Blood groups and transfusions Flashcards
(46 cards)
where are the blood groups located on the red cell
Located on the surface of the red cell
what blood group system do sugar residues form
what blood group system to proteins for
Sugar residues form one type of blood group system e.g. ABO - ABO polysaccharide antigens
Proteins form another type of blood group system e.g. Rhesus (Rh)
what determines the blood group
Genes determine what particular sugar or protein is produced and thus the blood group
what are antibodies
- Antibodies are immunoglobulins in plasma which react specifically with their antigens e.g. the anti-A antibody reacts with the A antigen
what are autoantibodies
- Can have autoantibodies – react with antigens present on the persons own red cells
what are alloantibodies
produced by person against antigens not present on persons own red cells
what are the two types of alloantibodies
naturally occurring (exposure to environment)
immune (contact with antigen)
what is agglutination
antibody binds to antigen and clumps stuff together
what antigens are in the ABO system
- A and B polysaccharide antigens
what are the naturally occurring antibodies against the ABO system
- Anti-a
- Anti-b
what are the immune antibodies agains the ABO system
IgM
IgG
what does IgM do
- Cold-acting (bind at room temperature)
- Activate complement
what happens if there is an ABO mismatch transfusion
ABO antibodies can be IgG or IgM, if there is an ABO mismatch transfusion and this will activate haemolysis of red blood cells,
name the blood groups and what antibody they have in there plasma
A (has anti-B in plasma)
B (has anti-A in plasma)
O (has anti-A and anti-B in plasma)
AB (has no ABO antibody in plasma
what will the ABO blood groups be agglutinated by
- Blood of group A will be agglutinated by anti-A
- Blood group B will be agglutinated by anti B
- Blood of group AB will be agglutinated by anti-A and anti-B
- Blood group O will not be agglutinated by anti-a or anti-b
name the phenotypes of the blood groups and what there genotypes could be
A - AA or AO
B - BB or BO
AB - AB
O - OO
for each blood group name
- blood group repent
- antigen present
- antibodies present
- can receive blood groups
Blood group A
- antigen present = A
- antibodies present = B
- can receive blood groups = A and O
Blood group B
- antigen present = B
- antibodies present = A
- can receive blood groups = B and O
Blood group AB
- antigen present = AB
- antibodies present = None
- can receive blood groups = A or B or O
Blood group O
- antigen present = H
- antibodies present = A and B
- can receive blood groups = O
describe the rhesus blood group system
3 pairs of proteins, inherited as triplet:
D or no D (written as d)
C or c
E or e
what can antibodies against rhesus blood groups form
Can form only following exposure:
Transfusion
Pregnancy
Transplantation
describe Rh genotype and phenotype
- Genes are in triplets
- Depending on the phenotype you can try and predict the genotype
- Inherit one triplet from each parent
- Alleles are co-dominant
how can phenotype and genotype of rhesus groups be determined
- Phenotype can be determined serologically
- CcDE red cells will agglutinate with anti-C, anti-c, anti-D, antiE, but not anti-e
genotype can be determined by molecular techniques
if you are RhD positive what blood can you get
if you are RhD negative what blood can you get
RhD positive = RhD positive or RhD negatie
RhD negative = only RhD negative
what happens if you are given the wrong RhD positive or RhD negative in a blood transfusion
- can lead of haemolytic disease of the foetus and newborn
- this is because the mother can form RhD antibodies which cause haemolysis
- leads to fatal anaemia and neonatal jaundice which can cause brain damage
how do you prevent haemolytic disease of the foetus
Prophylaxis after a sensitising event during pregnancy Prophylactic anti-D Ig all D negative mothers in third trimester
Postnatally if baby D positive
Free fetal DNA testing for RHD typing of of fortus from maternal sample now available to help targeted Anti D prophylaxis