A buffy coat is a concentration of white blood cells (WBCs) and platelets. WBCs and platelets make up only around 1% of the cells in the volume of peripheral whole blood. When a blood sample is centrifuged, the platelets and WBCs unite to form a layer floating between the RBCs and supernatant plasma. Because of its hue, this thin coating is termed a buffy coat.
In this article, we’ll explore the various cell types in buffy coats, how buffy coats are extracted from whole blood, and the importance of this material for research.
Four Cell Types Exist in Buffy Coats
- Granulocytes – are immune cells that include basophils, eosinophils, and neutrophils.
- Platelets – are known as thrombocytes and have different functions in blood homeostasis.
- Lymphocytes – play an important function in the immune system. They include T cells, B cells, and natural killer cells.
- Monocytes – a type of leukocyte that aids in the immune response by identifying and digesting microbes. Monocytes can differentiate into dendritic cells or macrophages.
The cells contained in a buffy coat play a significant role in human disease pathogenesis. Studying the cells in the buffy coat benefits research and provides valuable scientific information.
Preparation of Buffy Coat
Anti-coagulated peripheral whole blood (e.g., Heparin, EDTA) is transferred to a pyrogen-free tube for centrifugation. The centrifugation separates the sample into three layers: the bottom or hematocrit layer consisting of red blood cells, an intermediate thin buffy coat layer, and a top plasma layer. Using a pipette, the buffy coat can be collected slowly.
The buffy coat may also be extracted from bone marrow samples. Different kits and protocols exist to optimize the preparation process.
Is the Buffy Coat the Same as PBMCs?
The terms buffy coat and peripheral blood mononuclear cells (PBMCs) are often used interchangeably. However, they are not the same, and they serve different purposes in research.
PBMCs contain lymphocytes and monocytes which remain a subset of all immune cells and do not include other cell types such as eosinophils, basophils, and neutrophils that are found in the buffy coat.[1] PBMCs are isolated from whole blood using one of several density centrifugation techniques. Upon centrifugation and according to the reagent protocols, the relatively lower density PBMCs migrate into a layer that floats on top of the reagent layer, where they can easily be extracted.
How Are Buffy Coats Used for Research?
- Buffy coats are rich in WBCs and platelets and therefore offers the potential to examine immunological pathways and molecular signals.
- Buffy coats are commonly used for DNA extraction purposes from mammalian blood. A relatively small sample of buffy coat can yield a large amount of DNA of high quality, integrity, and functionality.[2] Evidence has shown cell pellets derived from buffy coats can be stored for up to 9 years at a -80 °C and still maintain high yields of DNA suitable for whole-genome sequencing, genome-wide association analysis, and other genetic testing.[3]
- Circulating tumor cells (CTCs) may be found in the buffy coat of patients with malignancies and may help downstream analysis of potentially crucial molecular mechanisms of tumor resistance and metastasis.[4]
- Blood banks frequently separate whole blood samples to extract the buffy coat and cryopreserve platelets for further uses.
- The buffy coat has a practical utility in diagnostics. It can be utilized to diagnose the presence of parasitic infections such as plasmodium, microfilariae, and trypanosoma because important immune cells congregate in this layer.[5][6]
Buffy coats are a critical starting material for immunology research and other downstream applications. These products are rich in immune cells and platelets and are commonly requested by Cytologics customers.
Are you interested in learning more about buffy coats or have a specific biospecimen request? Then reach out to our scientific team to discuss how we can support your research!
