the blood - blood typing & transfusion Flashcards
how long can the different components of blood be stored ?
-red blood cells: up to 35 days (4°C)
-platelets: up to 7 days (25°C)
-plasma: up to 3 years (-30°C)
leucodepletion
removal of WBCs:
-incidence of febrile transfusion reactions
-HLA incompatibility
-transmission of some infections
fresh frozen plasma (FFP)
given to people that are bleeding because they have fun out of one or more clotting factor(s)
-e.g. after severe bleeding
how are patients treated if missing one specific clotting factor ?
often only that factor is replaced by using synthetically made clotting factors
blood transfusion
-essential for treatment of excessive blood loss due to:
=injury or surgery: 27%
=maternity: 6%
=cancer care or anaemia: 67%
-6000 units are needed daily in the UK; annually, 2 mil donations from 1.4 mil donors
qualifications of a safe blood donor
-good health
-unpaid volunteers
-excluding risk factors
=jaundice (hepatitis?)
=travel in malarial areas
=recent tattoo/piercing
=risk factors for HIV or CJD
-screening of blood
-screening of compatibility of donor and recipient
how long must records of blood donations be stored ?
30 years
cell membranes contain many molecules:
-these molecules have lots of different roles (e.g. channels, receptors, identification)
=glycolipids (e.g. ABO Ag)
=proteins (e.g. Rhesus)
=glycoproteins
-antigens (Ag) important to immune system
immune system on non-self & self molecules
-RECOGNISES ‘non-self’ molecules on surface of cells/bacteria/viruses
-IGNORES ‘self’ molecules
ABO group
RBC type
=group A (A antigen)
=group B (B antigen)
=group AB (A & B antigens)
=group O (no antigens)
ABO antigens (Ag’s)
ABO Ag’s are sugar chains attached to the surface of the RBC via the lipid ceramide
gene for the ABO antigens
-ABO blood groups are sugars so there isnt a gene that codes for them
-instead, ABO genes code for glycosyl transferase
-glycosyl transferase is an enzyme that catalases putting the sugar groups together
frequencies of ABO blood group (2018 UK)
O+ : 35%
O- : 13%
A+ : 30%
A- : 8%
B+ : 8%
B- : 2%
AB+ : 2%
AB- : 1%
antibodies (Ab)
-proteins that recognise foreign molecules (Ag) in the body
-trigger an immune response
5 types of antibodies
classified according to their H chain:
-immunoglobin G (IgG)
-immunoglobin M (IgM)
-immunoglobin D (IgD)
-immunoglobin A (IgA)
-immunoglobin E (IgE)
immunoglobin M (IgM)
-made by natural immunity (production of Ab w/o exposure to Ag)
-made out of 5 of the IgGs stuck together
-so IgM is much larger than IgG
antibodies present on the ABO groups
-A: anti-B
-B: anti-A
-AB: none
-O: anti-A and anti-B
ABO antigens and antibodies
-the body makes all of the antibodies (anti-A & anti-B)
-people who are group A (A Ag on surface) will destroy any B-cells that make antibody against self (anti-A)
-but will keep B-cells making antibodies against non-self (anti-B) in their plasma
rhesus (Rh) group
-rhesus is a transmembrane protein on the surface of RBCs
-the rhesus gene is autosomal recessive (most people = rhesus+)
lots of different Rh antigens
- D (most common)
- c
- C
- e
- E
rhesus antigens and antibodies
A+ : A Ag & rhesus D Ag
A- : A Ag
B+ : B Ag & rhesus D Ag
B- : B Ag
O+ : rhesus D Ag
O- : none
AB+ : A Ag, B Ag & rhesus D Ag
AB- : A Ag & B Ag
other blood group antigens
-more than 44 different blood groups
=e.g. Rh, Kell, Fy, Kidd & MN
-not all equally antigenic in transfusion reactions
-ABO strongest
-Rh stronger than other blood groups
=RhD evokes stronger reaction than
the other Rh antigens
natural immunity
IgM antibodies (large) are produced w/o prior exposure to the ABO antigen (anti-A or anti-B)
adaptive immunity
IgG antibodies (small) are produced upon exposure to other RBC Ag’s (e.g. Rhesus)
allogenic
coming from different individuals of the same species but being antigenetically different
consequences of transfusion of incorrectly matched blood
-ACUTE transfusion reaction
-DELAYED transfusion reaction
acute transfusion reaction
-caused by ABO mismatch
-within minutes (acute)
-agglutination by IgM
-complement mediated lysis
-release of Hb (haemoglobinuria)
-breakdown to bilirubin
-toxic (fever, chills, nausea, clotting in blood vessels, necrosis of kidney)
delayed transfusion reaction
-caused by mismatch of non-ABO antigens
-usually due to repeated transfusion of ABO matched blood that is incompatible for other blood group antigens (e.g. Rh, Kidd, Kell etc.)
-first mismatch triggers production of IgG antibody
-on repeat exposure, IgG binds RBCs
-IgG less effective at activating complement (less aggressive symptoms)
-fever, low Hb, increased bilirubin, mild jaundice, anaemia
haemolytic disease of the foetus and new-born (HDFN)
-mother produces Ab that attack baby’s RBCs in-utero
-most common Ag involved = RhD
=(very antigenic/high frequency)
-baby’s symptoms caused by destruction of RBCs
symptoms of HDFN
-enlarged liver and spleen (due to red cell lysis)
-symptoms of anaemia
-jaundice caused by elevated bilirubin
=breakdown product of haemoglobin
(is toxic, may cause brain damage)
cause of HDFN
-RhD(-) mother with RhD(+) baby
-at birth or with trauma, some RBC may cross placenta from baby (or foetus) to mother
-mother raises immune response to foreign Ag on foetal RBCs (IgG)
-in subsequent pregnancies, the anti-Rh Ab can cross the placenta (as IgG) and destroy foetal RBC
prophylactic treatment of HDFN
-anti-D Ab is injected into RhD(-) mother immediately after birth of first child (if RhD(+))
-neutralises RhD(+) red cell from foetus
-no anti-RhD AB raised in mother
-second RhD(+) child does not develop haemolytic disease of the newborn
agglutination assay
-RBCs mixed with two separate solutions of anti-A or anti-B Ab’s to see if they agglutinate
-if the blood clumps, it indicates the presence of antigens in the blood
=e.g. a sample of type A blood will clump when tested with anti-B Ab’s as the blood contains A Ag’s
-type O blood sample will NOT agglutinate either anti-A or anti-B Ab’s as type O blood contains NO antigens
transfusion compatibility
-just RBCs transfused, not whole blood
-O is universal donor
-AB group is universal recipient
blood cross-matching
-blood cells from donation are mixed with plasma from the recipient
-agglutination indicates that the donor blood is incompatible
