Plasma

Plasma is the largest single component of blood, and makes up about 55% of total blood volume. It is a clear, straw-coloured liquid, which carries platelets, red and white blood cells.

It contains over 700 proteins and other substances, which can be extracted and which are key ingredients in medical products.

Once separated from blood cells, plasma can be:

• used in blood transfusions
• separated out into its many individual proteins which are used to make medical products

Plasma products and their uses

These products can be grouped into three main types:

• clotting or coagulation factors
• albumin solutions
• immunoglobulins

Coagulation or clotting factors

Coagulation is the name for the complex process of blood clotting. Clotting factors are proteins that work together with platelets to clot blood.

People need clotting factors for their blood to successfully clot. Missing one or more of these factors leads to blood clotting disorders such as haemophilia and Von Willebrand disease.

In the UK, haemophilia is commonly treated with 'recombinant factors' that are manufactured in a laboratory and do not come from donated plasma.

Other blood clotting disorders that are treated with coagulation factors made from donated plasma.

Albumin

Albumin is the most common protein in blood plasma. It helps to:

• carry substances around the body
• maintain the right amount of fluid circulating in the body

If the circulation is working properly, vital hormones, cells and enzymes are transported to the right parts of the body to do their job.

If it's not working properly, the circulatory system starts to break down, with serious consequences such as fluids being retained in the cells.

This can be treated by using human albumin solution which makes sure that the right amount of fluid is circulating in the blood stream.

Albumin can also be used to treat people with some types of liver or kidney disease and patients who have suffered burns.

Immunoglobulins

Immunoglobulins are protective antibodies which are produced by the body to fight against invading viruses or bacteria. There are two different types of immunoglobulins, specific and non-specific.

Specific immunoglobulins

Specific immunoglobulins contain high levels of antibody to a particular illness. These are given to people who have been exposed to a specific infection.

Antidotes to tetanus, rabies, chickenpox and hepatitis are all examples of specific immunoglobulins.

For example, a donor who has had chicken pox will have high levels of chicken pox antibodies. So their plasma would be ideal to treat a child with leukaemia who has been exposed to chicken pox.

Non-specific immunoglobulins

Non-specific immunoglobulins contain a wide variety of antibodies. These are given to people:

• who make faulty antibodies, or can’t make their own antibodies
• who are having treatments for diseases like cancer, where the treatment harms their ability to make antibodies

People with a faulty immune system need these products to live. Over 1,000 donations of plasma contribute to a single dose of an immunoglobulin product that contains all the necessary antibodies.

Separating plasma products

Plasma is first tested to be sure it's safe to use, in the same way that whole blood is tested.

Many chemical and physical processes (eg spinning and heat treatments) are then carried out to separate the individual proteins. This is known as the fractionation process.

This process is fully automated and takes up to five days to complete.

Solvent or detergent treatment, dry heat treatment, filtration and pasteurisation are also used to kill or remove any viruses that may be present.

The finished products are then tested again to make sure they contain the right biological make-up.

Once processing and testing is complete, the products are labeled, coded and packed, ready to be used by hospitals, clinics and doctors’ surgeries.

The total number of products that can be made with plasma fractionation runs into hundreds.