Antigen-Specific Th1 Cytokine Markers and Protection Against Tuberculosis: A Systematic Review and Meta-analysis Stratified by Progression to Active Disease and Sustained IGRA Conversion

Intervention: Measurement of antigen-specific Th1 cytokine responses (e.g., IFN-γ, IL-2, TNF-α) to TBrelated antigens such as PPD, Ag85A, ESAT-6, or other vaccine antigens (BCG, M72/AS01E, MVA85A).Comparison: Studies comparing the presence or magnitude of these cytokine markers between those who progress to active TB disease and those who do not, as well as comparisons between those with sustained IGRA conversion (immune response markers) and non-converters.Outcome: The primary outcome is progression to active TB disease, while the secondary outcome includes sustained IGRA conversion, a surrogate for exposure to TB.These outcomes assess the relationship between Th1 cytokine markers and disease risk or immune activation.Study design: Randomized controlled trials (RCTs), prospective cohort studies, and observational studies with longitudinal follow-up, focusing on immune correlates in the context of vaccine trials or natural TB exposure.Condition being studied TB spreads through the air when an infected person coughs, sneezes, or talks.It is classified into two forms: Latent TB: In this form, the person is infected with M. tuberculosis but does not have active disease.