Lecture 1 - Blood Groups

Question 1

what are blood group systems considered as?

Answer 1

antigens on membranes of cells

Question 2

how are red cells agglutinated?

Answer 2

when they are joined together by cross linking of antibodies

Question 3

what blood group is the most clinically significant?

Answer 3

ABO

Question 4

what is landsteiners law?

Answer 4

that antibodies in plasma match with antigens that are not on the surface of the red cells

Question 5

what is the cause of almost all serious transfusion reactions?

Answer 5

ABO incompatability

Question 6

what is the difference between the A and B antigens?

Answer 6

different terminal carbohydrates to the H antigen

Question 7

how is a H antigen made?

Answer 7

H allele produces H transferase which converts a precursor substance to a H antigen

Question 8

what converts a H antigen to an A or B antigen?

Answer 8

A or B transferase

Question 9

what does A transferase add to the H antigen?

Answer 9

N-acetyl-D-galactosamine

Question 10

what does B transferase add to the H antigen?

Answer 10

D-galactose

Question 11

what is the features of the transferase of OO genotype?

Answer 11

no functional transferase so H left unchanged

Question 12

what is the name for the carbohydrate chains added to a H antigen?

Answer 12

immunodominant sugars

Question 13

what is the H immunodominant sugar?

Answer 13

Fuc

Question 14

what is the A immunodominant sugar?

Answer 14

GalNAc

Question 15

what is the B immunodominant sugar?

Answer 15

Gal

Question 16

how is blood grouping linked to natural selection?

Answer 16

certain blood groups cause susceptibility with certain diseases

Question 17

what antibodies are in the plasma of a type A patient?

Answer 17

anti-B

Question 18

what antibodies are present in the plasma of a type B patient?

Answer 18

anti-A

Question 19

what antibodies does an AB patient have?

Answer 19

none, yet A and B antigens

Question 20

what antibodies does a O patient have?

Answer 20

anti-A and anti-B yet no antigens on red blood cell

Question 21

what antibodies can cause intravascular lysis and how?

Answer 21

anti A and B and anti A,B by activating the complement pathway

Question 22

what group is the universal red cell donor and why?

Answer 22

O as no antibodies on the surface

Question 23

what group is the universal red cell recipient and why?

Answer 23

AB as they have no antibodies in the plasma

Question 24

what group is the universal plasma donor?

Answer 24

AB as will not give patient any antibodies

Question 25

what group is the universal plasma recipient?

Answer 25

group O as no antigens to reject the antibodies in the plasma

Question 26

what is HDFN?

Answer 26

haemolytic disease of the foetus and newborn

Question 27

how is blood grouping carried out in present years?

Answer 27

antiserum is contained in a gel matrix and the blood is passed through, if the blood cells contain the matching antigen they are trapped in the matrix

Question 28

what are the blood subgroups?

Answer 28

A1, A2, A3 and Ax

Question 29

how does a subgroup form?

Answer 29

there is a quantitative reduction in the number of A antigens on the surface of red cells

Question 30

how can you tell that there is a subgroup?

Answer 30

if there is a slight positive reaction to the A antibody

Question 31

what is anti-A1?

Answer 31

this is the formation of ability to produce anti-A1

Question 32

what is an acquired B blood type?

Answer 32

group A patients who produce a B like antigen so therefore start grouping as a B

Question 33

what diseases is acquired B linked to?

Answer 33

GI bacterial diseases and colon cancer patients due to the action of bacterial enzymes

Question 34

how is acquired B caused?

Answer 34

bacterial enzymes nibble off the end of the carbohydrate chain, transforming it into a B chain

Question 35

how is loss of ABO antigens caused?

Answer 35

due to malignancy

Question 36

what disease causes loss of ABO antigens?

Answer 36

usually myeloid leukaemia

Question 37

what does loss of ABO antigens indicate is changing?

Answer 37

genetic changes in the stem cell line at the ABO gene level

Question 38

how is loss of ABO antigens detected?

Answer 38

flow cytometry which marks the different antigens showing different populations

Question 39

what is an Oh blood group?

Answer 39

Hh group people cannot make H, A or B antigens as no H antigen produced

Question 40

what grouping features does an Oh group have?

Answer 40

may be genetically A or B but groups as an O

Question 41

what blood does group Oh react with?

Answer 41

have strong anti H antibodies so will react with all blood except its own

Question 42

what is the second most important blood group?

Answer 42

Rh

Question 43

what are the 5 antigens belonging to Rh?

Answer 43

D, C, c, E and e

Question 44

what antigens does D produce?

Answer 44

D antigens

Question 45

what antigens does the CE gene produce?

Answer 45

ce, Ce, cE or CE

Question 46

why is the D antigen the most important?

Answer 46

most immunogenic

Question 47

why is the D antigen the most immunogenic?

Answer 47

large membrane protein so even small amount of exposure with RhD positive blood if patient is negative still causes production of anti-D antibodies

Question 48

what does it mean if you are rhesus positive?

Answer 48

have the D gene

Question 49

what is weak D?

Answer 49

quantitative difference in number of antigen sites on the red blood cell, do not form anti-D antigens

Question 50

how is weak D caused?

Answer 50

mutation of interior of D molecule, causing less D antigens on the surface

Question 51

is weak D still R+?

Answer 51

yes but have a weak positive reaction to the antiserum

Question 52

what is partial D?

Answer 52

qualitative difference in the antigen, can still form anti-D with the missing parts of the antigen

Question 53

how is partial D formed?

Answer 53

mutation on the outside of the D molecule

Question 54

are partial D patients still R+?

Answer 54

as a donor yes, as they do still have part of the molecule, yet not as a recipient in case they may form anti-D antibodies with the blood they receive