Combined Detection of IFN-γ And CD64 for Diagnosis and Monitoring of Active Pulmonary Tuberculosis in Elderly Patients

This study assessed the risk of active pulmonary tuberculosis (ATB) in elderly patients with weakened immunity by jointly detecting serum interferon-γ (IFN-γ) and neutrophil CD64, and analyzed the impact of this diagnostic protocol on the course of ATB. A total of 50 patients with ATB and 50 age- and sex-matched healthy controls were recruited. Subsequently, the patient's neutrophil CD64 (quantified as the percentage of CD64-positive neutrophils [CD64%]), IFN-γ (by enzyme-linked immunosorbent assay [ELISA]), C-reactive protein (CRP; by immunoturbidimetry), and erythrocyte sedimentation rate (ESR; by Westergren method). Sputum samples from patients were cultured on Löwenstein-Jensen (L-J) medium and in the MGIT 960 automated system. The diagnostic efficacy of individual and combined biomarkers was assessed with receiver operating characteristic (ROC) curve analysis, and a logistic regression model was developed for combined detection. Significantly elevated levels of both IFN-γ and CD64 were observed in ATB patients versus healthy controls (P<0.05). A diagnostic model incorporating both biomarkers had an area under the curve (AUC) of 0.838, with a sensitivity of 84.00% and a specificity of 76.00%. Both markers decreased following therapeutic intervention (P<0.05), showing the lowest values in culture-negative patients (P<0.05). Furthermore, the combined model showed predictive utility for culture conversion, attaining an AUC of 0.756 (65.71% sensitivity, 80.00% specificity; P<0.001). The combined detection of IFN-γ and CD64 can effectively diagnose the occurrence of ATB in immunocompromised elderly people, providing a reference for clinical practice.