preview:• They are unusual in that the natural occurring antibodies occur in the plasma of subjects who lack the corresponding antigen even if they’ve never been transfused or been pregnant.
• The most important of these are anti-A and anti-B, they are usually IgM and react optimally at cold...
10. Overview of the NHS Blood and Transplant Service
1
A campaigner Jason Evans’s father died in 1993, his father contracted hepatitis and HIV
whilst he was at hospital. It focusses on a meeting of 50 directors from UK haemophilia
centres as well as the department of health official in November 1974.
When the UK ran low on factor 8, it was imported from the US so people who were known
to have risky lifestyles, like prisoners, were paid cash for blood donations.
Health official in 1974 allowed people to be infected with contaminated blood despite
knowing it was making people ill according to the meeting minutes released under the
freedom of information act.
Official knew haemophiliacs were being given dangerous blood from the US and it was giving
them hepatitis however nobody raised the alarm to stop the spread of the blood, instead
officials hoped that the imported goods would not get a bad name.
This meant that batches of contaminated bloods were continuously given to innocent
people in the 70s and 80s without being told the blood was risky.
This has been labelled the worst treatment disaster in the history of the NHS.
Most of the patients infected were diagnosed with haemophilia which prevents blood from
clotting properly and can be measured with regular injections of factor 8 but this in fact gave
them a whole host of other blood borne infections.
.
.
3 – …and this antigen is capable of causing an immune response.
Pre-transfusion compatibility testing is used to prevent incompatible red blood cell
transfusions that could lead to immune haemolytic reactions.
Blood groups are antigens and by definition a molecule can’t be an antigen unless it is
recognised by an antibody therefore all blood group specificities are defined by an antibody.
.
Some of the groups only contain one antigen (H antigen) whereas others contain multiple
(rhesus system).
The ABO blood group antigens are unique – they have a carbohydrate and protein structure
protruding from the red cell membrane.
In terms of transferring blood or blood-based organs there has to be a process in place
which has to be appropriate, acceptable (will survive in the recipient’s circulation), the
transfusion has to be lifesaving or has to be essential e.g., in hereditary or chronic
conditions.
.
Blood groups hold great clinical importance in blood transfusions and in transplantation –
the discovery of the ABO was probably one of the most important factors in making the
practice of blood transfusions possible.
Lots of blood group antibodies have the potential to cause rapid ABO destruction of
transfused RBCs bearing the corresponding antigen giving rise to a haemolytic reaction, it
might be a delayed reaction so it will occur a few days later.
Understanding more about these systems is really important.
All of them are able to cause a haemolytic transfusion reaction.
.
1492 – it was successful but after that there were a lot of deaths that were caused, during
that time it was deemed witchcraft, so they stopped.
, 10. Overview of the NHS Blood and Transplant Service
1665 – first successful blood transfusion recorded – he bled a dog almost to death and
revived it by transfusing blood form another dog via a tied artery.
1667 - …both survived the transfusion.
Between 1665 and 1668 there were lots of unsuccessful transfusions form animals to
humans as a result of this transfusions were outlawed due to the reactions and the
subsequent deaths that they were causing.
.
English obstetrician performed the first successful transfusion of human blood to a patient
for the treatment of a haemorrhage.
.
Karl Landsteiner drew blood from his co-workers, he separated cells and plasma and mixed
the cells and plasma of various people on glass tiles, he saw reactions between RBCs and
serum due to the presence of markers (we know them as antigens) on the RBCs and
antibodies in the serum and he saw that agglutination occurred when the RBCs were bound
by the antibodies in the serum.
He was able to identify 3 different patterns of reactivity and he called them A, B and C, we
now know them as the A, B and O system.
In 1902 one of his associates discovered blood group AB. These now represent the 4 major
blood groups within our ABO system.
.
AB is a universal acceptor.
O is a universal donor.
.
They are unusual in that the natural occurring antibodies occur in the plasma of subjects
who lack the corresponding antigen even if they’ve never been transfused or been pregnant.
The most important of these are anti-A and anti-B, they are usually IgM and react optimally
at cold temperatures (4°) although they are reactive at 37° as well.
Immune antibodies develop in response to the introduction of RBCs that possess antigens
that a person lacks, and this can occur during transfusion or pregnancy and these antibodies
are IgG, some IgM may develop in the early phase of an immune response – we’ve seen this
and talked about haemolytic disease of the new-born.
Immune antibodies can activate complement readily at 37° so we call them warm antibodies
and only IgG can pass from the mother to the foetus, transplacental are the most important
antibodies in rhesus D, ABA and anti-D, any kind of ABO incompatibility can cause a fatal
transfusion reaction.
.
The term rhesus positive and negative refers to the presence or absence of the D antigen.
This table summarises compatible blood types including then the rhesus positive and
negatives as an addition to the previous table.
The + refers to rhesus positive.
O- can donate blood to absolutely everyone however they can only receive blood from O-.
AB+ blood type is the universal acceptor as they can receive blood form all different blood
types, but they can only donate their blood to those that are AB+.
.
.
What stops cells form sicking together and to vessel walls? They have repulsive forces
generated by negative charges on the RBC surface, these occur due to the presence of
carboxylic groups of sialic acid in the cell membrane, the charges create a repulsive electric
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