Single-cell mass cytometry reveals distinct immune signatures in colorectal cancer.

Colorectal cancer (CRC) is one of the most frequent malignancies and the second leading cause of death from cancer worldwide. Studies have revealed that there are connections between inflammation and cancer. However, the exact immune cell composition and the alterations in adenoma and CRC remain unclear. In this study, we aimed to characterize the immunophenotypic shifts occurring during CRC progression through peripheral blood-based analysis. Mass cytometry (CyTOF) enables the simultaneous quantification of >50 cellular parameters with minimal overlap, overcoming the limitations of traditional flow cytometry and providing unprecedented insights into cellular heterogeneity. Utilizing the high-parameter capacity of CyTOF, we analyzed 31 untreated samples (from healthy donors, adenoma patients, and CRC patients) to uncover disease-specific immune signatures. A comparative analysis of immunophenotypic profiles across the three groups revealed distinct disease-associated trajectories. Key findings demonstrated progressive dysregulation in granulocytes during CRC progression, alongside altered B cell differentiation patterns. T-cell compartment showed CRC-specific changes: the CCR4+ and CXCR3+ central memory T cells decreased, CCR4+ double-negative T cells increased, and CD8+ T cells acquired an exhausted phenotype. Furthermore, NK cell functional heterogeneity was driven by the transition from HD/Adenomas to CRC. These immunophenotypic shifts collectively highlight the potential of CyTOF as a diagnostic platform for early CRC detection and monitoring through peripheral blood analysis.