Immune system (intravesical immunostimulation)

Intravesical immunostimulation is a therapeutic strategy primarily used in the treatment of non-muscle invasive bladder cancer (NMIBC) to eradicate residual tumor cells and prevent recurrence. This approach typically involves the administration of Bacillus Calmette-Guérin (BCG), a live attenuated strain of Mycobacterium bovis, directly into the bladder via a catheter [PMID: 32835118]. The mechanism of action relies on the induction of a robust, localized inflammatory response characterized by the recruitment of various immune cells, including macrophages, neutrophils, and T lymphocytes, to the bladder wall [PMID: 28611161]. Upon attachment to the urothelium through fibronectin, BCG is internalized by both normal and malignant cells, triggering the release of Th1-type cytokines such as interferon-gamma and interleukin-12 [PMID: 11516513]. These cytokines activate cytotoxic T cells and natural killer cells, which then target and destroy cancer cells through direct contact and the release of perforins and granzymes [PMID: 25633155]. While this method is the gold standard for high-risk NMIBC, it is associated with significant side effects ranging from local cystitis to life-threatening systemic BCG infection [PMID: 30855618].

Other names

BCG immunotherapyIntravesical BCG therapyBladder immune microenvironmentLocal bladder immunostimulationIntravesical infection-mediated immunity

Induction of a localized Th1-polarized immune response through the recruitment and activation of macrophages, natural killer cells, and cytotoxic T lymphocytes following urothelial attachment and internalization of immunostimulatory agents.