CD107a Degranulation Assay to Evaluate Immune Cell Antitumor Activity

Cancer development is under surveillance by the immune system of the host. Tumor cells can be recognized and killed by cytotoxic lymphocytes— such as CD8+ T lymphocytes and natural killer (NK) cells—mainly through the immune secretion of lytic granules that kill target cells. This process involves the fusion of the granule membrane with the cytoplasmic membrane of the immune effector cell, resulting in surface exposure of lysosomal-associated proteins that are typically present on the lipid bilayer surrounding lytic granules, such as CD107a. Therefore, membrane expression of CD107a constitutes a marker of immune cell activation and cytotoxic degranulation. In this chapter, we detail the steps required to isolate peripheral blood mononuclear cells (PBMCs), coculture them with target tumor cell lines, and evaluate the cytotoxic immune function by means of flow cytometry evaluation of CD107a expression on the surface of NK cells.