Lately we are talking about a lot of the “super donor” of Australian blood and plasma James Harrisonnicknamed “golden arm” and died last February 17 at the age of 88, because his blood contained a antibody or immunoglobulin (IG) very rare, the Anti-D IGor Rhig, who made it possible to save thousands – perhaps even millions – of children from a fetal disease called Hemolytic disease of the newborn. Do you think that Harrison has held the record of the amount of plasma donated until 1100 donations within several decades until 2022.
When the blood group of a mother is negative RH and the fetus is a positive RH, the maternal immune system recognizes it as foreign and begins to produce antibodies against fetal red blood cellswith serious consequences, such as anemia, for the unborn child. Thanks to James Harrison and other donors it is possible to administer anti-d to Rh women to prevent their immune system producing these antibodies and attacks the red blood cells of the fetus.
What is and how anti -D immunoglobulin works
Anti-D immunoglobulin is in all respects a antibody which is administered during a pregnancy, and prevents the maternal immune system recognizes the antigen D on the red blood cells of the fetus. In practice, it hides and protects fetal red blood cells as a “foreign cloak”. In this way, the mother does not produce antibodies that could attack the red blood cells of the fetus.
The mechanism of action is not yet very clear, but it seems that anti-D IG still neutralizzi any fetal antigen Positive rhd with which maternal blood could come into contact. The administration of anti-d immunoglobulin is also useful in other pathologies, such as the Autoimmune trombocytopenic purplein which the immune system recognizes its red blood cells as strangers, and therefore attacks its red blood cells.
But what does “positive Rhd” mean? We all know that blood groups are divided into A, B, AB and O and in Rh positive and negative. The latter are linked to the presence or absence of the Rhesus factor, a antigen protein, that is, a molecular complex, which we could imagine as one plate attached to the red blood cell membrane. Actually, of Rhesus factors there are different ones, but to define the positivity or negativity of the blood group is in particular the Rhesus D factor.
If a person presents the antigen D on red blood cells, he has a blood group positive (Rh+), if the antigen d lacksthen has a blood group negative (Rh-).
What the hemolytic disease of the newborn consists during pregnancy
For the first pregnancy, the incompatibility between maternal and fetal blood group usually does not represent a very serious problem: a bit like it happens for allergies, the first contact with the antigen produces antibodies, but still does not give serious effects.
The greatest problem can arise during one second pregnancy in which the mother is Rh+ and the baby is Rh-: At this point they are Already present anti-d antibodies in the maternal bloodstream that can enter the fetal one and attack red blood cells. This leads to a serious pathology called Hemolytic disease of the newborncharacterized by the destruction of fetal red blood cells, as suggested by the name emo And lisiliterally “breaking of the sangAnd”.
It can give problems both fetal and at the time of birth: the newborn can be pale, jaundiced (skin and sclera of the eyes take on a yellowish color) and can lead to severe anemia.
As a precision, the hemolytic disease of the newborn could occur in all cases in which maternal and fetal blood group are incompatiblefor example if the mother is of group 0 and the fetus is of group B, but it is very rare and usually less serious cases. It is theincompatibility of the RHD factor To determine most of the cases of this disease and cause more serious damage, so much attention is paid to it.
How to prevent the hemolytic disease of the newborn
This is where they come into play James Harrison And other donors like him. During pregnancy the Coombs test To check that the maternal and fetal blood group are compatible. In case of incompatibility, women Rh- are administered intramuscularly Anti-D Human Immunoglobulins (obtained precisely from the plasma of donors and donors) who, as we have seen, prevent the maternal immune system produces antibodies against the red blood cells of the fetus. This administration is called Anti-D immunoprophylaxis. In fact, the generosity of Harrison and other donors like him has allowed and still allows to save millions of lives.
