Blood Group Systems Flashcards
When was circulation of blood discovered?
17th century
What type of blood did early transfusion involve?
Animal
When was the first transfusion give, who was it given by and what was it used to treat?
1818
Dr James Bundell
Treated Post-partum haemorrhage.
Why were blood transfusions so risky from 1818-1845?
The ABO blood systems were not properly understood.
Transfusions were also open vein and did consider anti-coagulation.
When and by who were the ABO blood groups first discovered?
1901 by Karl Landsteiner.
How did Karl Landsteiner contribute to blood grouping?
He made compatibility studies which lead to safer blood transfusions. He also discovered the ABO blood grouping system.
What is the difference in transfusion time between the 1940s and now and why?
Blood transfusions were often lengthy in the 1940s but now only last up to 4 hour to prevent bacterial build up.
What were the issues with blood transfusions in the 1940s and why did these occur?
Bacterial build up often occurred because the transfusions were carried out over such a Long period of time.
Transfusions often lead to clotting because the blood wasn’t anti-coagulated very well.
In the 1940s, what were blood transfusions mainly used to treat?
Gastrointestinal problems, especially in men.
Define antigen.
Any substance, which in appropriate biological circumstances, can stimulate an immune response.
What are the antigens when on the topic of blood grouping systems?
Antigens on the surface of the membranes of red blood cells.
Define antibody
Proteins occurring in body fluids which are produced in response to the introduction of a foreign antigen.
Define agglutination.
When Erythrocytes are joined by cross-linking of antibody molecules.
How is agglutination different from clotting?
Agglutination does not activate a clotting cascade.
How is agglutination helpful in blood grouping?
It is used to determine what blood group antigens are present in the red blood cells and what red cell antibodies are present in the blood plasma.
What is Landsteiner’s law?
Antibodies are always preset in a healthy person’s plasma against antigens not present on their red cells.
What % of the population are blood type A, B or AB?
55%
Why are most fatal transfusion caused by ABO incompatibility?
ABO antibodies are capable of producing intravascular haemolysis.
Where do we get A or B blood genes from?
Inherited from out parents.
How does a precursor substance become an A or B antigen?
The precursor substance which coats all red blood cells produces H transferase which causes the precursor substance to convert to a H antigen. Depending on the A or B gene present, the A or B transferase enzyme will convert the H antigen to a A or B antigen.
What causes the OO genotype?
The OO genotype produces non-functional transferases and therefore the H antigen is left unchanged and doesn’t become A or B.
What are Immunodominant sugars in terms of blood grouping?
The different A, B or H transferases which determine the antigen type produced.
Why are the different transferases with determine the antigen type immunodominant?
They form the antigenic part of the molecules.
How do A and B gene alleles work together when they are inherited?
They are Codominant.
How does the O allele for together with other alleles when inherited?
It is recessive.
Why do different ethnic groups express different antigens and antibodies more frequently?
Natural selection has forced different ethnic groups to select different antigenic makeup due to their different environment and different diseases in these environments.
In terms of COVID-19, which blood group is most likely to need to be hospitalised?
A
How do ABO antibodies cause intravascular lysis?
Anti-A, Anti-B and Anti A,B antigens can bind to A or B antigens and become haemolytic in vivo. This is caused by activation of the complement pathway to completion.
What is the universal red cell donor?
Group O
What is the universal red cell recipient?
Group AB
What is the universal plasma donor group?
Group AB
What is the universal plasma recipient group?
Group O
By what age are full strength ABO antibodies achieved?
Age 5
When may ABO antigens be in low numbers?
Below 5 years of age and in old age.
What is meant by a ‘high titre’ when referring to blood grouping?
People with a very high level of their specific antibody type.
Why do people often have a ‘high titre’?
High antibody strength of the mother due to giving birth to multiple babies of different blood types. This increases the antibody strength of the children.
Often has no explanation.
How is ABO Haemolytic disease of the foetus and new-born often caused?
Mothers who have had many babies of blood types A, B or AB often produce IGG antibodies which can pass through the placenta and cause haemolytic diseases of the new-born.
Why are group AB the universal plasma donor?
They have no antibodies.
What is the main use of group AB plasma donation?
It is sent to the military for emergency situations.
Why is group O the universal plasma recipient?
Because they have both A and B antibodies.