Benefits of using Flow Cytometry in Detecting and Monitoring Tumor Infiltrating Lymphocytes

The microenvironments of solid tumors are composed of cancer cells, stromal cells and immune cells. Each of these cell types influences others to execute processes such as cancer progression, tumor invasion and immune evasion. Tumor infiltrating lymphocytes ( TIL’s) found in the tumor microenvironment form a complex network, with specialized functions to recognize and eliminate tumor cells or foreign bodies. For example, effector cells directly eliminate foreign pathogens and cancer cells. Non-effector cells indirectly influence cancer cell death through modulating the cytotoxic effector T cell response.  Recognition between normal, and pathogen or abnormal cells is regulated by a balance between co-stimulatory and inhibitory signals. These signals may be secreted directly by the tumor cells to provide host immunity and promote resistance to therapeutic intervention.

Since cell-based therapy focuses on various immune cell types and their behavior in cancer, flow cytometry represents a powerful and versatile technology for the interrogation of immune cell responses and their effects on cancer cells. An example of such a flow assay is the quantification and characterization of specific subsets of circulating tumor-specific T cells that are derived from the tumor and then selected against known Tumor Specific Antigens (TSA) generated from the tumor itself. These purified tumor-specific T cells are then expanded and reinfused into the patient along with an immune booster like IL-2.  This type of analysis provides a platform to better gauge the immunogenicity of the therapy and the ability of the immune cells to successfully identify and attack cancer cells.

The use of flow cytometry is at the forefront of this medical revolution, as an empowering and versatile technology enabling in-depth analysis of tumor infiltrating lymphocytes and their potential role in cancer biology and effective therapeutic intervention.