Myeloid antigen-presenting cell niches sustain antitumor T cells and license PD-1 blockade via CD28 costimulation.

ABSTRACT: The mechanisms regulating exhaustion of tumor-infiltrating lymphocytes (TIL) and responsiveness to PD-1 blockade remain partly unknown. In human ovarian cancer, we show that tumor-specific CD8⁺ TIL accumulate in tumor islets, where they engage antigen and upregulate PD-1, which restrains their functions. Intraepithelial PD-1⁺CD8⁺ TIL can be, however, polyfunctional. PD-1⁺ TIL indeed exhibit a continuum of exhaustion states, with variable levels of CD28 costimulation, which is provided by antigen-presenting cells (APC) in intraepithelial tumor myeloid niches. CD28 costimulation is associated with improved effector fitness of exhausted CD8⁺ TIL and is required for their activation upon PD-1 blockade, which also requires tumor myeloid APC

SUBMITTER: Duraiswamy J 

PROVIDER: S-EPMC8861565 | biostudies-literature | 2021 Dec

REPOSITORIES: biostudies-literature