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Human Organs and Tissues > Blood Group Compatibility > Flashcards

Blood Group Compatibility Flashcards

1
Q

Who discovered ABO blood groups ?

A

Karl Landsteiner in 1901

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2
Q

How were ABO blood groups discovered?

A

Discovered based on agglutination reactions between one persons blood and another

blood transfusion between individuals of different blood groups led to red cell destruction. This did not occur between individuals of the same blood group.

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3
Q

When was the first successful blood transfusion performed?

A

at the Mount Sinai Hospital in NY in 1907

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4
Q

ABO antigens are what type of antigens?

A

carbohydrate antigens

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5
Q

What gene codes for the O or H antigen backbone?

A

Fucosyl transferase 1 (FUT1)

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6
Q

What does glycosyltransferase A or GTA gene code for

A

N-acetylgalactosamine or the A antigen being added

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7
Q

What is the B antigen? what gene codes for it?

A

galactose

coded for by glycosyltransferase B

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8
Q

What results in O blood group?

A

lack of both GTA and GTB

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9
Q

What kind of expression is there with the GTA and GTB genes?

A

co-dominant expression

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10
Q

What is the Bombay phenotype?

A

a mutation in FUT1 results in a defective H antigen so they are automatically O phenotype regardless of the GTA/GTB genotype

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11
Q

How do people develop antibodies against the A/B/or both antigens that they themselves do not have?

A

Due to exposure to similar carbohydrates on gut bacteria

- mostly IgM but some IgA and IgG

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12
Q

When do infants develop anti AB antigens?

A

only between 6-12 months of age

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13
Q

What happens during an acute hemolytic transfusion reaction?

A

Rapid intravascular destruction of transfused RBCs by preformed antibody

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14
Q

What kind of preformed antibodies against RBCs exist? what do they do?

A

IgM class that fix complement

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15
Q

What happens following fixation of complement by IgM antibodies?

A

Intravascular hemolysis, release of free hemoglobin and pro-inflammatory cytokines

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16
Q

What are some symptoms of an acute hemolytic transfusion reaction?

A
  1. DIC
  2. Hypotension/Shock
  3. Acute renal failure
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17
Q

What is the mechanism for a hyperacute rejection reaction?

A
  1. Preformed antibodies bind to the A and or B antigens on the endothelial cells of the vasculature of the transplanted organ
  2. Antibodies activate the classical complement pathway
  3. products of complement and antibodies activate neutrophils
  4. Neutrophils degranulate and release lytic enzyme that damage the endothelium and expose the vessel wall
  5. MAC damages the endothelium
  6. platelets adhere to the vessel wall and form a clot (thrombosis) which blocks circulation
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18
Q

What are Rh antigens?

A

Glycoproteins expressed on RBCs

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19
Q

Where are the coding genes located for Rh antigens ? What gene

A

on chromosome 1

RHD

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20
Q

Explain the difference between RHD, RHCE and what the D antigen is

A

RHD gene codes for RhD or the D antigen

Lack of D antigen is referred to as d

RhD (D antigen) colloquially referred to as Rh

RHCE makes RHCE protein that comes in 4 variants:CE, Ce, cE and ce

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21
Q

RhD inheritance is…

A

dominant

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22
Q

What is erythroblastosis fetalis caused by

A

incompatibility between maternal and fetal blood antigens

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23
Q

What is the most common cause of erythroblastosis fetalis?

A

RhD incompatibility where the mother is Rh- and the fetus if Rh+

24
Q

What happens if fetal Rh+ blood cells cross the placenta into the Rh- mother?

A

Mother develops anti-Rh antibody which then crosses the placenta

25
Q

What happens when anti Rh antibodies cross the placenta back into the Rh+ infant?

A
  1. Fetus develops anemia
  2. Fetus can die due to heart failure (hydrops fetalis)
  3. Newborn can develop anemia and jaundice because the liver cannot clear the bilirubin
    - seizure and brain damage
26
Q

What can be done to prevent erythroblastosis fetalis?

A
  1. Test mothers early in pregnancy for Rh

2. If mother is Rh-, give her a rhogam

27
Q

What is a Rhogam ? when is it given?

A

anti-RhD immunoglobulin

given at 28 weeks gestation, time of delivery, or time of any trauma/bleeding

28
Q

What does the Rhogam do?

A

Masks the D antigen on fetal cells and prevents maternal sensitization

29
Q

What treatment can be given for an anemic fetus?

A

direct blood transfusion

30
Q

What is the hemoglobin level at which you would want to transfuse blood for a stable patient?

