Rh factor

Rh factor

Rhesus factor is an inheritable property of red blood cells (erythrocytes). If the factor is present, it is called Rh-positive (Rh +) blood, it is not Rh-negative (Rh) blood.

The Rhesus factor acts like an antigen, d. that is, in Rh-negative blood, antibodies are formed against the Rhesus factor. Therefore, Rhesus factor plays a crucial role in blood transfusion and pregnancy. Donors and recipients of blood must not only have the same blood group but also the same Rhesus factor. If this is not the case, there are incompatibility reactions that can be fatal.

The rhesus factor

The Rhesus factor is an antigen that is located on the surface of the red blood cells (erythrocytes). The erythrocytes are subdivided into four blood groups A, B, AB and 0 according to specific surface properties.

People whose blood cells have no Rhesus factor are referred to as Rh negative (Rh-). Rh-positive (Rh +) are those people in whom the Rhesus factor can be detected.

Antigens - and thus the Rhesus factor - cause the production of antibodies as soon as they enter a foreign body.

Discovery and meaning of Rhesus factor

The Rhesus factor was discovered in 1940 by KARL LANDSTEINER and ALEXANDER WIENER in Rhesus monkeys. The actual goal of the study was to produce antibodies against rhesus monkey erythrocytes in rabbits and guinea pigs. The scientists discovered that in humans, the same antibodies lead to incompatibility reactions, namely to a clumping (agglutination) of the blood cells.
The Rhesus factor inherits according to Mendelian rules.
Much of the world's population has Rh-positive blood.

The discovery of rhesus factor plays a crucial role in blood transfusions and pregnancies.

In the case of blood transfer, the donor's blood group and Rhesus factor must match the recipient's blood type and Rhesus factor. If this is not the case, the blood clumps up and is thereby destroyed.
Pregnancy poses a risk if the mother is Rh-negative and carries a Rh-positive child. Assuming this is the first pregnancy of the mother, at birth, a greater amount of Rh-positive blood of the baby enters the Rh-negative bloodstream of the mother. As a result, antibodies are produced in the blood of the mother, which destroy the blood of the child. This process is safe for the first child, but there is a risk for all subsequent Rh-positive children. The so-called memory cells in the bloodstream of the mother ensure that in case of a second pregnancy with a Rh-positive child antibodies against the blood of the child can be formed very quickly. The antibodies pass through the placenta into the bloodstream of the child. The consequence is a destruction of the red blood cells of the child and there is a blood disease in the fetus.

The hemoglobin of the agglutinated (clumped) blood cells is degraded and bilirubin is formed. Bilirubin damages the child's brain and leads to yellowing of its skin and tissue (jaundice). In return, the embryo quickly produces large quantities of new blood cells, causing the liver and spleen to swell up considerably. Without an immediate blood exchange with Rh-positive blood, the embryo has no chance of survival and dies. a. of heart failure.

Prevention: Today, prenatal examinations can resolve 99% of all Rh-negative mother and Rh-positive pregnancy problems. In this case, the mother is injected before the formation of antibodies and memory cells, a Rh-positive immunoglobulin. The immunoglobulin removes childish red blood cells as they enter the maternal bloodstream. This can prevent the immune reaction in the mother. This process should be repeated every pregnancy.