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Immunology and Haematology > Blood Transfusion > Flashcards

Blood Transfusion Flashcards

1
Q

Why transfer blood?

A
  • Bleeding
  • Failure of production
  • Excess rate of destruction
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2
Q

Blood groups arise from what?

A

Arise from antigens:

  • Antigens provoke immune response
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3
Q

What could happen when you receive blood from someone without matching the correct group?

A

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
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4
Q

What are the different blood types with the ABO system?

A
  • Type A
  • Type B
  • Type AB (has bone A and B antigens)
  • Type O (has no antigens)
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5
Q

What antigens do AB and O blood groups have?

A
  • Type AB (has bone A and B antigens)
  • Type O (has no antigens)
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6
Q

What does the ABO gene code for?

A

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
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7
Q

What is the A antigen?

A
  • A antigen is N-acetyl-galactosamine
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8
Q

What is the B antigen?

A
  • B antigen is galactose
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9
Q

What is the O antigen?

A
  • O gene is non-functional allele (non-functional enzyme so adds nothing)
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10
Q

Which of A, B and O are dominant/recessive?

A
  • A and B are dominant, O is recessive
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11
Q

What antibodies are produced for the following blood groups:

  • group A
  • group B
  • group AB
  • group O
A
  • 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
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12
Q

How does the development of antibodies against antigens from other blood groups arise without exposure to that blood?

A

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
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13
Q

Are the AB antigens sugars or proteins?

A

Sugars

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14
Q

What type of immunoglobulin is the antibody against A/B antigens?

A
  • 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
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15
Q

Which blood group is most and least common in the UK?

A
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16
Q

From what blood groups can the following receive red cells from:

  • group A
  • group B
  • group AB
  • group O
A
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17
Q

What does FFP stand for?

A

Fresh frozen plasma

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18
Q

From what blood groups can the following receive FFP from:

  • group A
  • group B
  • group AB
  • group O
A
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19
Q

What is the rhesus antigen?

A

This is a protein antigen that forms a pore

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20
Q

What genes are involved in the rhesus antigen?

A
  • RhD gene
    • Genotypes DD, Dd or dd
  • RHCE gene
    • Genotypes Cc, Dd, Ed; R1R2, rr etc etc – do not need to know this
21
Q

What are the various genotypes for the RhD gene?

A
  • Genotypes DD, Dd or dd
22
Q

What can RhD negative individuals produce in response to the rhesus antigen?

A

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
23
Q

What is done before donating blood?

A
  • Extensive ‘behaviour’ screening
  • Medical history, previous transfusion
  • Sex, age, travels, tattoos etc
24
Q

What are blood donors screened for?

A
  • Screened for HepB/C/E, HIV and syphilis
  • Variability screening for HTLV1, malaria, West Nile virus, Zika virus if travelled
25
Q

Describe the process of collecting from blood donors?

A
  1. Skin carefully cleaned
  2. Diversion pouches to separate first dose of skin and bacteria for sterile

Can also be connected to machine (aphresis donors) to collect specific components of blood

26
Q

What are the components of blood?

A
27
Q

What are indications for red cell transfusions?

A
  • Severe acute anaemia, which could otherwise cause organ damage
  • Correctable anaemia
    • Improve quality of life
  • Prepare patient for surgery or speed up recovery
  • Reverse damage caused by patients own red cells
    • Sickle cell disease
28
Q

1 unit transfusion of red cells increases haemoglobin level by?

A
  • 1 unit increments the haemoglobin by about 5g/L
29
Q

How are red cells stored and over what time are they transfused?

A
  • Stored at 4 degrees
  • Over 2-4 hours
30
Q

1 dose of platelets increases levels by?

A
  • 1 dose increases increment by 30.109L
31
Q

How are platelets stored and how long are they transfused over?

A
  • Stored at about 22 degrees, shelf life 7 days
  • Transfuse over 20-30 minutes
32
Q

What are indications for platelet transfusion?

