The BD FACSVia™ flow cytometer is equipped with a blue laser, a red laser, two light scatter detectors, and four fluorescence detectors. A compact optical design, fixed alignment, pre-optimized detector settings, and automated adjustment of fluorescence spillover. The BD FACSVia™ clinical software contains assay-specific templates providing clinical menus that include: 1.) counting residual white blood cells (rWBCs) in leucoreduced blood products; 2.) in vitro diagnostic use to identify and enumerate residual white blood cells (rWBCs), red blood cells (rRBCs), and platelets (rPLTs) in fresh human plasma; 3.) immunophenotyping human peripheral whole blood and 4.) rapid detection of HLA-B27 antigen expression in erythrocyte-lysed whole blood (LWB).