Blood Groups and Transfusions

What is an antigen?

An antigen is a marker that indicates to the immune system whether something in your body is harmful or not.

It is capable of causing the formation of antibodies when introduced into the tissue.

What is antibody

A substance produced in response to a specific antigen; it combines with the antigen to neutralise and destroy it.

What is agglutination

The clumping together of micro-organisms or of blood cells

What is the ABO blood group system?

A method of classifying blood types according to the antigens on the surface of the red blood cells

What are the types of blood groups in the ABO system?

• Type A

• Type B

• Type AB

• Type O

What are the types of antigens for each blood group?

• Type A (Antigen A)

• Type B (Antigen B)

• Type AB (Antigen A and Antigen B)

• Type O (neither Antigen A nor Antigen B)

What are the types of antibodies produced for each blood group?

• Type A (Antibody B)

• Type B (Antibody A)

• Type AB (neither Antibody A nor Antibody B)

• Type O (Antibody A and Antibody B)

What is the rhesus blood group system?

It is based on the Rh antigens, which are proteins, that occur on the surface of the red blood cells

• A person with Rh antigens is said to be Rh positive

• A person without Rh antigens is said to be Rh negative

  An individual without the Rh antigens is able to produce an anti-Rh antibody that reacts against those antigens. Rh-positive individuals cannot produce an anti-Rh antibody.

What are the types of rhesus blood groups?

• Type A+ (Antigen A, Rhesus Antigen)

• Type A - (Antigen A, No Rhesus Antigen)

• Type B+ (Antigen B, Rhesus Antigen)

• Type B- (Antigen B, No Rhesus Antigen)

• Type AB+ (Antigen A, Antigen B, Rhesus Antigen)

• Type AB- (Antigen A, Antigen B, No Rhesus Antigen)

• Type O+ (No Antigen A, No Antigen B, Rhesus Antigen)

• Type O- No Antigen A, No Antigen B, No Rhesus Antigen)

What blood types can donate to others?

• Type A - donates to A, and AB

• Type B - donates to B, and AB

• Type AB - donates to AB

• Type O - donates to O, A, B, and AB (Universal Donor)

What blood types can receive from others?

• Type A - receives from A, O

• Type B - receives from B and O

• Type AB - receives from A, B, AB, and O (Universal Acceptor)

• Type O - receives from O

What are the types of blood transfusions?

• Whole blood

• Red cell concentrates

• Platelet concentrates

• Cryoprecipitate

• Immunoglobulins

• Autologous Transfusion

Whole Blood

Whole blood is blood as it is taken from the donor but with a chemical added to prevent clotting. These kinds of transfusions are usually rare but can often occur in cases of severe blood loss.

Red Cell Concentrates

This is the most widely used component of blood. They are produced by spinning blood at a very high speed in a centrifuge. The heavier cells sink to the bottom, leaving the lighter plasma on the top. The concentrate may or may not have platelets and white blood cells removed. Red cell concentrates are used mostly for patients suffering from heart disease or severe anaemia.

Plasma, the liquid part of the blood, may be given to patients requiring extra clotting factors for control of severe bleeding, or to patients with liver disease.

Platelet Concentrates

Given to patients who have abnormal platelets or a reduced number of platelets.

Cryoprecipitate

Cryoprecipitate is obtained by freezing plasma and thawing it slowly. When the plasma is thawed, the cryoprecipitate remains solid. It contains many of the substances needed for blood clotting. Cryoprecipitate may be used to treat some forms of haemophilia, but is most often used for severe bleeding.

Immunoglobins

Immunoglobulins are a group of proteins that act as antibodies. They are extracted from the blood and used for patients who are deficient in antibodies. Particular immunoglobulins from certain donors are used to treat patients who have no immunity to a particular disease. For example, tetanus immunoglobulin may be used to treat tetanus.

Autologous Transfusion

An autologous transfusion is when the patient’s own blood is used. The blood is collected from the patient prior to an operation that may require a transfusion. Such transfusions are often used for elective surgery and the blood is collected about four weeks before the operation. Autologous transfusions eliminate the risk of transmission of disease and most possible side effects of the usual transfusions.