Blood Groups and Blood Transfusion Flashcards
How many blood groups are there?
- 4
What are the 4 main blood groups (we need to know), without accounting for the rhesus antigen?
- A - B - AB - O
Self antigens are what is present on all human cells to ensure the body does not attack itself (hypersensitivity type II). What antigens are present on the surface of RBCs on in each blood type?
- A = A antigen
- B = B antigens
- AB = A and B antigens
- O = no antigens
Self antigens are what is present on all human cells to ensure the body does not attack itself (hypersensitivity type II). If incorrect blood is transfused what, causing a type II hypersensitivity, what anti-bodies in the blood of each blood type are present to facilitate this immune response?
- A = anti B antibodies
- B = anti A antibodies
- AB = none
- O = anti A and B antibodies
Why would an individual with blood type A have anti B antibodies in plasma?
- because B antibodies would be recognised as foreign
- the body would then attack blood with B antigens
What are the 3 main components of blood antigens?
1 - fucose (sugar)
2 - galactose (sugar)
3 - N-acetylgalactosamine (sugar)
What is the ABO blood group system?
- blood group system including A, B, AB or O
- most clinically relevent
What is the Rh blood group system?
- blood group indicating if patient has rhesus antigen
- can include + (with antigen) or - (without antigen)
What is the H substance, also referred to as antigen H?
- precursor for A and B antigens on blood
What is the H substance, also referred to as antigen H composed of?
- fucose attached to an oligosaccharide
How is the H substance, also referred to as antigen H made on the red blood cell?
- immature RBCs have nucleus and chromosomes
- chromosome 19 expresses fucose transferase
What enzyme is expressed on chromosome 19 that adds fucose to the oligosaccharide creating the H substance, also referred to as antigen H?
- fucose transferase
How does blood type A and B add to the H substance, also commonly known as H antigen to become A and B blood type?
- locus on chromosome 9 expresses an enzyme
In order for blood type A to form antigens it needs to add to the H substance, also commonly known as H antigen. It does this by adding to the fucose (H substance), what enzyme is expressed on chromosome 9 to facilitate this, and what is added to the fucose?
- N-acetylgalactosamine transferase
- adds acetylgalactosamine to fucose
What is common in the structure of all blood type antibodies?
- all begin as H substance (H antigen)
- all attached to RBCs by glycoprotein
- galactose attached glycoprotein
What is the structure of the A antigen present in blood group A patients?
- glycoprotein attached to RBC
- galactose
- fucose
- acetylgalactosamine
In order for blood type B to form antigens it needs to add to the H substance, also commonly known as H antigen. It does this by adding to the fucose (H substance), what enzyme is expressed on chromosome 9 to facilitate this, and what is added to the fucose?
- glycosyl-transferase
- adds galactose to fucose
What is the structure of the B antigen present in blood group B patients?
- glycoprotein attached to RBC
- galactose
- fucose
- galactose
How is chromosome 9 able to expresses for A, B or O antigens in the same person?
- each person has 2 copies of chromosome 9
- each person has gene allele for A, B or O
In patients with blood types A and B, would the gene expression on the allele on chromosome 9 be expressing A, B or O antigens from both mum and dads copy of the chromosomes?
- blood type A = A + O
- blood type B = B + O
- blood type AB = A + B
- blood type O = O + O
- the O is generally silent unless both parents have it
What are agglutinins?
- IgM antibodies
- IgM = pentameric
- pentameric = 5 subunits for binding
What is the role of IgM antibodies, also referred to as agglutinins in blood?
- bind to A or B antibodies
- anti B antibody = hates A
- anti A antibody = hates B
Do IgM antibodies, also referred to as agglutinins circulate in the plasma or are they attached to RBCs?
- circulate in plasma
IgM antibodies, also referred to as agglutinins circulating in the plasma can come into contact with the wrong blood, this is why they circulate, it increases the chances of identifying a problem with blood type if it is present. What can IGm binding to the wrong blood type do to the blood?
- agglutination also referred to as haemagglutination
What would cause agglutination also referred to as haemagglutination in blood types A and B?
- blood type A receives blood from blood group B
- blood type B receives blood from blood group A
Why would a patient with blood type A receiving blood from a patient with blood group B cause agglutination also referred to as haemagglutination?
- blood group A contain IgM anti-B antibodies in plasma
- IgM anti-B antibodies would bind the B antigens on RBCs
- B antigens are only present on B type RBCs
- IgM anti-B antibodies binding will cause agglutination
A patient with blood type A can receive blood from which patients?
- blood group A and O
A patient with blood type B can receive blood from which patients?
- blood group B and O
A patient with blood type AB can receive blood from which patients?
- blood group A, B, AB and O
- universal receiver
- no antibodies to attack it from any blood type
A patient with blood type O can receive blood from which patients?
- blood group O
- contains both A and B anti IgG antibodies so would attack
What is the universal receiver in blood donating?
- patients with blood group AB
- no antibodies in blood to attack as contains both A and B antigens
What is the universal donor in blood donating?
- patients with blood group O
- no antigens on RBCs so antibodies cannot attack
What is a haemolytic event?
- haemolysis is the rupture of RBCs
What is a direct antiglobulin test (DATs)?
