Blood fractionation is the process of
fractionating whole blood
Whole blood (WB) is human blood from a standard blood donation. It is used in the treatment of massive bleeding, in exchange transfusion, and when people donate blood to themselves (autologous transfusion). One unit of whole blood (approxima ...
, or separating it into its component parts. This is typically done by
centrifuging the
blood
Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells.
Blood is com ...
.
The resulting components are:
* a clear
solution
Solution may refer to:
* Solution (chemistry), a mixture where one substance is dissolved in another
* Solution (equation), in mathematics
** Numerical solution, in numerical analysis, approximate solutions within specified error bounds
* Solu ...
of
blood plasma
Blood plasma is a light Amber (color), amber-colored liquid component of blood in which blood cells are absent, but which contains Blood protein, proteins and other constituents of whole blood in Suspension (chemistry), suspension. It makes up ...
in the upper phase (which can be separated into its own fractions, see
Blood plasma fractionation),
* the
buffy coat, which is a thin layer of
leukocyte
White blood cells (scientific name leukocytes), also called immune cells or immunocytes, are cells of the immune system that are involved in protecting the body against both infectious disease and foreign entities. White blood cells are genera ...
s (white blood cells) mixed with
platelet
Platelets or thrombocytes () are a part of blood whose function (along with the coagulation#Coagulation factors, coagulation factors) is to react to bleeding from blood vessel injury by clumping to form a thrombus, blood clot. Platelets have no ...
s in the middle, and
*
erythrocyte
Red blood cells (RBCs), referred to as erythrocytes (, with -''cyte'' translated as 'cell' in modern usage) in academia and medical publishing, also known as red cells, erythroid cells, and rarely haematids, are the most common type of blood ce ...
s (red blood cells) at the bottom of the centrifuge tube.
Serum separation tubes (SSTs) are tubes used in
phlebotomy
Phlebotomy is the process of making a puncture in a vein, usually in the arm, with a cannula for the purpose of drawing blood. The procedure itself is known as a venipuncture, which is also used for intravenous therapy. A person who performs a ...
containing a silicone gel; when centrifuged the silicone gel forms a layer on top of the buffy coat, allowing the blood serum to be removed more effectively for testing and related purposes.
As an alternative to energy-consuming centrifugation, more energy-efficient technologies have been studied, such as ultrasonic fractionation.
Plasma protein fractionation
Plasma proteins are separated by using the inherent differences of each protein. Fractionation involves changing the conditions of the pooled plasma (e.g., the temperature or the acidity) so that proteins that are normally dissolved in the plasma fluid become insoluble, forming large clumps, called precipitate. The insoluble protein can be collected by
centrifugation
Centrifugation is a mechanical process which involves the use of the centrifugal force to separate particles from a solution according to their size, shape, density, medium viscosity and rotor speed. The denser components of the mixture migrate ...
. One of the very effective ways for carrying out this process is the addition of alcohol to the plasma membrane pool while simultaneously cooling the pool. This process is sometimes called cold alcohol fractionation or
ethanol
Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...
fractionation. It was described by and bears the eponym of Dr
Edwin J. Cohn. This procedure is carried out in a series of steps so that a single pool of plasma yields several different protein products, such as albumin and immune globulin.
Statement by Dr. Kathryn Zoon, Food and Drug Administration
(before the U.S. Congress, July 31, 1997) (via archive.org) Human serum albumin prepared by this process is used in some vaccines, for treating burn victims, and other medical applications.
See also
* Blood plasma fractionation
References
{{Reflist
Blood
Fractionation
Medical technology