Persistent expression of activation markers on Mycobacterium tuberculosis-specific CD4 T cells in smear negative TB patients.

Background: T cell activation (HLA-DR, CD-38), proliferation (KI-67), and functional (IFN-γ, TNF-α) markers have recently been shown to be useful in predicting and monitoring anti-TB responses in smear positive TB, but previous research did not characterize the activation and proliferation profiles after therapy of smear negative TB.

Methodology: In this study, we used polychromatic flow cytometry to assess selected PPD-specific T cell markers using fresh PBMC of smear negative and positive pulmonary tuberculosis (PTB) patients, recruited from health facilities in Addis Ababa.

Result: Levels of activation (HLA-DR, CD38) and proliferation (Ki-67) among total unstimulated CD4 T cells decreased significantly after therapy, particularly at month 6.

Mycobacterium tuberculosis antigen-specific T-cell responses in smear-negative pulmonary tuberculosis patients.

Despite recent improvements in microbial detection, smear-negative TB remains a diagnostic challenge. In this study, we investigated the potential discriminatory role of polychromatic flow cytometry of M. tuberculosis antigen-specific T cells to discriminate smear-negative TB from health controls with or without latent TB infection, and non-TB respiratory illnesses in an endemic setting.