PLASMAPHERESIS

PLASMAPHERESIS

Plasmapheresis is an experimental procedure done in animals to demonstrate the importance of plasma proteins. Earlier, this was called Whipple’s experiment because it was established by George Hoyt Whipple.

PROCEDURE

Plasmapheresis is demonstrated in dogs. Blood is removed completely from the body of the dog. Red blood cells are separated from plasma and are washed in saline and reinfused into the body of the same dog along with a physiological solution called Locke’s solution. Due to sudden lack of proteins, the animal undergoes a state of shock. If the animal is fed with diet containing sufficiently high quantity of proteins, the normal level of plasma proteins is restored within seven days and the animal survives. The new plasma proteins are synthesized by the liver of the dog. If the experiment is done in animals after removal

of liver, even if the diet contains adequate quantity of proteins, the plasma proteins are not produced. The

shock persists in the animal and leads to death. Thus, the experiment ‘plasmapheresis’ is used to

demonstrate:

1. Importance of plasma proteins for survival

2. Synthesis of plasma proteins by the liver.

CLINICAL SIGNIFICANCE OF PLASMAPHERESIS – THERAPEUTIC PLASMA EXCHANGE

Plasmapheresis is used as a blood purification procedure for an effective temporary treatment of many autobecause immune diseases. It is also called therapeutic plasma exchange. In an autoimmune disease, the immune system attacks the body’s own tissues through antibodies. The antibodies that are proteins in nature circulate in the bloodstream before attacking the target tissues. Plasmapheresis is used to remove these antibodies from the blood.

Procedure

Venous blood is removed from the patient and blood cells are separated from plasma by the equipment called cell separator. This equipment works on the principle of a centrifuge. An anticoagulant is used to prevent the clotting of blood when it is removed from the body. After the separation of blood cells, the plasma is discarded. The blood cells are returned to the bloodstream of the patient by mixing with a substitute fluid (saline) and sterilized human albumin protein.

Uses of Plasmapheresis

Though plasmapheresis is used to remove antibodies from the blood, it cannot prevent the production of

antibodies by the immune system of the body. So, it can provide only a temporary benefit of protecting the tissues from the antibodies. The patients must go for repeated sessions of this treatment.

Plasmapheresis is an effective temporary treatment

for the following diseases:

1. Myasthenia gravis – autoimmune disease causing muscle weakness (Chapter 17)

2. Thrombocytopenic purpura – bleeding disorder 3. Paraproteinemic peripheral neuropathy – dysfunction

of peripheral nervous system due to an abnormal immunoglobulin called paraprotein.

4. Chronic demyelinating polyneuropathy – neurological disorder characterized by progressive weakness

and impaired sensory function in the legs and arms due to the damage of myelin sheath in

peripheral nerves.

5. GuillainBarré syndrome – autoimmune disease causing weakness, abnormal sensations (like

tingling) in the limbs and paralysis.

6. LambertEaton myasthenic syndrome – autoimmune disorder of the neuromuscular junction.

VARIATIONS IN PLASMA PROTEIN LEVEL

Level of plasma proteins vary independently of one another. However, in several conditions, the quantity

of albumin and globulin change in opposite direction. Elevation of all fractions of plasma proteins is called

hyperproteinemia and decrease in all fractions of plasma proteins is called hypoproteinemia.