The four blood groups as we know them today are the result of 40,000 years of evolution of the human species.
The man, who was originally exclusively a hunter (group O), evolved, first (about 20,000 years ago) learning to cultivate the land and feed on its fruits (group A) and subsequently (about 15,000 – 10,000 years ago) , on the heights of the Himalayas, becoming a nomad and taking care of livestock (group B). Finally, about 1,000 years ago, the AB group was formed, the only one not to be the effect of an evolutionary process, but of the mixture between the sedentary inhabitants of the Caucasian areas and the nomads from Mongolia.
What is a blood group?
When the human body is attacked by a pathogen (viruses, bacteria, etc.), it triggers a defense mechanism that attacks and neutralizes these antigens thanks to the presence of plasma proteins called antibodies.
On the surface of the red blood cells two different antigens can be distinguished: the antigen A and the antigen B. In the same way in the plasma anti-A antibodies and anti-B antibodies can exist. Both neutralize and kill red blood cells carrying the corresponding antigen.
Each blood group is therefore characterized by the presence of specific antigens and the corresponding antibodies:
- group A contains A antigens and anti-B antibodies
- group B contains B antigens and anti-A antibodies
- the AB group contains antigens A, antigens B and none of the corresponding plasma antibodies
- group 0 is antigen free but contains both anti-A and anti-B antibodies
It’s clear that:
- each individual does not have antibodies to the antigens present in his blood, otherwise he would self-destruct;
- each individual has antibodies to fight the antigens he does not have.
There are, therefore, 4 possible combinations:
- in the red blood cells antigen A is present in the plasma, then the anti-B antibody. the individuals in question constitute the GROUP A.
- in the blood cells is present the antigen B, in the plasma we therefore find the anti-A antibody. blood type is B.
- in the red blood cells are present both the antigen A and that B. In the plasma none of the two antibodies will be present. The
blood is from the AB group.
- In the blood cells there is no antigen in the plasma so both the anti-A antibody and the anti-B antibody are present. the individuals in
question belong to the GROUP 0 (zero).
The subject carrying the AB blood group is the most fortunate given that, being free of specific antibodies, it can receive blood from both type A, B, AB and 0 (universal receiver).
contrary speech for those with type 0 blood that can only receive similar blood (universal donor).
The individual of group A can instead receive blood from groups A and 0; while type B blood is compatible only with groups B and groups 0
If these combinations are not respected the antibodies present in the plasma (agglutinins) attack the red blood cells of the transfused blood, neutralizing them (agglutination reaction) and forming small lumps that occlude the blood vessels causing very serious damage to the body.
The blood group to which we belong is inherited from our parents and is immutable from birth to death. The frequency of these groups varies according to the ethnicity of the population: in England about 40% of individuals are in group A and only 10% are in group B; in India group A is present in 27% of cases and group B in 50%. Blood group AB is the rarest in Europe.
Subsequent research into Landsteiner’s studies revealed the existence of other antigens that are important to take into account in the practice of transfusions. Among these, the most important is the so-called Rh factor, an antigen discovered by a group of researchers led by the same Landsteiner, around 1940.
The discovery of the Rh factor was made possible by studies conducted on a group of Rhesus macaques, from which the name Rh was derived.
In the circulatory stream, regardless of the blood group, the Rh antigen may be present or be completely absent. In the first case we speak of Rh positive (Rh +), in the second case of Rh negative (Rh-) blood.
This is it for part one of this mini series, Next week we will continue our in depth analysis by investigating the affinities between blood groups and nutrition. See you all soon.
Franco defines itself as a person trapped in a sedentary lifestyle, however, he is an avid fitness “addict” and like, many more in his environment spends vast parts of his leisure time on a gym, running, cycling.