Cell Staining Buffer is an antibody diluent and cell wash buffer optimized for use in immunofluorescent staining of viable or fixed single cell suspensions. Cell Staining Buffer contains fetal bovine serum as a protein carrier to reduce non-specific binding of antibodies and fluorochrome reagents to target cells. It also contains a metabolic inhibitor, sodium azide (NaN₃), to inhibit patching and capping of cell surface antigens. To prevent interference in biotin/avidin indirect staining protocols, Cell Staining Buffer is formulated without biotin.