Blood fractionation is the process of
fractionating whole blood, 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 in th ...
.
The resulting components are:
* a clear
solution of
blood plasma
Blood plasma is a light amber-colored liquid component of blood in which blood cells are absent, but contains proteins and other constituents of whole blood in suspension. It makes up about 55% of the body's total blood volume. It is the ...
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, also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from mul ...
s (white blood cells) mixed with
platelets in the middle, and
*
erythrocytes (red blood cells) at the bottom of the centrifuge tube.
Serum separation tubes (SSTs) are tubes used in
phlebotomy 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. 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 (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a h ...
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
The Internet Archive is an American digital library with the stated mission of "universal access to all knowledge". It provides free public access to collections of digitized materials, including websites, software applications/games, music ...
) 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