A

70-80 g/L

31
Q

When do you transfuse plasma? When do you often also need to give this to patients?

A

When people need a massive transfusion

Often also give to patients on Warfarin therapy because they lack a lot of clotting factors that are found in plasma

32
Q

What is the Buffy coat (B1) method?

A

Way of manufacturing blood products

  1. Add anticoagulant
  2. Rapid cool and centrifugation
  3. Remove plasma unit and the platelets (stay stuck on buffy coat bag)
  4. Filter out leukocytes
33
Q

Why do you need to have a leukoreduction stage?

A

because as they die, the leukocytes will burst and release their cytokine products

34
Q

How do you manufacture platelets?

A
  1. Take a plasma unit from a male donor
  2. Filter it though 4 bufy coat bags in sequence
  3. Centrifuge and extract RBCs, filter out leukocytes
35
Q

What are 7 possible transfusion reactions that can occur?

A
  1. Allergic/anaphylactic reactions
  2. Febrile or non-hemolytic from contaminating donor leukocytes and cytokines
  3. Transfusion-associated cardiac overload (TACO) from transfusing too fast
  4. Transfusion related acute lung injury (TRALI) due to antibodies to HLA
  5. Autoimmune cellular destruction
    - hemolysis (acute or delayed)
    - Neutropenia
  6. Infection
  7. Serological (anti HLA or Rh antibodies)
36
Q

What is the purpose of the diversion pouch when collecting blood?

A

to get rid of the skin plug which can have contaminating bacteria on it

37
Q

What is the most fatal transfusion reaction? Which one causes the most deaths/is more common?

A

TRALI is the most fatal

TACO causes the most deaths

38
Q

What is compatibility like for plasma transfusion? Why?

A

the opposite of what it is for blood transfusion..
ex: O can get blood from anyone but AB can only get blood from AB

B can get plasma from B or AB

A can get from A or AB

Because there will be antigens in the plasma from where you are transfusing

39
Q

Who is the universal plasma donor?

A

AB

40
Q

Can donors with anti Rh antibodies be used for donations? Which kinds?

A

they cant be used for red cells, platelets or plasma production

41
Q

For platelets, what is the compatibility testing/administration like? Why

A

Try to transfuse ABO matched platelets if available. Otherwise:

  1. Possibility of a hemolytic reaction (eg. Group A recipient receives group O platelets, group O platelets contain anti-A antibodies in plasma).
  2. Possibility of donor platelet destruction (group O recipient receives group A platelets, low levels of A antigen expressed on platelets).
42
Q

What is forward typing looking for?

A
  1. Is A or B antigen present on the patients cells

2. Is D antigen present on the patients cells

43
Q

What is reverse typing looking for?

A

If there are any anti-A or anti-B antibodies present in the patients serum

44
Q

How does forward typing work?

A

Add the patients blood and anti A, B and Rh antibodies

If there was a crossreacting Ab on the RBC, it will not pass though the gel and will therefore stay at the top

45
Q

How does reverse typing work?

A

Add the patients serum with either A or B cells

if there is agglutination, it means that they form antibodies against one or both of those blood types
- ie cant be their own

46
Q

What screening test is analogous to reverse typing

A

Indirect antiglobulin test (IAT)

47
Q

What is the purpose of the IAT test?

A

To see if the patient has antibodies against the antigens present on the allogeneic screen red blood cells

48
Q

What is done for an IAT screen?

A
  • Patient serum
  • Group O red cells of known antigenic profile
  • All clinically significant antigens have to be expressed among the screening red cells
49
Q

What is a crossmatch test?

A

like an IAT screen
• Patient serum is used
• Donor red cells are used

Gives you a either a positive or negative result

50
Q

What are the most common antigens causing delayed hemolytic transfusion reactions?

A

RHD, RHCE or Kidd

51
Q

What is the usual presentation of helayed hemolytic transfusion reactions?

A

Milder presentation of anemia and low grade fever

52
Q

What is happening during a delayed hemolytic transfusion reaction? what kind of antibody responses

A
  • Primary antibody response to a red cell alloantigen on recently transfused red blood cells.
  • Secondary antibody response to a blood group antigen that was previously encountered during pregnancy or transfusion.
53
Q

What is DAT?

A

direct antiglobulin test

54
Q

What does a DAT do?

A

checks for antibody bound to red cells in a patient

55
Q

What is the reagent for a DAT test?

A

• Poly-specific anti-human globulin reagent

- Anti-IgG and anti-C3d

Human Organs and Tissues (16 decks)

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