Delayed-Type Hypersensitivity to Mycobacterium tuberculosis Antigens: The Immunological Mechanism and Potential Therapeutic Strategies—A Systematic Review

Delayed-type hypersensitivity (DTH) to <i>Mycobacterium tuberculosis</i> (MTb) antigens is a crucial component of the cellular immune response presented during tuberculosis infection. This reaction is driven primarily by T lymphocytes, which recognize mycobacterial antigens and trigger a focused inflammatory cascade. Cytokines produced by T lymphocytes stimulate the formation of granulomas, organized structures that help contain the bacteria and prevent their spread. DTH is essential for controlling the infection and forms the basis of diagnostic tools, including the still widely practiced tuberculin skin test despite its limitations. This immunological mechanism is also used as an important therapeutic target in the treatment of tuberculosis by modulating the cellular response. These approaches include immunomodulatory agents, therapeutic vaccines and host-directed treatment. Ongoing research offers promising opportunities for future interventions aimed at decreasing the global mortality associated with tuberculosis.