Haemotology 2 Flashcards
(113 cards)
1
Q
What is the difference between plasma and serum and their collection methods
A
plasma is the liquid component of blood, to get it whole blood is spun with anticoagulant- a Buffy coat of leukocytes and platelets will form in-between red cells and plasma
serum is plasma without the clotting factors, to get it the blood is allowed to clot and then spun in serum separation tubes.
2
Q
What are the 6 uses of plasma
A
CLOTTING IMMUNE DEFENSE OSMOTIC PRESSURE MANAGEMENT METABOLISM ENDOCRINE EXCRETION
3
Q
Where is serum albumin produced and what does it do
A
in the liver, transports lipids, hormones and ions
it also maintains plasma osmotic pressure
4
Q
Give an example of an Alpha 1 globulin and what it does
A
Alpha-1-Antitripsin
produced by liver, inhibits proteases such as neutrophil elastase which is released after inflammation, this is to help protect tissues.
deficiency in this causes respiratory problems and loss of lung elasticity
5
Q
Give an example of an Alpha-2- globulin and what it does
A
Haptoglobin- binds to the haemoglobin red blood cells release when they die so the spleen can remove it. High levels of haptoglobin indicate haemolytic anaemia
Alpha2 macroglobulin- protease inhibitor that inactivated fibrinolysis
6
Q
Give an example of a Beta Globulin
A
Complement proteins C3 and C4
Transferrin- transports dietary iron and iron from ferritin stores
7
Q
Give an example of gamma globulin and how gamma globulins can be diagnostically used
A
immunoglobulins
C reactive protein
Large fractions of gamma globulin indicate infection or myeloma
8
Q
If ATP is depleted then what happens to cell shape and why
A
Cells become spherical as the ATPase cannot work to maintain ion concentration
9
Q
What are the three main uses of plasma?
A
BIOMARKERS- of disease
PASSIVE IMMUNOTHERAPY- immunoglobulins can transfer immunity, use Intravenous immunoglobulin which has high IgG amounts
HYPERIMMUNE GLOBULIN- take IgG fractions of those with wanted antibodies and give to someone for passive immunity, no memory but helps
10
Q
What is the term for the formation/development of red blood cells, where does it occur and from what
A
Haematopoiesis
blood marrow
from pluripotent hameatopoeitic stem cells which make (1) lymphoid stem cells which make lymphocytes and (2) myeloid stem cells which make erythrocytes, platelets, granulocytes, monocytes, eosinophils, mast cells and basophils
11
Q
Hameatopoeietic stem cells have high two properties
A
1) ability to self renew so the HSC pool isn’t depleted
2) ability to differentiate to mature progeny -daughter cells differentiate and become more committed to a single linage the more they differentiate
12
Q
What are the sites of haematopoeisis from foetus to older
A
Yolk Sac- generates HSC
Liver- maintains HSC and expands
Bone Marrow in adults
13
Q
What regulates haematopoeisis
A
genes, transcription factors, growth factors and microenvironment: balances proliferation (could lead to leukaemia) and differentiation (bone marrow failure)
Glycoprotein hormones are a growth factor they bind to the surface receptor and regulate proliferation and differentiation of HSCs
They include: ERYTHROPOEITIN (erythropoiesis) and G-CSF, G-M CSF, cytokines \9for granulocyte and monocyte stimulation)
14
Q
What does the common lymphoid progenitor and myeloid progenitor turn into and what happens as differentiation progresses
A
Lymphoid ->
B cell progenitors in bone marrow
T cell progenitors in thymus to bone marrow
Nk cell progenitors in bone marrow
Myeloid->
Erythroid
Megakaryocyte 9platelet)
Granulocytes-monocyte
as differentiation progresses self renewal and lineage plasticity decrease
15
Q
What are the requirements for erythropoiesis and if there is a deficiency in one what happens
A
Folate
Iron
Vitamin B12
Erythropoeitin
anaemia
if iron deficiency - microcytic cells : pregnancy, childhood, low resource
if B12 or folate deficiency- Macrocytic cells: alcohol excess, pregnancy, vegan
16
Q
Where is erythropoietin made and how does ti work
A
Made in kidney is a glycoprotein, made in response to hypoxia (anaemia) so DEMAND SUPPLY FEEDBACK LOOP. more erythropoietin made will make the bone marrow produce more red blood cells so there will be more oxygen in blood and the kidney will stop producing erythropoietin
17
Q
Describe the functions of Iron, what forms of iron are there and, iron homeostasis
A
1) oxygen transport
2) mitochondrial proteins - cytochromes a b and c
iron absorbed in duodenum: Haem iron is ferrous Fe2+ and best absorbed. Non haem iron is ferric 3+ and needs Vitamin C for absorption as they contain phytates
iron absorption is tightly controlled as not excreted and can be toxic.