- method to detect a haemolytic event
- detects antibodies that are bound to RBCs
- detects autoimmune or disease
How does the direct antiglobulin test (DATs) detect a haemolytic event?
- IgG, IgM or anti-human globulin is added to an RBC sample
- if antibody binds to RBCs agglutination has occurred
- agglutination confirms haemolytic event
- could be haemolytic anaemia, drug induced or autoimmune
What is the indirect antiglobulin test (IATs)?
- method to detect patients blood type
How does the indirect antiglobulin test (IATs)detect a patients blood type?
- patients RBCs are mixed with various antibodies
- agglutination occurs when blood type A comes into contact with A antigens or anti B comes into contact with anti B antigens
What does anti-human mean?
- something that doesn’t like humans
In the direct antiglobulin blood test why do we need the coombs reagent to detect a haemolytic event?
- blood sample is taken and washed
- any antibodies that are attacking RBCs remain but no agglutination occurs as IgG antibodies are incomplete
- addition of coombs reagent containing anti-human globulin binds to IgG bound to RBCs, acting as a link between antibody/compliment factors and other RBCs
What is gel technology that is used to determine a patients blood type?
- tubes containing buffer, gel and antibody
- if RBCs agglutinates then this is the blood type
- no agglutination = RBCs collect at bottom of the tube
When separating blood where are antibodies found?
- antibodies are proteins
- plasma = proteins
In relation to blood donors what does allogenic mean?
- blood from a donor
If a patient is transfused with the wrong blood type, how quickly do symptoms present?
- with 1-3 hours - called haemolytic shock
What are some common clinical symptoms of haemolytic shock from an incorrect blood transfusion?
- lumbar/chest pain
- headaches
- shortness of breathe
- vomiting
- drop in blood pressure
If the wrong blood transfusion is given patients can go into haemolytic shock, what does this do to the RBCs?
- bodies immune system will destroy new blood
Haemoglobinuria can be caused by an incorrect blood transfusion, what does this mean?
- haemo = blood
- globulin= protein
- uria = urine
- high haemoglobulin in urine
Haemolytic jaundice can be caused by an incorrect blood transfusion, what does this mean?
- immune system destroys new blood cells - increased production of bilirubin
What genes are responsible for the generation of the rhesus blood group?
- RhD = D antigen produced - RhCE = C or E antigen produced
If a patients is Rhesus positive what does that mean?
- patient has rhesus antigens
- a + would be placed after the blood type
- eg: A+, B+, AB+ or O+
What blood can a patient who is rhesus positive recieve?
- and - rhesus blood types
- already positive so rhesus - makes no difference
Why can it be dangerous if mum and baby are not the same for rhesus + or -?
- if mum is rhesus - and baby is rhesus +
- during birth baby and mums blood mix
- mums immunity creates anti-rhesus IgG antibodies
- in subsequent pregnancies mums anti-rhesus IgG antibodies could attack the babies blood if it is rhesus -
How can the risk of mums anti-rhesus IgG antibodies attacking the babies RBCs be detected?
- identify mum and fathers rhesus status - Kleihauer test - detects degree of baby and mums blood mixing
How is the risk of haemolytic disease of the newborn treated?
- mum is given anti-D (D antigen) IgG - given at 28 and 34 weeks of pregnancy
What are the 3 things that can be collected from blood to give to other people?
1 - RBCs 2 - plasma 3 - platelets
Which blood group is the universal blood donor and why?
- blood group O - contains no antigens so other blood groups will not reject this blood
Which blood group is the universal plasma donor and why?
- blood group AB - no antibodies in plasma to attack antigens
Who can a patient with blood group A donate blood to?
- A - AB
Who can a patient with blood group B donate blood to?
- B - AB
Who can a patient with blood group A donate plasma to?
- A - O
Who can a patient with blood group B donate plasma to?
- B - O
What temperature do RBCs need to be kept at and for how long can RBCs be stored at this temperature?
- 4C - 36 days
What can often be done to RBCs to reduce the risk of an immune response in the person receiving the blood donation?
- depletion of leukocytes
- spin the blood and remove the plasma
What temperature does plasma need to be stored at?
- minus 30C
What can be extracted from whole plasma that is involved in the coagulation cascade?
- factors VIII (8) and XIII (13)
What does apheresis mean?
- removal of specific components from blood - requires centrifugation
Even if the correct blood is transfused to patients is it risk free?
- no - always a risk of viral, bacterial or protozoa infections
Why is fluid overload a risk in blood transfusion?
- adding in additional liquid increases stress on body
How can the risk of fluid overload during a blood transfusion be mitgated?
- take a diuretic (increases water excretion) - slow infusion rate
What is haemosiderosis, and why is it a risk following a blood transfusion?
- increased iron content - adding in iron from donated blood
Following a blood transfusion, how often should a patient be checked during the first hour?
- every 15 minutes
Following a blood transfusion, patients should be checked every 15 minutes during the first hour. What needs to be checked?
- temperature - blood pressure - SaO2
Are ABO and Rhesus antigens proteins or carbohydrates (sugars)?
- ABO = carbohydrates (sugars) - Rhesus = proteins (D antigens)
