Transfusion Immunology

Question 1

what are the 3 basic concepts involved in blood groups and transfusion reactions?

Answer 1

1- self and foreigness
2- T dependency and independency
3- genetic polymorphism and inheritance

Question 2

blood cell antigens are what kind of antigens?

Answer 2

alloantigens

Question 3

what determines the chemical composition of blood cell antigens?

Answer 3

polysaccharide determined by glycosyl transferases

Question 4

what are the mechanisms of inheritance of blood cell antigens?

Answer 4

…

Question 5

what are the mechanisms of expression of blood cell antigens?

Answer 5

dominant or codominant

Question 6

what gene codes for the backbone in the sugar moiety?

Answer 6

H gene

Question 7

what does the H gene encode?

Answer 7

a fucosyltransferase which encodes the O antigen base structure

Question 8

the H gene is absent in which form of leukocyte deficiency?

Answer 8

Bombay blood group phenotype

Question 9

sugar for A allele

Answer 9

N-acetylgalactosamine glycosyl transferase

Question 10

sugar for B allele

Answer 10

galactosyl transferase

Question 11

the carbohydrate structure is recognized by which cells?

Answer 11

B cells (found only in individuals not expressing the phenotype)

Question 12

Natural antibodies or isohemagglutinin immune responses against the shared bacterial antigens are dependent on which cells?

Answer 12

T cells

Question 13

Is the H allele recessive or dominant?

Answer 13

recessive
- it is considered recessive because individuals develop antibodies against the missing blood group antigen around the 3-6th month of life

Question 14

Anti-A and Anti-B antibodies represent what class?

Answer 14

IgM

Question 15

what are the other blood groups?

Answer 15

secretor
Lewis
MNSs
Kell
Duffy

Question 16

secretor

Answer 16

most of us encode a gene which allows the A,B and H antigens to be secreted

Question 17

Lewis

Answer 17

LeA and LeB are not ABO linked by are structurally related; natural antibodies in Le- individuals

Question 18

MNSs

Answer 18

• MN group located on glycophorin A

- Ss group on glycophorin B

Question 19

Kell

Answer 19

• K and k allelic forms; K is the stronger antigen

- protein antigen may provoke strong transfusion reaction and HDN

Question 20

Duffy

Answer 20

Duffy antigen receptor for chemokines (DARC)

• FyA or FyB - an important receptor on RBCs for the malarial parasite Plasmodium vivax; also binds various chemokines
• Fy- or Duffy null - 60% African or of African descent

Question 21

the Rh system has how many different antigens?

Answer 21

44

Question 22

which of the 6 alleles of the Rho system is clinically the most important because of its high immunogeneicity?

Answer 22

D

Question 23

when does Rh appear in a human?

Answer 23

early fetal development

Question 24

induced antibodies in Rh- person can be found following which events?

Answer 24

• mis-matched transfusion
• pregnancy
• abortion

Question 25

transfusion reactions occur due to reactivity btw _____ antibodies and _____ red blood cells

Answer 25

recipient | donor

Question 26

what hemolytic symptoms occur after an incompatibility rxn?

Answer 26

``` diffuse muscular pain headache vomiting rise in temperature shock renal failure ```

Question 27

what is the primary means by which HDN occurs?

Answer 27

Rh- mother has a Rh+ baby

Question 28

what is the second most common HDN blood group?

Answer 28

Kell

Question 29

under what condition would HDN happen to the first baby?

Answer 29

1- if mother had previously received mismatched transfusion | 2- mother had a previous miscarriage or abortion of an Rh+ baby

Question 30

in HDN mother becomes _____ with baby's cells when they enter ______during first pregnancy; this number is ususally too low to induce problems for that baby

Answer 30

sensitized | circulation

Question 31

What are the steps for HDN that begin with a mother is pregnant with her first Rh+ fetus?

Answer 31

1- sensitization of mother 2- during delivery, Rh+ from cord blood mix with mom's blood 3- mother becomes immunized producing anti Rh+ IgG 4- IgG can cross placenta and damage subsequent Rh+ fetus

Question 32

___ incompatibility MAY diminish the possibilities of HDN

Answer 32

AB; Normally occurring anti-A and anti-B blood groups in the mother may clear antigenic Rh+ fetal RBCs and prevent sensitization

Question 33

approximately what percent of cases are due to ABO incompatibility?

Answer 33

50-60%; | Cases are usu minor with transient anemia and jaundice with slightly elevated bilirubin

Question 34

Direct Coombs testing purpose

Answer 34

detects presence of antibodies on RBCs

Question 35

INdirect Coombs testing

Answer 35

detects presence of antibodies against RBC antigens

Question 36

cross matching

Answer 36

matches rbc of donor against serum of recipient to avoid reaction against other antigens (indirect coomb's)

Question 37

practice coombs

Answer 37

...