WEEK 3: ABO Blood Groups

Question 1

what is a blood group?

Answer 1

An inherited character of the red cell surface detected by a specific alloantibody

Question 2

what is the biological role of a blood group? (4)

Answer 2

–Recognition of self and non-self
–Maintenance of cellular integrity
–Involvement in cell maturation
–Susceptibility or resistance to disease

Question 3

which two classes of immunoglobulin are of interest in blood groups for transfusion?

Answer 3

IgM and IgG

Question 4

what is the structure of IgM?

Answer 4

pentameric - means 5 sub units. It is a big molecule

Question 5

how many antigen binding sites does IgM have?

Answer 5

10

Question 6

why do rbcs repel each other?

Answer 6

the membrane has a negative charge

Question 7

do IgM anti bodies cross the placenta?

Answer 7

no.

Question 8

what temp does IgM work best?

Answer 8

below 37 celcius

Question 9

what is the structure of IgG?

Answer 9

monomeric (a protein that has a single polypeptide chain)

Question 10

how many antigen binding sites does IgG have?

Answer 10

2

Question 11

Which antibody causes agglutination? IgM or IgG?

Answer 11

IgM

Question 12

can IgG cross placenta?

Answer 12

yes.

Question 13

why doesn’t IgG not usually bind complement?

Answer 13

there’s not enough to activate cascade

Question 14

what percentage of people in the UK have the blood group O?

Answer 14

47%

Question 15

what percentage of people in the UK have the blood group A?

Answer 15

42%

Question 16

what percentage of people in the UK have the blood group B?

Answer 16

8%

Question 17

what percentage of people in the UK have the blood group AB?

Answer 17

3%

Question 18

what 3 genes governs the presence of A and B blood groups?

Answer 18

H gene, A gene and B gene

Question 19

what chromosomes are H, A and B genes located on?

Answer 19

H is on chromosome 19. A and B are both located on chromosome 9 and are co-dominant alleles.

Question 20

what enzyme does the H gene code for?

Answer 20

H enzyme

Question 21

what enzyme does the B gene code for?

Answer 21

B enzyme

Question 22

slide 15

Question 23

what genotypes produce blood group A? (2)

Answer 23

AA and AO

Question 24

what genotypes produce blood group B? (2)

Answer 24

BB and BO

Question 25

what genotype produces blood group AB?

Answer 25

AB

Question 26

what genotype produces blood group O?

Answer 26

OO

Question 27

what percentage is there of each subgroup of A antigen?

Answer 27

*A1 –80% *A2 –20%

Question 28

when do antibodies develop?

Answer 28

over the first 4 months after birth

Question 29

are ABO antigens sugars or proteins?

Answer 29

sugars

Question 30

what is Landsteiner's Law?

Answer 30

ABO antibodies are found in the plasma against the ABO antigens an individual lacks

Question 31

give the antigen on rbc and antibody in plasma if patient has blood group O.

Answer 31

antigen on rbc - none antibody in plasma - anti-A and anti-B

Question 32

give the antigen on rbc and antibody in plasma if patient has blood group A

Answer 32

antigen on rbc - A antibody in plasma - anti-B

Question 33

give the antigen on rbc and antibody in plasma if patient has blood group B

Answer 33

antigen on rbc - B antibody in plasma - anti-A

Question 34

give the antigen on rbc and antibody in plasma if patient has blood group AB

Answer 34

antigen on rbc - A and B antibody in plasma - none

Question 35

when do antigens develop?

Answer 35

development over first 1-2 years of life

Question 36

what gene allows the RhD antigen to be incorporated into the cell?

Answer 36

RhAG gene on chromosome 6

Question 37

what are the characteristics of weak D?

Answer 37

- possesses all normal D antigens but has less - cannot produce anti-D

Question 38

what are the characteristics of partial D?

Answer 38

- lacks part of a normal D antigen - can produce anti-D - regarded as RhD neg as a donor

Question 39

what do RhD negative individuals lack?

Answer 39

they lack the D antigen (no RhD gene)