Flow cytometry is a powerful analytical tool used in oncology to measure and analyze multiple phenotypic characteristics of cells as they flow in a fluid stream through a laser. It is widely used in oncology for diagnosing and classifying cancers, particularly hematological malignancies like leukemia and lymphoma. Flow cytometry helps identify specific cell populations based on surface markers, assess cell proliferation, determine apoptosis and cell death, and detect minimal residual disease (MRD). It is also instrumental in evaluating the immune profile of tumors and monitoring disease progression or response to therapy.

Flow cytometry services can greatly enhance in vivo models by providing detailed, quantitative analysis of cell populations within tissues or blood samples. These services enable the assessment of immune cell infiltration in tumors, characterization of circulating tumor cells, and monitoring of immune responses in preclinical models. By analyzing cells from in vivo models, flow cytometry can offer insights into the efficacy of therapeutic interventions, such as the activation or suppression of specific immune cell types, thus aiding in the development of cancer therapies.

The typical workflow for a flow cytometry experiment involves several key steps:

1. Sample Preparation: Cells are harvested, counted, and often labeled with fluorescently conjugated antibodies that target specific markers.
2. Fixing: Cells are fixed with formaldehyde in order to preserve the structure of the cells as well as keep markers intact throughout the experiment.
3. Permeabilization: It is required to permeabilize cells prior to staining for the detection of intracellular cytokines.
4. Blocking: Depending on the experiment and marker specificity, it is important to block for Fc receptors to prevent additional background stain uptake to the cells. If you are determining intracellular cytokine production for a particular cellular subset, it is important to block the secretion of cytokines with Brefeldin A and/or Monensin, which results in the increased accumulation of cytokines in the cell.
5. Staining: The prepared cells are incubated with the chosen antibodies or dyes. Specific negative and positive controls must be created to ensure experimental analysis is completed correctly.
6. Data Acquisition: The stained cells are passed through the flow cytometer, where lasers excite the fluorophores, and detectors measure the emitted light, quantifying various cell properties.
7. Data Analysis: The collected data are processed using specialized software to interpret the results, such as identifying cell populations, analyzing marker expression, or assessing cell viability.

Flow cytometry plays a crucial role in monitoring treatment response in cancer by allowing for the detailed analysis of how cancer cells and the immune system respond to therapy. It can detect changes in cell populations, such as the reduction of cancer cells or the activation of immune cells, in response to treatments like chemotherapy, immunotherapy, or targeted therapies. Flow cytometry also enables the detection of minimal residual disease (MRD), helping to assess whether a treatment is effectively eliminating cancer cells or if there is a need for alternative therapeutic strategies.

Flow cytometry is extensively used in immuno-oncology research to analyze the immune landscape within tumors and the systemic immune response to cancer. It allows researchers to identify and quantify different immune cell populations, within the tumor microenvironment or peripheral blood. Flow cytometry is also used to assess the expression of immune checkpoint molecules, cytokines, and other markers that indicate immune activation or suppression. This information is critical for understanding how tumors evade the immune system, mechanisms of resistance, and for developing and optimizing immunotherapies.