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Transfusion > Serology > Flashcards

Serology Flashcards

1
Q

Name three ways to enhance agglutination by IgG molecules

A
  1. Add AHG reagent
  2. Enzyme - removes proteins and acid from RBC surface therefore reducing net negative charge
  3. Reducing charge of suspending medium
    - PEG
    - Albumin
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2
Q

Haemolysis can only be detected as an endpoint when a clotted blood sample (serum) is used. Why is this?

A

Complement requires calcium.

Calcium is chelated by EDTA and citrate.

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3
Q

Why do RBCs need to be washed before grouping?

A

Most people secrete free A, B and H antigens into bodily fluids including plasma. If RBCs are not washed first, these free antigens may mop up antisera and weaken the reaction causing a grouping anomaly.

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4
Q

3 characteristics of anti-A1 antibodies

A
  1. Naturally occurring, cold reactive
  2. Produced by group A2 and A2B
  3. Not clinically significant
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5
Q

What is acquired B?

A

When a group A person acquires the B antigen ==> bacteria modify the A antigen

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6
Q

What antibody do -D- individuals make?

A

anti-Rh17

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7
Q

What antibody do Rh-null individuals make?

A

anti-Rh29

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8
Q

Do anti-S and anti-s cause haemolytic transfusion reactions?

A

Yes

anti-M and anti-N are usually cold reacting and not clinically significant but may be if reacting at 37 degrees.

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9
Q

What antigens are in the Kell system?

A

Kell (K)
cellano (k)
Kpa and Kpb
Jsa and Jsb

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10
Q

What blood is transfused in an emergency?

A

Haemolysin-free, group O negative red cells.

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11
Q

Indications for an elution

A

DAT positive RBCs:

  1. AIHA
  2. Drug-induced haemolysis
  3. HDFN
  4. Transfusion reaction investigation
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12
Q

Describe how an elution is performed

A

Acid elution (other methods = heat, chemicals)
Most important step is washing the RBCs well to ensure you are testing antibodies from the RBC, not antibodies in the plasma.
1. Wash DAT positive RBCs in PBS then in wash solution x4. Keep last wash solution (should NOT contain any antibodies)
2. Add acid
3. Add buffer
4. Get supernatant
5. Test supernatant, native plasma and LWS against antibody panel.

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13
Q

Why is EGA treatment of RBCs done?

A

Removes IgG without destroying RBC antigens ==> allows typing of DAT positive cells.

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14
Q

Indications for genotyping (4)?

A
  1. To confirm serotyping e.g. weak D testing
  2. Recent transfusion
  3. Rare phenotypes (non anti-sera available)
  4. Paternal zygosity testing
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15
Q

When is plasma reduced whole blood given to neonates? WBPR

A
  1. Exchange transfusion
  2. Large volume transfusion
    * *haematocrit is 60%
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16
Q

Name a requirement specific for donors whose components are used for neonates.

A

They must have donated (and therefore had donor screening) in the last 6 months

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17
Q

Indications for the use of irradiated blood products

A
  • Allogeneic and Autologous Bone Marrow/PBSC Transplant recipients
  • Congenital Cellular Immunodeficiency Disorders
  • Intrauterine and all subsequent transfusion and neonatal exchange transfusions
  • Hodgkin’s Disease
  • Patients receiving purine analogues with associated immunosuppression e.g. fludarabine, pentostatin, cladribine, clofarabine and bendamustine
  • Patients receiving alemtuzumab for malignant or non-malignant disorders and transplantation
  • Dedicated [directed] donations (from blood relatives)
  • HLA matched single donor platelets
  • Granulocyte transfusions
18
Q

What are neonatal platelets suspended in?

A

Plasma
PAS is not licensed for use in children <6 months old
Plasma units are single donor apheresis units

19
Q

Approach to transfusion reaction investigation (7)

A
  1. Assess patient and symptoms - important to establish etiology and severity. Fever is a key symptom.
  2. Clerical check - units, patient, request form
  3. Visual inspection - units, giving sets, pre and post-transfusion sample
  4. Serology testing - pre and post-transfusion samples (ABO and Rh group, antibody screen, DAT, IAT crossmatch)
    ==> may need to do antibody ID, eluate, antigen typing etc
  5. Microbiological testing - gram stain and culture on units, blood cultures on patient
  6. Patient testing for haemolysis - LDH, haptoglobins, bili, retics, haemoglobinuria
  7. Send haemovigilance report
20
Q

