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Buffy coat
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<h2 id="description">Description</h2><p> After centrifugation, one can distinguish a layer of clear fluid (the <a href="/facts/Blood_plasma/oHuwwugG">plasma</a>), a layer of red fluid containing <a href="/facts/Erythrocytes/Kggpq8Jh">erythrocytes</a>, and a thin layer in between. Composing less than 1% of the total volume of the blood sample, the buffy coat (so-called because it is usually <a href="/facts/Buff_(colour)/Sw3myk66">buff</a> in hue), contains most of the <a href="/facts/Leukocytes/vsDunUK0">leukocytes</a> and <a href="/facts/Thrombocytes/I0xrDVGa">thrombocytes</a>.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a><a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> The buffy coat is usually whitish in color, but is sometimes green if the blood sample contains large amounts of <a href="/facts/Neutrophil_granulocyte/KL6oTt8b">neutrophils</a>, which are high in green-colored <a href="/facts/Myeloperoxidase/UqYpgUrh">myeloperoxidase</a>.</p> <p>The buffy coat is commonly used for <a href="/facts/DNA/nB89Iauz">DNA</a> extraction,<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> with leukocytes providing approximately 10 times more concentrated sources of nucleated cells.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> Mammalian erythrocytes are <a href="/facts/Cell_nucleus/D7sFRa3c">anucleate</a> and do not contain DNA, so erethrocytes are normally removed for DNA analysis. A common protocol is to store buffy coat specimens for future DNA isolation and these may remain in frozen storage for many years.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> </p> <h2 id="diagnostic-uses">Diagnostic uses</h2> <p>Quantitative buffy coat (QBC), based on the centrifugal stratification of blood components, is a <a href="/facts/Medical_laboratory/ov10GjQD">laboratory</a> test for the detection of malarial parasites, as well as of other blood <a href="/facts/Parasite/HWPcgky7">parasites</a>.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> </p><p>The blood is taken in a QBC capillary tube which is coated with <a href="/facts/Acridine_orange/U4NqwxP8">acridine orange</a> (a fluorescent dye) and centrifuged; the <a href="/facts/Fluorescence/qsJVT2qP">fluorescing</a> parasitized erythrocytes get concentrated in a layer which can then be observed by <a href="/facts/Fluorescence_microscopy/eMwIdrRR">fluorescence microscopy</a>,<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> under <a href="/facts/Ultraviolet_radiation/kncBUqn5">ultraviolet radiation</a> at the interface between erythrocytes and buffy coat. This test is more sensitive than the conventional <a href="/facts/Thick_smear/ao2R0t11">thick smear</a> and in over 90% of cases the species of parasite can also be identified.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a><a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> </p><p>In cases of extremely low leukocyte count, it may be difficult to perform a manual differential of their various types and it may be virtually impossible to obtain an automated differential. In such cases, the <a href="/facts/Medical_technologist/hefPrVtN">medical technologist</a> may obtain a buffy coat, from which a blood smear is made. This smear contains a much higher number of leukocytes than whole blood.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> </p> <h2 id="medical-research">Medical Research</h2> <p>Since the buffy coat is mostly composed of leukocytes, it is a useful in human medical research, especially in cases where blood is the only experimental sample. Peripheral blood mononuclear cells (PBMCs) can be extracted from the buffy coat, and can be frozen for storage, or used to conduct immunological exepriments. </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Leukocytes/vsDunUK0">Leukocytes</a></li> <li><a href="/facts/Ficoll/E1nMM2zc">Ficoll</a></li> <li><a href="/facts/Malaria/rN3g58CX">Malaria</a></li></ul> <h2 id="external-links">External links</h2> <ul><li><a href="https://meshb.nlm.nih.gov/record/ui?name=Blood+Buffy+Coat">Blood Buffy Coat</a> at the U.S. National Library of Medicine <a href="/facts/Medical_Subject_Headings/C57g2JuF">Medical Subject Headings</a> (MeSH)</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Cottler-Fox, Michele; Montgomery, Matthew; Theus, John (2009-01-01), Treleaven, Jennifer; Barrett, A John (eds.), "CHAPTER 24 - Collection and processing of marrow and blood hematopoietic stem cells", Hematopoietic Stem Cell Transplantation in Clinical Practice, Edinburgh: Churchill Livingstone, pp. 249–256, ISBN 978-0-443-10147-2, retrieved 2022-08-09 <a href="978-0-443-10147-2" target="_blank">978-0-443-10147-2</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Mescher, Anthony L. (2018). "Blood". Junqueira's Basic Histology: Text and Atlas (15 ed.). McGraw-Hill Education. p. 237. ISBN 9781260026184. <a href="9781260026184" target="_blank">9781260026184</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Marieb, Elaine N. (2007). Human Anatomy & Physiology (Seventh ed.). San Francisco: Pearson Benjamin Cummings. ISBN 978-0-8053-5910-7. <a href="978-0-8053-5910-7" target="_blank">978-0-8053-5910-7</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Mychaleckyj, Josyf C; Farber, Emily A; Chmielewski, Jessica; Artale, Jamie; Light, Laney S; Bowden, Donald W; Hou, Xuanlin; Marcovina, Santica M (10 June 2011). "Buffy coat specimens remain viable as a DNA source for highly multiplexed genome-wide genetic tests after long term storage". Journal of Translational Medicine. 9: 91. doi:10.1186/1479-5876-9-91. ISSN 1479-5876. PMC 3128059. PMID 21663644. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3128059" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3128059</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Fabre, Anne-Lise; Luis, Aurélie; Colotte, Marthe; Tuffet, Sophie; Bonnet, Jacques (30 November 2017). "High DNA stability in white blood cells and buffy coat lysates stored at ambient temperature under anoxic and anhydrous atmosphere". PLOS ONE. 12 (11): e0188547. Bibcode:2017PLoSO..1288547F. doi:10.1371/journal.pone.0188547. PMC 5708797. PMID 29190767. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5708797" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5708797</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Gustafson, Sarah; Proper, Jacqueline A.; Bowie, E. J. Walter; Sommer, Steve S. (1 September 1987). "Parameters affecting the yield of DNA from human blood". Analytical Biochemistry. 165 (2): 294–299. doi:10.1016/0003-2697(87)90272-7. ISSN 0003-2697. PMID 3425899. <a href="https://www.sciencedirect.com/science/article/abs/pii/0003269787902727" target="_blank">https://www.sciencedirect.com/science/article/abs/pii/0003269787902727</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Ahmed, Nishat Hussain; Samantaray, Jyotish Chandra (2014). "Quantitative Buffy Coat Analysis-An Effective Tool for Diagnosing Blood Parasites". Journal of Clinical and Diagnostic Research. 8 (4): DH01. doi:10.7860/JCDR/2014/7559.4258. ISSN 2249-782X. PMC 4064892. PMID 24959448. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4064892" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4064892</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Ahmed, Nishat Hussain; Samantaray, Jyotish Chandra (2014). "Quantitative Buffy Coat Analysis-An Effective Tool for Diagnosing Blood Parasites". Journal of Clinical and Diagnostic Research. 8 (4): DH01. doi:10.7860/JCDR/2014/7559.4258. ISSN 2249-782X. PMC 4064892. PMID 24959448. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4064892" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4064892</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Sherman, Angel (2018). Medical Parasitology. EDTECH. ISBN 9781839473531. <a href="9781839473531" target="_blank">9781839473531</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Kochareka, Manali; Sarkar, Sougat; Dasgupta, Debjani; Aigal, Umesh (October 2012). "A preliminary comparative report of quantitative buffy coat and modified quantitative buffy coat with peripheral blood smear in malaria diagnosis". Pathogens and Global Health. 106 (6): 335–339. doi:10.1179/2047773212Y.0000000024. PMC 4005131. PMID 23182137. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4005131" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4005131</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Blumenreich, Martin S. (1990). The White Blood Cell and Differential Count (3rd ed.). Butterworths. ISBN 978-0-409-90077-4. PMID 21250104. <a href="978-0-409-90077-4" target="_blank">978-0-409-90077-4</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> </ol>