Flow cytometry and immunohistochemistry are laboratory techniques used in the detection of antigens on the cell surface or within cells. 

• Flow Cytometry: Flow cytometry is a laser-based technique. It uses a flow cytometer and a laser beam for detecting and quantifying the physical and chemical characteristics of a population of cells or particles. Laser as a light source is a mandatory requirement for this technique. The analysis is performed using a computer. 
• Immunohistochemistry: Immunohistochemistry is a microscopy-based technique. It uses a light or fluorescent microscope and monoclonal or polyclonal antibodies for the selective identification and localization of antigens in cells of a tissue. Monoclonal or polyclonal antibodies are a mandatory requirement for this technique. Analysis is performed by viewing the results under a light or fluorescent microscope.