4 types of transfusion reactions

A
  1. Immunologic (acute vs delayed)
  2. Infectious (bacterial vs viral)
  3. Metabolic (citrate, K+, iron overload)
  4. Mechanical/physical e.g. air embolism, TACO
21
Q

Approach to antenatal diagnosis of HDFN

A
  1. Demonstrate maternal alloantibody that is capable of causing HDFN and work out titre
  2. Determine risk to fetus - paternal phenotyping and/or zygosity testing OR fetal DNA testing
  3. Assess whether there is fetal anaemia
    - MCA PSV
    - Invasive - only done at the time of IUTs
22
Q

Prevention of HDFN

A
  1. Anti-D immunoglobulin
    - Prophylactic (constant small volume FMH during pregnancy). 28 and 34 weeks.
    - At times of sensitising events
  2. Use of O neg blood in emergencies
  3. Give Kell negative units to women of child-bearing age/potential
  4. Screening for alloantibodies at booking and at 28 weeks
  5. Avoidance of unnecessary transfusion
23
Q

Requirements of blood for IUTs

A 
ABO and Rh matched, Kell negative, antigen negative
Hct 0.8
IAT cross match compatible
DAT negative
Leukodepleted
<5 days old
Irradiated then transfused within 24 hours
CMV negative
24
Q

Methods of determining FMH volume

A
  1. Kleihauer-Bekte - fix in methanol, acid, stain, count (pos, neg and mix controls)
  2. Flow - Anti-gamma
  3. Flow - Anti-D
25
Q

When should further anti-D be given after initial treatment?

A
  1. If fetal cells persist 48 hours after dose

2. If anti-D is not detectable by IAT

26
Q

If a mother is D negative and gives birth to a D positive baby but the Kleihauer is negative, does she still get anti-D?

A

Yes - always give 625iu IM regardless of positive or negative Kleihauer.
The Kleihauer is used to determine if ADDITIONAL doses are required.

27
Q

Considerations if the father of the baby is D negative (3)

A
  1. Ensure the father is actually the father
  2. Make sure the father does not have a weak D
  3. Confirm on 2 occasions that the father is D negative
28
Q

Prestorage leukodepletion reduces the leukocyte count to…

A

leukocytes <5 x10^6/L

29
Q

What are the benefits of adding SAG-M solution to RBCs

A
  1. Allow use of plasma and platelets
  2. Reduced viscosity
  3. Extended shelf life
    * *saline adenine glucose mannitol**
30
Q

Indications for washed RBCs

A
  1. ABO incompatible kidney transplant
  2. Recurrent FNHTRs
  3. Recurrent allergic reactions
  4. PNH (get rid of complement - but not really done unless reactions/haemolysis occurs post transfusion)
31
Q

Ways to reduce bacterial contamination in blood products

A
  1. Comprehensive donor questionnaire with experienced nurse
  2. Sterilise skin
  3. Diversion pouch
  4. 2 hours stand down period
  5. Closed system, sterile docking
  6. Storage - monitoring of temperature, shelf life limits
  7. BacT alert system, serological and PCR/NAT testing for infections
  8. Traceability
  9. Haemovigilance to reduce further episodes
32
Q

Why are blood products irradiated?

A

To prevent TA-GVHD

33
Q

Indications for irradiated blood products

A
  1. Severe congenital immunodeficiencies
  2. Hodgkin lymphoma
  3. All bone marrow transplants
  4. Purine analogues
  5. Alemtuzumab
  6. IUTs
  7. Exchange transfusion
  8. Directed donations
  9. HLA-matched platelets
  10. Granulocyte transfusions
34
Q

Shelf life of irradiated red cells

A

14 days after irradiation except for IUTs ==> use within 24 hours

35
Q

Quality control for FFP

A

Check that the factor levels are >70% of fresh plasma value.

36
Q

What method is used for fractionation at CSL Behring

A

Ion exchange chromatography

- proteins come off charged column into fluid based on their charge

37
Q

Name 4 pathogen inactivation steps used in fractionation

A
  1. Dry heat
  2. Low pH
  3. Viral filtering
  4. Solvent detergent
38
Q

Haemolysin testing

A

Clotted donor tube + AB cells + complement
manually observe for haemolysis
Controls - Anti-A for positive, AB serum for negative

39
Q

Complications of PLEX

A
  1. Haemodynamic including vasovagal
  2. Citrate toxicity
  3. Allergic reactions
  4. Dilutional coagulopathy
40
Q

Donor requirements for granulocyte transfusions

A 
(Given G-CSF and steroids)
ABO and Rh matched
HLA matched
CMV negative
Avoid family members if a sibling allo SCT will be performed

Transfusion (3 decks)

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