Here is all about the ABO blood group –
ABO Blood Group and History of Blood Transfusion –
- Blood transfusion experiments have been performed for hundreds of years. Many patients died and it was not until 1901, when Ryan Strian Carl Landsteiner discovered human blood groups, that it became safe to transfuse blood.
- He discovered that mixing blood from two individuals could cause blood to become unstable.
- Rough RBC cracked and can cause a toxic reaction. This can be fatal. Carl Landsteiner discovered that blood clotting is an immune response that occurs when blood transfusions have antibodies against donor blood cells.
- The work of Carl Landsteiner made it possible to determine blood types and thus paved the way for a safe transfusion of blood.
- For this discovery, he was awarded the Nobel Prize in Physiology or Medicine in 1930. About 4-6 liters of blood circulate in the body of an adult man.
- Blood contains some types of cells that float around in a fluid called plasma. Red blood cells (RBCs) contain hemoglobin, a protein that binds oxygen, RBCs transport oxygen, and remove carbon dioxide from tissues.
- White blood cells fight infection. Platelets help the blood to clot if you have a wound for example. Plasma contains salts and a variety of proteins.

What are the different blood groups?
- The difference in human blood is due to the presence or absence of certain protein molecules called antigens and antibodies.
- Antigens are located on the surface of RBCs and antibodies are present in the blood plasma.
- Individuals have different types and combinations of these molecules.
- Depending on what blood group you are, what you inherited from your parents.
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Today more than 20 genetically determined blood group systems are known,
The ABO and Rhesus (RH) systems are the most important used for blood transfusions. Not all blood groups are compatible with each other. Mixing incompatible blood groups leads to blood clots or aggregation, which is dangerous for individuals. A.B.O. According to the blood typing system, there are four different types of blood: A, B, AB or O (null).
Blood group A – If you belong to blood group A, your blood plasma contains antigens on the surface of your RBC and B antibodies.
Blood group B – If you belong to blood group B, you have B antigens on the surface of your RBCs and those antibodies in your blood plasma.
Blood group AB – If you belong to blood group AB, you have both A and B antigens on the surface of your RBCs and no A or B antibodies in your blood plasma.
Blood group O – If you belong to blood group O (null), you have neither A or B antigens on the surface of your RBC but you have both A and B antibodies in your blood plasma.
ABO inheritance and genetics –
- The ABO gene is autosomal (the gene is not on either chromosome).
- The ABO gene is located on the locus chromosome 9.
- A and B blood groups are dominant on the O and blood groups.
- Group A and B genes are co-dominant.
- Each person has two copies of the coding genes for their ABO blood group (one maternal and one maternal origin).
Rhesus (RH) system –
- Well, it becomes more complicated here, because there is another antigen to consider – the RH antigen RH gene, located on the short arm of chromosome I.
- Some of us have Rh, some don’t.
- If it is present, the blood is RHD positive, if not it is RHD negative.
- So, for example, some people in group A will have, and so will be classified as A + (or A positive). When it is not, it is A- (or A-negative).
- And so it goes for groups B, AB, and O.
- They are named after the rhesus monkey in which they were first discovered.
- RBC antigens that are “Rh-positive” express designated D.
- 85% of the population is RHD positive, another 15% of the population has RHD negative blood.
Why is Rh incompatibility so dangerous?
The results of producing a child-like Rh-negative female and Rh-positive male, in general, will probably be positive Rh-positive. 1st pregnancy is not affected, 2nd pregnancy and subsequent births will result in severe jaundice, HDN related anemia. The woman is given RH-IG to prevent this phenomenon.
Who can receive blood from whom?
People with blood group O are called “universal donors” and people with blood group AB are called “universal receivers”.

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