The liquid component of blood is called plasma, and it is separated by spinning or centrifuging the blood at high rotations (3000 rpm or higher). The blood cells and platelets are separated by centrifugal forces to the bottom of a specimen tube. The upper liquid layer, the plasma, consists of 90 percent water along with various substances required for maintaining the body’s pH, osmotic load, and for protecting the body. The plasma also contains the coagulation factors and antibodies.
The plasma component of blood without the coagulation factors is called the serum. Serum is similar to interstitial fluid in which the correct composition of key ions acting as electrolytes is essential for normal functioning of muscles and nerves. Other components in the serum include proteins that assist with maintaining pH and osmotic balance while giving viscosity to the blood. The serum also contains antibodies, specialized proteins that are important for defense against viruses and bacteria.
The three most important plasma proteins from a market perspective include albumin, immunoglobulins (IgGs) and plasma-derived factor VIII. In 2017, immunoglobulin captured the leading position with more than 45% market share. Other plasma proteins of note include ?1-antitrypsin (AAT), hyperimmune immunoglobulins, coagulation factors, fibrogammin and c1 esterase inhibitors (C1 INH).
Plasma proteins have traditionally been isolated from plasma using cold ethanol fractionation. Acid, alcohol and salts are employed at cold temperatures to precipitate proteins into fractions containing many proteins in their non-native forms. Specific proteins are purified by re-solubilizing the precipitated fractions. The method was initially developed in the 1940s by Harvard University professor Edwin Cohn to provide albumin for treatment of soldiers injured during World War II.
Blood are a mixture of simple proteins, glycoproteins, lipoproteins, and other conjugated proteins are called “Plasma Proteins “. Salt precipitation, immunological technique, and electrophoresis may separate these.
The three major fractions of plasma proteins are known as Albumin, globulin, and Fibrinogen. On a finer resolution by electrophoresis, these fractions are separated as follows –