specificity in differential diagnosis of ATB and non-ATB and can be used as method for auxiliary diagnosis of ATB, and it has significant clinical value.