Hepcidin regulates by blocking ferroportin so it can’t bind to transferrin and move into blood
18
Q
How is erythropoiesis regulated
A
pro inflammatory cytokines - IL-1, IL-6, IFN gamma, TFNalpha all inhibit erythropoeisis, they decrease erythropoeitin production and can work on liver to increase hepcidin which will lower Iron absorption, availability and transport
19
Q
Describe the functions of Vitamin B12 and folic acid, where they come from and what deficiencies in them may result from
A
Vitamin B12- meat, egg, fish
Folic Acid- green leafy vegetables, fruit, Whole grain cereal
B12 combines with IF in the stomach so the duodenum doesn’t digest it and binds to cubulin receptor in ileum.
B12 deficiencies may result from: inadequate intake, inadequate IF secretion- pernicious anamia, malabsorption, lack of stomach acid after surgery etc
Vitamin B12 and flat both are needed for dTTP synthesis (DNA precursor) to make thymidine
so deficiency will affect all dividing cells: bone marrow, epithelial surfaces etc
Folic acid is also absorbed in the small intestine and requirements increased in response to higher red cell production like in sickle cell anaemia or haemolytic anaemias and during pregnancy too
20
Q
How are red cells broken down
A
Destroyed by macrophages in the spleen after its circulated for 120 days
iron from haem goes back to bone marrow and bilirubin is excreted in bile
21
Q
Erythrocyte function depends on what
A
Integrity of the membrane: biconcave so flexible through blood vessels, lipid biller supported by protein cytoskeleton and transmembrane proteins which have vertical and horizontal linkages.
Haemoglobin structure and function:
Cellular metabolism: generates ATP to meet energy requirements to maintain cell integrity and volume
22
Q
Disruption in the linkages in blood cell membranes cause what
A
VERTICAL LINKAGES- hereditary spherocytosis- loss of cell membrane without loss of cytoplasm so become round
HORIZONTAL LINKAGES- Hereditary Elliptocytosis- elliptocytes form
23
Q
Deficiency of what in metabolism affects red blood cells, what happens if you’re deficient in it and how do you know
A
Glucose-6 phosphate dehydrogenase: needed for HMP shunt which is needed for glutathione metabolism to protect red blood cells from oxidant damage
Deficiency in G6PD causes intravascular haemolysis when faced with infection or exposure to an exogenous oxidant like drugs or broad beans.
