What are the stages of development in the bone marrow for RBCs?
- Pronormoblast [EPO stimulates pronormoblast differentiation] → Normoblasts → Reticulocytes
What are reticulocytes?
Immature RBCs
Nuceli have not atrophied
Can be released into blood early if marrow is working hard - increased in anaemias if normal working marrow
What is required for the production of RBCs?
Progenitors - stem cells, EPO and other factors
Hb - requires Fe and normal Hb synthesis - deficiency → microcytic anaemia
DNA production - requires Folate and vit B12 for DNA synthesis - deficiency → macrocytic anaemia
Normal protein/membrane synthesis
Describe the process of antigen manufacture for the ABO system
Antigens have a common precursor protein, H
Sugar residues are added to it by enzymes to create antigen
What is an H protein which has no sugar residues added to it?
Absence of any AB antigen binding is represented as O
It is non-antigenic (i.e. antibodies will not bind to it)
What is A antigen blood?
H protein which has A sugar added to it by A-transferase enzyme → A antigen (antigenic)
If an H sugar has a B sugar added to it by B-transferase enzyme, what does it become?
B Antigen blood
Which chromosome contains the gene responsible for ABO blood groups? and what are the 4 possible alleles?
Chromosome 9
O - no transferase enzyme - no ABO antigen produced
A - A-transferase - A antigen produced
B - B-transferase - B antigen prodeced
AB - codes for both enzymes - A and B produced
Against which blood types will one have antibodies against?
Antibodies to A and B antigens naturally occur in patients who lack the antigens on their blood cells
e.g. Anti-A IgM, Anti-B IgM
What happens if the wrong blood type is given to a patient?
Antibodies will attack any RBCs displaying foreign antigens
Cell lysis via complement activation and MAC formation
Wider immune reaction
Anti-D Antibodies are naturally present. True or false?
False. Anti-D antibodies are not naturally present.
Exposure to Rh D in Rh -ve patient will → anti-D IgG
How may RhD exposure occur?
Transfusion
Labour - Rh-ve mother may develop anti-D IgG against baby’s blood if mixing occurs in labour
What are the two types of transfusion reactions in regards to RhD?
Immediate reactions in Rh -ve patients who have pre-existing Anti-D IgG from previous exposure
Delayed transfusion reactions - as patients develop anti-D antibodies which begin to lyse RBCs - hours/days after transfusion
What blood group are universal RBC donors?
Group O RhD -ve
RBCs have no antigens
Cannot receive any other RBCs, as will have antibodies to attack them
Universal plasma recipient - Any antibodies in plasma will not attack host RBCs
What blood group are universal RBC receivers?
Group AB RhD +ve
Can’t have formed antibodies to any antigens
Universal plasma donor - as plasma contains no antigens. Cannot receive any other plasma, as it may contain antibodies which would attack host RBCs.
