Multi-parameter flow cytometry immunophenotyping distinguishes different stages of tuberculosis infection

Area of Science:

• Immunology
• Infectious Diseases
• Biomarker Discovery

Background:

• Accurate diagnosis of active tuberculosis (TB) is crucial for effective treatment and control.
• Current diagnostic methods have limitations, necessitating the search for novel host biomarkers.
• Distinguishing active TB from latent TB infection (LTBI) and uninfected individuals is a diagnostic challenge.

Purpose of the Study:

• To identify novel host biomarkers in blood for differentiating active TB patients from uninfected (NoTBI) and latently infected contacts (LTBI).
• To evaluate the diagnostic accuracy of identified biomarkers using multi-parameter flow cytometry.

Main Methods:

• Blood cell counts were performed to analyze leukocyte populations.
• Peripheral blood mononuclear cells (PBMCs) were isolated for multi-parameter flow cytometry.
• Basal and Mycobacterium tuberculosis (Mtb)-stimulated lymphocyte distribution and expression were analyzed, with diagnostic accuracy assessed by Area Under the ROC Curve (AUC).

Main Results:

• Active TB patients showed significantly higher Monocyte-to-lymphocyte and Neutrophil-to-lymphocyte ratios (AUC >0.8).
• Differences in basal Th1/Th2 ratio, Th1-Th17, CD4+ Central Memory (TCM), and MAIT cells distinguished active TB from contact groups (AUC >0.7).
• Mtb-stimulated CD4+ TCM cells expressing CD154 demonstrated higher accuracy than IFNγ in discriminating Mtb-specific activation.

Conclusions:

• Specific leukocyte ratios and lymphocyte subsets serve as potential diagnostic biomarkers for tuberculosis.
• The distribution of CD4+ TCM cells and their CD154 expression post-Mtb activation are highly promising for TB diagnosis.