Lecture 19 + 20 - blood groups

Question 1

what are surface antigens composed of

Answer 1

glycoproteins
glycolipids

Question 2

what chromosome are genes encoding ABO antigens on

Answer 2

chromosome 9

Question 3

what do ABO genesdo

Answer 3

• produce glycotransferases
• add sugars to H substance (by making the enzymes that are responsible for adding it)

Question 4

what does O gene add to H substance

Answer 4

no effect

Question 5

what does group A gene add to H substance

Answer 5

N-acetyl galactosamine (GlcNAc)

Question 6

what does group B add to H substance

Answer 6

D-galactose (Gal)

Question 7

what is the cause of productions of antibodies

Answer 7

produced in response to the environemnt
as many things in nature have similar complexes to RBC sugars = elicit production of antibodies

Question 8

what antibodies does AB type have

Answer 8

none

Question 9

what antibodies does O type have

Answer 9

anti A and anti B

Question 10

subtypes of type A and their prevelance

Answer 10

A1 = 80%
A2 = 20%

Question 11

when might subtypes create an issue for transfusion

Answer 11

repeated transfusions can cause a reaction

Question 12

what is the Bombay phenotype

Answer 12

• cant form 2-L-fucosyltransferase necassary for H substance formation
• so NO h substance
• and so present as O type
• but they have antibodies to A, B (like O) and H substance
• but when transfused with O = agglutinates
• can only have blood from eah other

Question 13

all the antigens of Rh blood group system

Answer 13

C
c
D (biggest clinical influence)
E
e

Question 14

what are the genes for the Rh blood system

Answer 14

RhD = codes proteins with D antigen
and RhCE = codes for RhCE protein with C, c, E and e antigens

Question 15

RHD gene

Answer 15

on chromosome 1
is dominant
if you inherit even one Rh+ then you are positive

its either present or not

Question 16

RHCE gene

Answer 16

can have 4 variations

Question 17

what is R0 blood type

Answer 17

someone with R0 is always +ve, and has Dce
so always have the D gene

Question 18

what happens when someone has medical conditions that require mutiple blood transfusions

Answer 18

need more extensively matched blood
so instead of just matching ABO and Rh +ve or -ve
they need to match the subtype also
e.g. R0 matching

Question 19

which group are more donors needed

Answer 19

R0 subtype rare
and is 10x more common in Black african/black carribean backgrounds
so there’s a push for them to donate more

and theyre also at more risk of SCD, which need regular transfusions

Question 21

in a Rh -ve mum and Rh +ve baby, what happens if the blood mixes and explain HDN

Answer 21

when blood mixes
mum’s immune system mounts a response against the Rh+ve antigens

But usually at delivery there’s no time for them to react ie an immune response to take place (usually takes 72hrs)
But the antibodies remain in the blood

So in first pregnancy theres no impact

BUT

In second, antibodies are already there

in second, when blood mixes, it can cause immune response and causes haemolytic disease of newborn

Question 22

what can women be given for haemolytic disease of newborn

Answer 22

if baby is Rh +ve = anti d immunoglobulin is given

= destroys the foetus’ Rh +ve D cells before they can cause the mum to produce her own anti D

Question 23

how might ABO haemolytic disease of newborn occur

Answer 23

happens to group A or B babies born to group O mothers (they have anti A and anti B antibodies)

Question 24

how is blood group O associated with blood clotting

Answer 24

usually blood groups dont have any link with helath conditions
but blood group O will have 25% less efficient factor 8 and vWF

Question 25

def of blood transfusion

Answer 25

transfer of blood or blood based products from one person into the circulation of another

Question 26

what do the plastic bags contain

Answer 26

anticoagulant

Question 27

process of blood transfusion from donor to patient

Answer 27

donor blood screened
components seperated from whole blood
goes to hospital blood bank
then to ward
then to patient

Question 28

what is whole blood seperated into

Answer 28

cellular components ie red cells, platelets, white cells
and
fresh plasma

Question 29

how much is one unit of red cells blood

Answer 29

280ml
(leucodepleted)

Question 30

how much does each unit of red cells increase the Hb

Answer 30

10g/L

Question 31

how long does red cell transfusion take

Answer 31

2-4 hrs

Question 32

what temp is red cell blood stored

Answer 32

4 deg celcius

Question 33

what is shelf life of red cells

Answer 33

up to 35 days
(the older the blood, the more affinity of O2 it has)

Question 34

what is the universal donor

Answer 34

O neg

Question 35

universal recipient?

Answer 35

AB +ve

Question 36

how much is one unit of fresh frozen plasma (FFP)

Answer 36

200-250ml

Question 37

temp. of FFP

Answer 37

-30 deg cel

Question 38

what does FFP contain

Answer 38

all coagulation factors
is group specific

Question 39

shelf life of FFP

Answer 39

36 months when frozen
and 24hrs after thawing

Question 40

how much is one adult dose of platelets taken from

Answer 40

4 different platelet donations
(isnt group specific)

Question 41

what does ABO forward group test for

Answer 41

adding red cells to first 4 columns
tests for antigens on the cell surface (A, B and D antigens)

Question 42

what does ABO reverse group test for

Answer 42

adding plasma to last 2 columns
checks for antibodies in the plasma

Question 43

what is a crossmatch

Answer 43

patient plasma mixed with donor’s red cells to ensure compatibility