A buffy coat is a fraction of an anticoagulated blood sample that contains most of the white blood cells and platelets following centrifugation. After centrifugation, the buffy coat is the layer of white blood cells present in between the erythrocytes and the clear plasma obtained. Buffy coats are commonly used for DNA extraction, with white blood cells providing approximately 10 times more concentrated sources of nucleated cells. They are extracted from the blood of mammals because mammalian red blood cells are anucleate and do not contain DNA. Buffy coats consist mainly of four types of cells: lymphocytes, monocytes, granulocytes, and platelets. The cells that can be found in a buffy coat are essential to protecting humans from disease and healing from wounds. The buffy coat can be useful for researchers doing work with toxicology or for patients with dysfunctional white blood cells or platelets. Beyond its implications in research, the buffy coat also has a practical application in testing for certain diseases and treating patients. Because key immune cells concentrate in this layer, the buffy coat can be used diagnostically when looking for the presence of harmful diseases such as malaria. The platelets can also be further purified and used therapeutically to increase counts in patients who may have low platelet levels. Veterinary clinics also use buffy coat examination to look for abnormal white blood cells that are circulating in the blood, such as mast cells.