Diving Deep: Profiling Exhausted T Cells in the Tumor Microenvironment Using Spectral Flow Cytometry.

Area of Science:

• Immunology
• Cancer Biology
• Biotechnology

Background:

• Tumor microenvironment (TME) characterization is crucial for developing cancer immunotherapies.
• Limited cell numbers and inter-patient variability in biopsies pose challenges for TME analysis.
• Exhausted T cells (T_EX) are key dysfunctional immune cells in cancer progression.

Purpose of the Study:

• To develop a comprehensive spectral cytometry panel for deep phenotyping of T cells in the TME.
• To investigate the heterogeneity of CD8+ T_EX subsets and other immune cells like CD4 T, CD8 T, regulatory T (Treg), and γδ2 cells.
• To optimize staining protocols for dissociated tumor cells (DTCs), considering the impact of tissue dissociation enzymes.

Main Methods:

• Leveraged spectral cytometry for high-dimensional profiling with fewer cells compared to mass cytometry.
• Developed and utilized a customized 39-color panel for extensive T cell phenotyping.
• Evaluated the effects of tissue dissociation enzymes on staining protocols using cryopreserved peripheral blood mononuclear cells (PBMCs).
• Optimized intracellular marker staining for enhanced functional insights into T_EX cells.

Main Results:

• Demonstrated the feasibility of extensive immune profiling from limited tumor biopsies using spectral cytometry.
• Identified distinct profiles and heterogeneity within CD8+ T_EX subsets and other T cell populations.
• Assessed the impact of tissue dissociation enzymes, crucial for optimizing protocols for dissociated tumor cells (DTCs).

Conclusions:

• Spectral cytometry offers a powerful approach for in-depth TME analysis, maximizing data from scarce clinical samples.
• The developed panel and optimized protocol enhance the understanding of T_EX cell biology and function.
• This research facilitates the identification of novel therapeutic targets to improve antitumor immunity and patient outcomes.