In 1902, the Austrian physician Karl Landsteiner and some scientists managed to classify human blood into four types: A, B, AB andO. During research, it was found that some blood types were incompatible, and this incompatibility was due to a immunological reaction between substances dissolved in blood plasma and substances present in blood cells, the Red Cells. The agglutinating substances of the red blood cell membrane were then called agglutinogens; and the plasma agglutinating substances of agglutinins. Below we can see a chart illustrating the agglutinogens and agglutinins of the ABO system.
blood group |
agglutinogens (in red blood cells) |
agglutinins (in blood plasma) |
THE |
THE |
anti-B |
B |
B |
anti - A |
AB |
AB |
|
O |
|
anti - A and anti - B |
The dblood type discovery was very important, as before that many accidents were caused, including patients dying because they received blood incompatible with their own. Therefore, it is extremely important that, before having a blood transfusion, the person's blood type is known.
if a person has the blood type A, that presents agglutininanti-B in the plasma, she cannot receive type B or type AB blood. The same happens with a person who has the blood type B, that, for presenting agglutininanti-A in the plasma, cannot receive type A or type AB blood. Who has the blood type ABhas no agglutinins in plasma that's why can receive any type of blood, which is why it is called universal receiver. However, people who have the blood type O is that have both types of agglutinins in plasmacan only receive type O blood. On the other hand, these people can donate blood to any individual, as do not have A and B agglutinogens, and therefore are called universal donors.
blood group |
Can receive blood from: |
You can donate blood to: |
THE |
A and O |
A and AB |
B |
B and O |
B and AB |
AB |
A, B, AB and O |
AB |
O |
O |
A, B, AB and O |
Rh system of blood groups
O RH system was also discovered by Karl Landsteiner and his team, in an experiment with a monkey of the species rhesus. They observed that when they injected this monkey's blood into guinea pigs, the guinea pigs produced antibodies, which they called anti-Rh (short for anti-rhesus).
Doing this same experiment, but with human blood, the researchers found that 85% of human blood samples tested with the Rh antibody suffered agglutination, which suggests the presence of Rh antigen in the blood. People who had red blood cells agglutinated by Rh antibody were called Rh positive (Rh+), indicating that their red blood cells have a monkey-like antigen, the Rh factor. The red cells of the remaining 15% did not agglutinate and therefore were called Rh negative (Rh-), indicating the absence of the Rh factor in their red blood cells.
To find out if a person is Rh positive or negative, just mix a drop of the person's blood with a solution with Rh antibodies. If the red cells clump together, this person has blood Rh+; if they don't agglutinate, this person has blood Rh-.
By Paula Louredo
Graduated in Biology
Source: Brazil School - https://brasilescola.uol.com.br/biologia/genetica-problema.htm
