12-05 L2 Transfusion medicine

Question 1

ABO blood groups

• mode of inhertiance
• chromosome

Answer 1

• autosomal co-dominant inheritance
• Chromosome 9

Question 2

ABO blood groups enzymes

• Gp A
• Gp B

Answer 2

• Gp A: N-acetylgalactosaminyltransferaase
• GpB: Galactosyltransferase

Question 3

What antigen are the sugar molecules added on in RBCs?

Answer 3

• H antigen is the precursor substance

Question 4

What percentage of people have A and B antigen present as a soluble materail in their plasma?

Answer 4

80%

Question 5

ABO antibodies

• IgM
• IgG

Answer 5

• IgM: most of them are
• IgG: problem if baby in mother wombs has different blood type,
  
  • mom antibodies start to attack baby

Question 6

ABO typing

• Forward typing
• Back typing

Answer 6

• Forward typing: look at the proteins on the RBCs
• Back(reverse) typing: looking at the serum of the pt and deciding what they have
  
  • i.e. plasma anti-A pt has B

Question 7

Group AB (antibodies present in the serum)

Group o (antigens present on RBCS)

Answer 7

• Group AB: no antibodies present in plasma,
  
  • thus it makes them the ideal plasma donor
• Group O: no antigens present on RBCs
  
  • makes them ideal blood donor

Question 8

Rh freq

Answer 8

• rh + (85%): express D antigen (+)
• rh- (15%): no D antigen on red cell

Question 9

What is the most immunogenic of all antigens?

Answer 9

D- antigen

Question 10

Rhesus (Rh) blood groups

• inheritance
• chromosome
• what is unique about their polypeptides

Answer 10

• inheritance: autsomal co-dominant inheritance
• Chromosome 1
• polypeptides are produced unglycosylated

Question 11

What is the Mechanism of immune injury associated with transfusion call

Answer 11

• Type II hypersensitivity rxn
• Red cell destruciton

Question 12

Type II hypersensitivity

what is the difference b/t Opsonization & direct lysis

Answer 12

• Opsonization
  
  • indirect killing of the cell (help from macrophage)
• Direct lysis
  
  • antibody reaches with the cell and cell lysis occurs ‘intravascular hemolysis’

Question 13

What is the 2nd and 3rd most commone cause of transfusion-related death?

Answer 13

• incompatible transfusion
  
  • result of patient misidentifitcaiton at sample collection, transfusion or error in lab

Question 14

Describe the following tests:

• DAT (+ and -)
• Elution test

Answer 14

• DAT +: agglutination, antibody on cells in vivo
• DAT -: no agglutination, no antibody on cells
• Elution test: follow up to DAT +
  
  • removes antibody from red cell surface
  • id antibody present in eluate

Question 15

describe the following test:

Compatibility test

Answer 15

• antibody binds to cells (agglutination) incompatible
• antibody doesnot bind to cells (no agglutination) compatible

Question 16

difference b/t acute anemia and chronic anemia

Answer 16

• acute anemia
  
  • >25-40% give them RBC transfusion,
  • <25% no RBC transfusion if previously healthy
• Chronic anemai
  
  • treat pathology
  • i.e give them iron, folate, B12

Question 17

Platelat Transfusion

indication of thrombocytopathy due to what 3 things?

Answer 17

• Medications
  
  • ASA, Plavix (clopidogrel)
• Clincial conditions
  
  • Uremia
• Mechanical trauma
  
  • Cardiopulmonary bypass with excessive bleeding

Question 18

Cryoprecipitate

indications

Answer 18

• Fibrinogen def (DIC, dilutional coagulopathy)
• Factor 8 def.

Question 19

Fresh frozen plasma

• whats in it
• indications

Answer 19

• contains all coagulation factors
• Indications:
  
  • Liver failure, dilutional coagulopathy, DIC
  • reverse warfarin
  • replacement solution
    
    • plasma exchance (TTP)

Question 20

Washed components

Platelets and RBC

• What is it
• indicaitons

Answer 20

• remove most of the plasma
• indicaitons
  
  • prevent febrile non-hemolytic tx rxn
  • prevent urticarial allergic rxn
  • prevent anti-IgA anaphylaxis