Complexity and challenges in defining myeloid-derived suppressor cells.

Area of Science:

• Immunology
• Oncology
• Cell Biology

Background:

• Myeloid cells with suppressive activity, termed myeloid-derived suppressor cells (MDSCs), play a significant role in cancer by inhibiting the host's immune response.
• MDSC expansion is observed in various cancers in both patients and animal models, correlating with disease progression and decreased survival.

Purpose of the Study:

• To review the identification and phenotyping challenges of myeloid-derived suppressor cells (MDSCs).
• To discuss the importance of monitoring MDSC expansion in clinical settings.

Main Methods:

• Flow cytometry is the primary technique for identifying and quantifying MDSCs.
• Multicolor approaches are essential for accurate phenotyping due to MDSC heterogeneity.

Main Results:

• MDSCs are immature myeloid cells from monocytic and granulocytic lineages with varying differentiation stages.
• Tumor-derived soluble factors influence MDSC expansion and differentiation block.

Conclusions:

• Accurate phenotyping of MDSCs is critical for understanding their role in cancer.
• Addressing challenges in phenotyping circulating and tumor-associated MDSCs is vital for clinical applications.