anti-CD8a Molecule (CD8A) antibody (PE): The reagent CD8 PE permits identification and enumeration of cell populations expressing human CD8 antigen in whole blood using flow cytometry. This test is based on specific binding of monoclonal antibody to the antigenic determinant expressed on the surface of leukocytes. The monoclonal antibody is labeled with fluorochrome which is excited via laser beam from a flow cytometer during analysis. Subsequent emission of light from fluorochromes of each cell is collected and analyzed by a flow cytometer. The fluorescence intensity differences enable separation of cell subsets based on expression of analyzed antigen.