Mycobacterium tuberculosis PPD-specific CD4+ T cell

Antigen-specific CD4+ T cells recognizing Mycobacterium tuberculosis (Mtb) Purified Protein Derivative (PPD) peptides are a critical component of the adaptive immune response against tuberculosis (Jasenosky et al., 2015). These cells express T-cell receptors (TCRs) that specifically bind to mycobacterial peptides presented by Major Histocompatibility Complex (MHC) class II molecules on the surface of professional antigen-presenting cells (Scriba et al., 2017). Upon activation, these CD4+ T cells proliferate and secrete pro-inflammatory cytokines, most notably interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α), which are essential for activating macrophages to kill intracellular Mtb (O'Garra et al., 2013). In the context of disease, these cells are central to both the containment of latent infection and the immunopathology associated with active tuberculosis (Pai et al., 2016). They are the primary target of the Bacillus Calmette-Guérin (BCG) vaccine and various novel subunit vaccines, such as M72/AS01E, designed to enhance protective immunity (Tait et al., 2019). Additionally, their reactivity is the basis for diagnostic tools like the tuberculin skin test (TST) and interferon-gamma release assays (IGRAs) (Pai et al., 2014). Therapeutic strategies often aim to modulate the frequency and functional profile of these cells to improve clinical outcomes in tuberculosis patients (Andersen & Scriba, 2019).

Other names

PPD-specific CD4+ T cellsTuberculin-reactive CD4+ T cellsMtb-specific CD4+ T lymphocytesAntigen-specific CD4+ T cells recognizing Mycobacterium tuberculosis PPD peptides presented on MHC class II

Vaccines and diagnostic antigens trigger the activation, proliferation, and cytokine production of these cells by providing specific peptide-MHC class II ligands for T-cell receptor engagement.