blood groups

what are the 2 main blood grouping systems?

- ABO

- Rhesus

what are the 4 different groups in the ABO grouping system?

- A

- B

- AB

- O

what are the 2 antigens of the ABO grouping system?

- A antigens

- B antigens

what antigens does type A have?

A antigens only

what antigens does type B have?

B antigens only

what antigens does type AB have?

A and B antigens

what antigens does type O have?

neither A or B antigens

what else contributes to the ABO grouping system?

antibodies:

- anti-A antibodies

- anti-B antibodies

what type of antibodies are anti-A and anti-B antibodies?

IgM

what antibodies does type A have?

anti-B antibodies

what antibodies does type B have?

anti-A antibodies

what antibodies does type AB have?

neither antibody

what antibodies does type O have?

both anti-A and anti-B antibodies

which blood type is the universal donor and why?

type O because it has no antigens on the surface that could interfere with other antibodies

which blood type is the universal receiver and why?

type AB because it does not contain any anti-A or anti-B antibodies that could interfere with antigens

how many different Rhesus (Rh) antigens are there?

5 clinically significant ones

what are the 5 clinically significant antigens?

- D

- C

- c

- E

- e

which is the main Rh antigen we focus on and why?

- Rh D

- because is it the most immunogenic, causes the greatest immune response

- most likely to cause a transfusion reaction

how do we determine whether someone is Rhesus positive or negative?

depends on whether they have Rh D antigen on surface of erythrocytes

when would someone be Rhesus positive?

if they have Rh D antigens

when would someone be Rhesus negative?

if they lack Rh D antigens

which blood can Rh+ people receive?

Rh+ and Rh-

which blood can Rh- people receive?

Rh- only

do all Rh- people have anti-D antibodies?

no, only when they have been exposed to Rh+ erythrocytes

when can the Rhesus grouping system cause problems in pregnancy?

if mother is Rh- and foetus is Rh+

what happens if foetus is Rh+ and mother is Rh-?

- presence of Rh D antigens stimulates production of anti-D antibodies

- maternal anti-D antibodies recognise and destroy foetal Rh D antigens - haemolysis

what is this called?

haemolytic disease of the new-born (HDN)

why is it not a large problem in nulliparous mothers?

the anti-D antibodies are mostly IgM which cannot cross the placenta

how do we prevent haemolytic disease of the new-born (HDN)?

administration of anti-D Ig prophylaxis

why is the Rhesus factor grouping system a large problem in multiparous mothers?

IgG anti-D anitbodies will be produced, which can cross the placenta

how does anti-D Ig prophylaxis work?

destroys feotal RBCs that leak into maternal circulation