MAIT Cells in Tumor Contexts: Functional Diversity and Regulatory Hierarchies.

Mucosal associated constant T (MAIT) cells are a unique subset of innate T lymphocytes that play a critical role in the host's defense against bacterial and viral pathogens. However, its function in the tumor microenvironment (TME) remains controversial. This review systematically explores the dual role of MAIT cells in tumor immunity by integrating existing literature evidence, and proposes a three-level causal hierarchy that determines the functional fate of MAIT cells. In order to solve the prognostic paradox across cancer types, we introduced the barrier and systemic tumor classification criteria. Based on the above mechanisms, we explored clinical translation pathways such as MR1 targeted intervention, iPSC derived reMAIT cells, and CAR-MAIT engineering. Future research should utilize spatial omics and dynamic tracking techniques to achieve a shift from descriptive observations to precise predictive healthcare driven by biomarkers.