Comprehensive single-cell analysis reveals mast cells' roles in cancer immunity.

Mast cells, traditionally known for their roles in allergic reactions and pathogen defense, have been revealed to possess significant functional diversity within the tumor microenvironment (TME). Through single-cell RNA sequencing analysis across 15 solid tumors (385 samples from 264 patients), 10 distinct mast cell states characterized by unique gene expression patterns and functional attributes were identified. Notably, the C7-HLA-DR cluster that closely linked with antigen presentation, has emerged as a key player in shaping anti-tumor immune responses. In this study, systematic analysis demonstrated that the C7-HLA-DR cluster could interact with T cells to enhance the efficacy of immunotherapy and improve patients' prognosis. On the contrary, the C1-HSPA1 cluster exhibited pro-tumor characteristics, highlighting the functional diversity of mast cells within TME. These findings illustrate the landscape of mast cell within TME and propose a new avenue to boost the efficacy of immunotherapy.