Evaluation of Suspected Immunodeficiency, Flow Cytometry

Flow cytometry is a laboratory tool that has become standard in the evaluation of hematopoietic cell subpopulations. The application of flow cytometry allows for the detailed assessment of cell surface markers, intracellular protein expression, cellular activation, and cell death that characterize all immunodeficiencies. A flow cytometer analyzes the physical and chemical characteristics of cells in a fluid status that pass through a laser in single file. Cells are labeled with florescent markers that emit light at varying wavelengths.

The components of a flow cytometer are the light source, optical bench, fluidic system, and computer. Stained cells enter in single file through the fluidic system, are interrogated by the light source, then generated light signals are directed by the optical system to the photodetectors, and light is converted into an electronic signal. Analysis programs often evaluate the number and percentage of events, detect the mean or median channel florescence,...