Transfusion Medicine DSA

Question 1

seen after the first immune exposure to a “foreign” protein Ag
- noticed days or weeks after such exposure

Answer 1

primary response

- sustained high concentration of IgM with some formation of IgG

Question 2

seen upon a repeat exposure to a “foreign” protein Ag

- noticed much quicker after such exposure

Answer 2

secondary (anamnestic) response

- transient rise in IgM and sustained IgG increase

Question 3

H Ag only

Answer 3

O blood type

Question 4

H + A

Answer 4

A blood type

Question 5

H + B

Answer 5

B blood type

Question 6

H + (A+B)

Answer 6

AB blood type

Question 7

someone capable of making ABO antigens in their secretions and plasma
- roughly 80% of the population carries at least 1 allele

Answer 7

secretor

• allele is called “se”
• encodes an enzyme that allows individual to make the H antigen on long carbohydrate-rich chains (type 1 chains)
• once the H Ag is made, the person can make either A or B antigens

Question 8

which subtype of blood A and AB are the most common?

Answer 8

A1, A1B

- both 80%

Question 9

how can disease alter expression of ABO Ag

Answer 9

• leukemia: decreases Ag
• “acquired B”: intestinal obstruction -> increase in bowel permeability, bacterial polysaccharides into circulation absorbed by group A cells
• gastric or pancreatic carcinoma: serum contains excessive blood group specific soluble substances (BGSS) which neutralize antisera used in forwarding group

Question 10

which phenotype has the absence of H?

Answer 10

bombay phenotype (Oh)

• RBC has NO Ag
• contains anti-A, anti-B, anti-AB, anti-H
• anti-H IgM binds complement & lyses cells
• can only receive Bombay blood

Question 11

D antigen

Answer 11

Rhesus factor

Question 12

d antigen

Answer 12

absence of D

Question 13

strong D expression

- genotype DD or Dd

Answer 13

Rh positive

Question 14

weak D expression

• genotype Dd
• phenotype weak D

Answer 14

Rh positive

Question 15

no D expression

• genotype dd
• phenotype d

Answer 15

Rh neg

- do not want recipient to develop anti-D, so only give Rh negative blood

Question 16

when is Rhogam contraindicated?

Answer 16

in Rh-positive individuals

• products made from human blood
• after administration, transitory increase in antibodies will yield positive serological testing

Question 17

ranked second in immunogenicity after D

• well developed at birth
• alloantibodies to K are common (IgG & rxn at 37C)

Answer 17

Kell system

• K = Kell
• k = cellano

Question 18

Jk(a) and Jk(b)

- both anti-Jk(a) and anti-Jk(b) are seen commonly

Answer 18

Kidds system

- Ab’s can “disappear” -> no Ab detected during initial Ab screen and crossmatch

Question 19

what does Martin mean by “treacherous Kidds”?

Answer 19

3/4 will exhibit delayed hemolytic transfusion reactions

- activated complement -> rapid hemolysis d/t synergistic activation of complement and cell-bound Ab

Question 20

Fy(a) and Fy(b)

Answer 20

Duffy system

- IgG associated with HDN and hemolytic transfusion reaction

Question 21

what are the Duffy genotypes seen in caucasians?

Answer 21

Fy(a+,b+) or Fy(a+, b-) or Fy(a-,b+)

Question 22

what are the Duffy genotypes among African Americans?

Answer 22

many Fy(a-,b-) -> this genotype is resistant to plasmodium vivax infection!!

Question 23

several antigens, most important

• M & N
• S & s

Answer 23

MNS system

• anti-M usually IgM, occasionally IgG
• dosage effect: react more strongly with homozygous cell than heterozygous cell

Question 24

usually IgM “warm” Bas, naturally occurring

Answer 24

Lewis system

• Le Ag found in secretions & plasma, then Ag absorbed onto RBC membrane
• need secretor & Hh genes