Plasma contains a large variety of
proteins including albumin, immunoglobulin, and clotting proteins
such as fibrinogen in it. These proteins present in it
have many important therapeutic uses and clinical uses and can work wonders
when used in development of various medicines. These substances are also widely
used in medical researches to develop therapies and vaccines for chronic
diseases like cancer, tumors and AIDS etc.
In
order to get the benefit of these live saving substances plasma is extracted
from the human blood through a process called blood fractionation. Human Plasma is the
yellowish liquid present in the human blood that constitutes 55% of its volume
and is responsible for all the major circulation of it throughout the human
body. When this extraction is carried out we get a clear solution of
plasma in the upper phase, the Buffy coat, which is a thin layer
of leukocytes mixed with platelets in the middle and Erythrocytes (Red Blood Cells)
at the bottom of the centrifuge tube. After getting these components separately
in the tube, plasma can be separated easily and stored for further use.
Now
once the Human Plasma is obtained, its various components can be separated for
further usage. However it is also very beneficial and can be used in various
forms to create medications wholly. The process of separating the
various components of Human Blood Plasma is called
as Blood plasma fractionation.
The Human Blood Plasma contains thousands of proteins, however, identifying them
presents challenge due to the wide range of concentrations present in it. Let us
see different components and their concentration in it.
·
Albumin constitutes about
60% of the total protein in plasma and is present at concentrations between 35
and 55 mg/mL. It is the main
contributor to osmotic pressure of the blood and it functions as a
carrier molecule for molecules with low water solubility
such as lipid soluble hormones, enzymes, fatty acids, metal ions, and
pharmaceutical compounds. Due to the structural integrity of albumin it remains
stable under conditions where most other proteins denature.
·
Fibrinogen is present
at concentrations 1.5-4.0 g/L in Human Blood Plasma or about 7 µM. It is the principal
protein responsible for clotting in the human body.
·
Immunoglobulins are the
substances that fight against infections in human body. Our bodies create
antibodies (Immunoglobulin’s) against disease causing agents when infections
occur.
Apart from these there are many
other proteins and substances present in the human plasma in minute quantities that also can be separated
through the process of Blood plasma fractionation.
The first practical large scale method
of blood plasma fractionation was developed by Edwin J. Cohn during World War II. This process is also
known as cold ethanol fractionation as it involves gradually increasing the concentration of ethanol in the solution at 5oC and 3oC.
The Cohn Process exploits differences in properties of the various proteins,
specifically, the high solubility and low pl of albumin. However, at each stage
certain proteins are precipitated
out of the solution and removed.
The final precipitate is purified albumin.
Several variations to this process also
exist, including an adapted method by Nitschmann and Kistler that uses fewer
steps, and replaces centrifugation and bulk freezing with filtration and diafiltration. However, the
ultimate goal of processing is to get a purified component that can be used for making injection or transfusions.
In addition to the clinical uses of a variety of its proteins, it has many
analytical uses too. Blood plasma fractionation obtains it
in purified state that can be utilized for many purposes and have many
beneficial factors in it.