A
  • Massive haemorrhage
    • Keep platelet count above 75x109L
  • Bone marrow failure
    • Platelet count <10-15x109L
  • Prophylaxis for surgery
    • Minor procedures 50x109L
    • Major procedure 80x109L
    • CNS or eye surgery 100x109L
  • Cardiopulmonary bypass
    • Use only if bleeding
33
Q

What are different plasma components for transfusion?

A
  • Fresh frozen plasma
    • 1 unit from 1 unit of blood
    • Stored frozen, allow 30 minutes to thaw
    • Indications
      • Massive haemorrhage (1:1 ratio)
      • DIC with bleeding
      • Prophylactic
  • Cryoprecipitate
    • Give 1-2 pools if fibrinogen <1g/dL
    • Stored frozen, allow 20 minutes to thaw
34
Q

What are indications for transfusion of FFP?

A
  • Massive haemorrhage (1:1 ratio)
  • DIC with bleeding
  • Prophylactic
35
Q

What are indications for cryoprecipitate?

A
  • Give 1-2 pools if fibrinogen <1g/dL
36
Q

Describe the process of choosing compatible blood?

A
  1. Send blood sample to blood bank
  2. Need to send 2 samples unless emergency
  3. Request group and screen, or cross matching if you want blood
37
Q

What is done when you request a “group and screen” of blood?

A

Group and screening:

  • ABO and RhD type
  • Checked against historical records
  • Screen for allo-antibodies in serum
38
Q
A
39
Q

What is Coombs test?

A
  • Detecting antibodies on surface of red cells
  • If IgM on surface cells clump together due to pent nature, if IgG they do not
  • Can add anti-human immunoglobulin, because is bi-valent, will allow these red cells to clump together and detect IgG
40
Q

What does Coombs test allow us to detect?

A
  • Direct Coombs test
    • Autoimmune haemolytic anaemia
    • Passive anti-D
    • Haemolytic transfusion reactions
  • Indirect Coombs test
    • Cross matching
41
Q

What are some of the various blood grouping systems?

A
  • >21 blood group systems
    • ABO, Rh, Kell, Duffy, MN, P, Lewis, Lutheran are some examples
42
Q

What does HDN stand for?

A

Haemolytic disease of foetus and new-born

43
Q

What is HDN?

A

Mother can develop antibodies against foreign antigens carried by their babies, that are encoded by paternal alleles:

  • Most important is RhD system
    • 15% of mums RhD negative, if father is positive (as most men are) then there is risk of disease
    • If red cells leak across placenta, or at birth, mother will form antibody (usually IgG as is for protein and so can cross placenta) affecting future pregnancy
44
Q

When can rhesus cause complications in pregnancy?

A
  • 15% of mums RhD negative, if father is positive (as most men are) then there is risk of disease
  • If red cells leak across placenta, or at birth, mother will form antibody (usually IgG as is for protein and so can cross placenta) affecting future pregnancy
45
Q

What are complications of HDN?

A
  • Death
  • Brain damage
  • Jaundice
46
Q

Describe the treatment for HDN?

A
  • Prevention using prophylactic anti-D if mum is RhD negative
    • Routine at 28 and 40 weeks
  • Treatment by careful monitoring
    • Antibody titres
    • Doppler US
    • Intrauterine transfusions
47
Q

What is a similar disease to HDN, but for platelets instead of red cells?

A

A similar disease for platelets instead of red cells is neonatal alloimmune thrombocytopenia (NAIT)

48
Q

What does NAIT stand for?

A

Neonatal alloimmune thrombocytopenia

49
Q

What cellular therapies do blood transfusion services offer?

A
  • Leucpheresis
    • Stem cells
      • For transplantation
    • Lymphocytes
      • For immunotherapy
      • CAR-T cells
  • ‘Other banks’
    • Bone, milk, tendons, heart valves, faecal
    • Islet cells, mesenchymal stem cells
  • Gene therapies

Immunology and Haematology (23 decks)

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