Blood Transfusion Flashcards
Why transfer blood?
- Bleeding
- Failure of production
- Excess rate of destruction
Blood groups arise from what?
Arise from antigens:
- Antigens provoke immune response
What could happen when you receive blood from someone without matching the correct group?
If you receive blood from someone else could provoke the formation of antibodies:
- Creates immunological memory so second response is a lot faster than the first
What are the different blood types with the ABO system?
- Type A
- Type B
- Type AB (has bone A and B antigens)
- Type O (has no antigens)
What antigens do AB and O blood groups have?
- Type AB (has bone A and B antigens)
- Type O (has no antigens)
What does the ABO gene code for?
ABO gene encodes glycosyltransferase:
- Sugar chains are added to this
- A and B genes code for transferase enzymes
- A antigen is N-acetyl-galactosamine
- B antigen is galactose
- O gene is non-functional allele (non-functional enzyme so adds nothing)
- A and B are dominant, O is recessive
What is the A antigen?
- A antigen is N-acetyl-galactosamine
What is the B antigen?
- B antigen is galactose
What is the O antigen?
- O gene is non-functional allele (non-functional enzyme so adds nothing)
Which of A, B and O are dominant/recessive?
- A and B are dominant, O is recessive
What antibodies are produced for the following blood groups:
- group A
- group B
- group AB
- group O
- If blood group A
- Antibodies against B
- If blood group B
- Antibodies against A
- If blood group O
- Antibodies against A and B
- If blood group AB
- No antibodies against A or B
How does the development of antibodies against antigens from other blood groups arise without exposure to that blood?
This arises because of immune tolerance:
- Tolerance against self-antigens
- Encounter other A, B or O antigens as are also found on naturally occurring bacteria in the gut, so develop antibodies
- IgM antibody as the antigens are sugars and not proteins
- Have ability to fix complement, so makes reaction even more violent
- Thermal range of IgM important
Are the AB antigens sugars or proteins?
Sugars
What type of immunoglobulin is the antibody against A/B antigens?
- IgM antibody as the antigens are sugars and not proteins
- Have ability to fix complement, so makes reaction even more violent
- Thermal range of IgM important
Which blood group is most and least common in the UK?

From what blood groups can the following receive red cells from:
- group A
- group B
- group AB
- group O

What does FFP stand for?
Fresh frozen plasma
From what blood groups can the following receive FFP from:
- group A
- group B
- group AB
- group O

What is the rhesus antigen?
This is a protein antigen that forms a pore
What genes are involved in the rhesus antigen?
- RhD gene
- Genotypes DD, Dd or dd
- RHCE gene
- Genotypes Cc, Dd, Ed; R1R2, rr etc etc – do not need to know this
What are the various genotypes for the RhD gene?
- Genotypes DD, Dd or dd
What can RhD negative individuals produce in response to the rhesus antigen?
RhD negative individuals (dd) can make anti-D antibodies to RhD+ cells:
- Can occur during transfusion or pregnancy
- Can cause transfusion reactions of haemolytic disease of newborn
What is done before donating blood?
- Extensive ‘behaviour’ screening
- Medical history, previous transfusion
- Sex, age, travels, tattoos etc
What are blood donors screened for?
- Screened for HepB/C/E, HIV and syphilis
- Variability screening for HTLV1, malaria, West Nile virus, Zika virus if travelled

