The blood is separated into categories according to the presence of substances in the membrane surface surrounding the red blood cells.
These substances are chemically proteins are called antigens.
Each organization depending on the antigens of erythrocytes of blood tolerate any class, but destroys the “incompatible” cells, ie blood group different from their own, with serious consequences so dangerous to his life.
The antigens of the erythrocytes is too much, however, important clinically are those belonging to two antigenic systems, the ABO system and RHESUS system of which have been named the blood groups in man.
The ABO system is the first discovered in 1900 by Karl Landsteiner and indicates whether or not the substances A and B red blood cells.
Substances such antigens, or there are two together, or only one of them or none.
-When There are two, the group said AB
-When There is only the first, the group called A
-When There is only the B group called B
-When There is neither A nor B, the group is said 0
What about transfusions
Group AB individuals can receive blood groups A, B, and 0, while giving blood only AB group.
group 0 subjects intolerant (due to the simultaneous presence in the plasma of anti-A antibody and anti-B), but only the blood of the same group with them, and can give people of all other groups.
Statistical studies in the Greek population have shown the same frequency of blood groups in Europe which are as follows:
AB = 4.75%
A = 37.93%
B = 12.93%
0 = 44.39%
After antigenic ABO system, second in importance from a clinical point of view, comes the rhesus system also discovered by Karl Landsteiner in 1940.
Depending on the presence or not on the surface of red blood cells of Rhesus factor, that is as the substances A and B, an agglutinogen, red blood cells are called “AB, A, B, 0 / Rhesus positive and
AB, A, B, 0 / Rhesus negative
The frequency of blood groups on the Rhesus factor in the Greek population are:
Rhesus positive = 85%
Rhesus Negative = 15%
An individual rhesus – positive can draw blood from the same group, and in some cases blood Rhesus – negative.
Instead, individual Rhesus – negative should not accept blood Rhesus – positive.
If this happens during the first racking usually nothing happens. Anti-Rhesus substances will destroy massive red-positive in case of a second or other mis-transfusion risk of life of the patient.
Something similar can happen to women Rhesus – negative if pregnant fetus has inherited from his father Rh antigen.
In this case it is likely that nothing will not occur during the first delivery. In the next but deliveries preexisting blood maternal anti-Rh antibodies by following the opposite path, will pass through the placenta into the bloodstream of the fetus Rhesus – positive and may cause from mild jaundice, to serious or fatal damage to the body of the fetus .
The blood groups are inherited, therefore accompany the life of every individual from birth to death and is genetically determined.
The study of all systems of erythrocyte antigens of white blood cells and serum proteins (and not just the ABO and Rh systems) serves to control disputed paternity.