What is antigen?

antigen is a protein that is present on the surface of red blood cells. This antigen is part of the ABO Blood Group, which is the most important blood group system when someone receives blood transfusion. The ABO Blood Group was discovered in 1900 by Austrian scientist Karl Landsteiner, who later won the Nobel Prize for his work.

Landsteiner's discovery was the existence of three blood types, classified on the basis of the presence of antigens, which he described as A, B and O. In 1902, another research group discovered the existence of the fourth type, with red blood cells that express both A and B. Someone who has B antigen has Blood B, while someone with antigen A and B has blood type AB. People with blood type shed or antigen or antigen B.

in antigen and is about twenty different subtypes. Most of these subtypes areVery rare. More than 99% of people have either A1 or A2; Subtype A1 is the most common and is present in approximately 80% of people. The A1 and A2 subtypes are so similar that they may not be distinguished for transfusion purposes. Some of the other subtypes are sufficiently different to complications when blood is written, but these subtypes are so rare that such problems are very rare.

For the most part, ABO antigen differences are only important in situations where an individual requires blood transfusion. Before someone receives blood transfusion, medical staff giving transfusion must know the blood type of the recipient. This is because the immune system creates antibodies against ABO antigens that are not expressed from red blood cells.

For example, in the case of someone with blood type A, the red blood cells expresses antigen. The immune system of this person creates antibodies against B antigen at the beginning of life, usually in the first or two years. The final result is that if someone with blood type and gets blood transfusion from someone withBlood B, antibodies from the recipient's immune system destroy the transfused red blood cells.

Therefore, the recipient of a blood -type transfusion must obtain a blood transfusion or type of o o. This is because these are the only types of blood that do not provide an immune response. Similarly, type A blood can only be donated to someone with blood type A or AB, due to the presence of antidote to type antigen in people with type B or blood type.