L10 - Blood Flashcards
What are blood group antigens?
Proteins on the surface of red blood cells that determine blood donor compatability
What are the 2 major blood group systems?
Give an example of a less common system
ABO system and Rhesus (Rh) system
Kell, Kidd, Duffy, MNS
In the ABO system, what is H substance?
What is its chemical composition?
The base of A and B antigens
Glucose > galactose > N-acetylglucosamine > galactose > fructose
What are the major groups according to the ABO system?
A, B, AB, O
What converts H substance into A antigen?
How is this done?
Enzyme product of the A gene adds an N-acetylglucosamine to the distal galactose, alongside the attached fructose
What converts H substance into B antigen?
How is this done?
Enzyme product of the B gene adds another galactose to the distal galactose, alongside the attached fructose
What are the major characteristics of blood group A in terms of antigens and antibodies present?
A antigen present, anti-B antibodies
What are the major characteristics of blood group B in terms of antigens and antibodies present?
B antigen present, anti-A antibodies
What are the major characteristics of blood group AB in terms of antigens and antibodies present?
Both A and B antigens present, no antibodies
universal receiver
What are the major characteristics of blood group O in terms of antigens and antibodies present?
No antigens present, both anti-A and anti-B antibodies
universal RBC donor, can only receive O blood
What are the most common ABO blood groups in the UK and North America?
UK - O
America - A
What are the main antigens in the Rhesus (Rh) blood system?
Which one is of most clinical significance?
C, c, D, E, e
D
How is a sample’s Rh group determined?
Positive - D antigen present
Negative - No D antigen
What is the most common Rh group?
Positive
What happens to the red blood cells of a type B sample when transfused into a patient who is type A?
The patient’s anti-B antibodies bind to the new blood cells and lyse them
How are risks from donating blood reduced?
4
Donor screening, testing for infections, correct storage, protocols for the use of blood products
How is a patient’s blood group determined?
Add agglutinating anti-A and/or anti-B to patient red blood cells
What is the back group in blood typing and how is it determined?
Whether the patient has anti-A or anti-B antibodies that could affect the donor’s blood
Add RBCs with A or B antigen to patient sample
How is Rh blood typing carried out?
Add agglutinating IgM anti-D to sample, or add IgG anti-D alongside a Coombs test
What are the two types of Coombs (anti-globulin) tests used in haematology?
Direst and indirect
What is the difference between a direct and indirect Coombs test in terms of what they are used for?
Direct - detects Ig bound to RBCs
Indirect - detects non agglutinating Ig against D antigen in serum
What is the difference between a direct and indirect Coombs test in terms of how they are carried out?
Direct - add anti-human Ig to sample, look for agglutination
Indirect - incubate sample with Rh+ RBCs, wash, then add anti-human Ig to see if antibodies from patient serum has bound
Give an example of when a direct and indirect Coombs test would be carried out
Diagnose haemolytic disease of the newborn in a Rh- mother and Rh+ foetus
How would a direct Coombs test be used to test for haemolytic disease of the newborn?
Test baby’s sample for bound maternal anti-D antibodies
Diagnoses condition
