There are 4 main blood groups (types of blood) which are: A, B, AB and O. Your blood group is determined by the genes you inherit from your parents.

Each group can be either RhD positive or RhD negative, which means in total there are 8 blood groups.

Antibodies and antigens
Blood is made up of red blood cells, white blood cells and platelets in a liquid called plasma. Your blood group is identified by antibodies and antigens in the blood.

Antibodies are proteins found in plasma. They’re part of your body’s natural defences. They recognise foreign substances, such as germs, and alert your immune system, which destroys them.

Antigens are protein molecules found on the surface of red blood cells.

The ABO system
There are 4 main blood groups defined by the ABO system:

1. Blood group A – has A antigens on the red blood cells with anti-B antibodies in the plasma.

2. Blood group B – has B antigens with anti-A antibodies in the plasma

3. Blood group O – has no antigens, but both anti-A and anti-B antibodies in the plasma

4. Blood group AB – has both A and B antigens, but no antibodies.

Blood group O is the most common blood group. Almost half of the UK population (48%) has blood group O. Receiving blood from the wrong ABO group can be life threatening.

if someone with group B blood is given group A blood, their anti-A antibodies will attack the group A cells. This is why group A blood must never be given to someone who has group B blood and vice versa.

The Rh system
Red blood cells sometimes have another antigen, a protein known as the RhD antigen. If this is present, your blood group is RhD positive. If it’s absent, your blood group is RhD negative.

This means you can be 1 of 8 blood groups:

1. A RhD positive (A+)A

2. A RhD negative (A-)

3. B RhD positive (B+)

4. B RhD negative (B-)

5. O RhD positive (O+)

6. O RhD negative (O-)

7. AB RhD positive (AB+)

8. AB RhD negative (AB-)

In most cases, O RhD negative blood (O-) can safely be given to anyone. It’s often used in medical emergencies when the blood type is not immediately known.

It’s safe for most recipients because it does not have any A, B or RhD antigens on the surface of the cells, and is compatible with every other ABO and RhD blood group.

Giving blood
Most people are able to give blood, but only 1 in 25 people actually do. You can donate blood if you:

1. Are fit and healthy

2. Weigh at least 50kg (7st 12lb)

3. a Are 17-66 years old (or 70 if you’ve given blood before) are over 70 and have given blood in the last 2 years.

Let know all this and let help our family and friends know by sharing to them.