Comparative Performance of Flow Cytometry and ELISA for Detecting Ki-67 and HLA-DR in Whole Blood: Implications for Tuberculosis Diagnosis and Treatment Monitoring

Background: This study aimed to compare the performance of flow cytometry and enzyme-linked immunosorbent assay (ELISA) in detecting Ki-67 and HLA-DR in whole blood from individuals with active TB, latent TB infection (LTBI), and healthy controls. Methods: A total of 60 participants were enrolled and categorized into three groups: active TB ( n = 20), LTBI ( n = 20), and healthy controls ( n = 20). Whole-blood samples were analyzed using flow cytometry for intracellular Ki-67 and surface HLA-DR expression in T cells, and ELISA for quantification of their soluble forms. Statistical comparisons were performed using ANOVA and Pearson correlation. Results: Flow cytometry revealed significantly elevated Ki-67 (12.4 ± 2.1%) and HLA-DR (18.7 ± 3.6%) expression in active TB compared to LTBI (5.6 ± 1.4%, 9.5 ± 2.1%) and controls (1.9 ± 0.7%, 3.2 ± 1.2%), respectively ( P < 0.001). ELISA also detected increased concentrations of both markers in active TB (Ki-67: 4.2 ± 1.1 ng/mL; HLA-DR: 6.8 ± 1.7 ng/mL) but with reduced sensitivity. A strong positive correlation was observed between flow cytometry and ELISA results for both biomarkers ( r > 0.75, P < 0.01). Conclusion: Flow cytometry offers high sensitivity for TB immune markers, while ELISA is a practical alternative. Ki-67 and HLA-DR are promising biomarkers for TB diagnosis and monitoring.