51 4.4: Flow Cytometry

Flow cytometry is another experimental procedure that can be used to analyze physical and chemical characteristics of a group of cells or particles. Flow cytometry is a very useful tool that is used in various fields of application such as immunology, virology, molecular biology, and especially in the context of this unit, cancer biology. There have been many upgrades to the flow cytometry technology over the past couple decades and it has become an essential tool in research.

How It Works

The flow cytometer machines use laser light sources to produce light signals which are then detected and analyzed by a computer. The scatter of visible light is measured by the forward direction (Forward scatter – FSC), which indicates cell size, and the sideways 90° direction (Sideways Scatter – SSC), which indicates the granularity of the cell. The following video explains the experimental technique of flow cytometry.

Flow Cytometry and LIF

Although flow cytometry has been shown to have many applications, the focus for this chapter will be how it can be used in investigating cancer biology. Referring back to the Pascual-García, et al. study, the researchers conducted another experiment this time using an in vivo model. They wanted to further explore the effect of the LIF blockade and its dependency on CXCL9. To study this, the authors inoculated tumours from patients with high LIF expression into NSG mice which were then treated with LIF neutralizing antibodies. The mice were then inoculated with the patients’ peripheral blood mononuclear cells in order to analyze the infiltration of T cells into the tumor. The CD8+ T cells in the tissue and blood were detected using flow cytometry. The results indicated that mice treated with anti-LIF had increased tumour infiltration and the CD8+ T cells displayed receptors for the CXCL9 cytokine (Fig.1).

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