Intravascular haemolysis makes BITE cells/ contracted cells: small no central pallor. the oxidant damage denatures haemoglobin making Heinz bodies which are round inclusions and then the spleen removes the damage
24
Q
What are the granulocytes
A
Basophils, neutrophil, eosinophil and monocytes
they shave granules in the cytoplasm and signal through G-CSF, GM-CSF, M-CSF
cell division occurs in all stages but not metamyelocytes or band forms
25
What are neutrophils and how do they migrate
survives 7-10 hours
nucleus is segmented/lobulated
defence against infection it phagocytosis and kills
Chemotaxis causes neutrophils to move to tissues, marginated within the vessel lumen, adhere to the endothelium, roll, diapedisis and migrate into the tissues. There they phagocytose microorganisms
26
Describe eosinophils
Less Time in circulation more in tissue
bilobed will stain red
defence against parasitic infection
27
Describe basophils
contains histamine, heparin and proteolytic enzymes in granules
are dense and very rounded
involved in allergic response
28
Describe monocytes
days in circulation
phagocytose and present antigens
monocytes migrate to tissues where they develop into macrophages
broad bean shaped nucleus
29
What are the cells developing from the common lymphoid progenitor, how do they circulate and what are their function
B cells, T cells and NK cells
they recirculate to lymph nodes and other tissues then back to the blood stream
B cells mature into plasma cells and make antibodies (larger cell with round nucleus lots of pale ares) humoral response
T cells are involved in cell mediated immunity (round nucleus but less cytoplasm)
NK cells are part of innate immune system and kill cells (weird shaped nucleus has granules)
30
What changes/problems can cause a difference in number or morphology of white cells
REACTIVE OR SECONDARY CHANGES- healthy bone marrow response to infection, inflammation or infarction : raised number of neutrophils
PRIMARY BLOOD CELL DISORDERS- number or morphology abnormaldue to somatic DNA damage that affects a precursor : leukaemia, lymphoma, myeloma
31
What are the terms of the abnormalities have fewer or more neutrophils
LEUKOCYTOSIS- too many usually neutrophils but can be : neutrphilia, eosinophilia, basophilia, lymphocytosis, monocytosis
LEUKOPENIA- reduction in white cells:neutropenia or lymphopenia
32
Describe neutrophillia and the disorders its associated with
neutrophilia is due to infection, inflammation and tissue damage, can be seen in pregnancy or after exercise or taking corticosteroids (as neutrophils shift from marginated to circulating pool). may be associated with left shift (more non segmented precursors) and toxic changes
Toxic granulation is a feature of pregnancy
myeloproliferative disorder: CHRONIC MYELOID LEUKAEMIA: primary blood cancer associated with neutrophilia, basophilia and left shift. Its due to translocation between chrmsm 9 and 22 resulting in Philadelphia chrmsm which creates BCR-ABL1 gene which has tyrosine kinase activity and drives blood cell proliferation.
causes splenomegaly but can be inhibited by tyrosine kinase inhibitors.
33
Describe neutropenia and the disorders that come from this
Too few neutrophils
following hemotherapy and radiotherapy
from autoimmune disorders, bacterial infections, viral infections and drugs (anticonvulsant antimalarial)
low neutrophil counts= infection risk
34
What is neutrophil hypersegmentation
Right shift, more lobes segments
| lack of vitamin D or folic acid (megaloblastic anaemia)
35
What can leukocytosis be a result of and an example
Lymphocytosis (transient with infection): viral infection, lymphoproliferative disorder (primary blood cancer), whooping cough in children. Eosinophilia- parasitic infection (asthma, eczema)
Basophilia- leukaemia or blood related
monocytosis- bacterial infection or chronic inflammation, some leukaemia
persistent leukocytosis = chronic lymphocytic leukaemia see smear or smudge cells -cell surface markers would help to find out cause.
36
Acute vs chronic lymphoid leukaemia
In both bone marrow is infiltrated by lymphoblasts causing haematopoeisis problems.
Acute lymphoblastic- severe and sudden onset : immature cells
Chronic lymphocytic- leukaemia cells are mature but abnormal
37
What are the features of Acute lymphoblastic leukaemia and how can it be treated
lymphocytosis with lymphoblasts in the blood: look immature
Anaemia - will be pale
neutropenia
thrombocytopenia - will show as bruising on skin
Red cells, platelets and antibiotics to support
systemic and intrathecal chemotherapy
38
What are some causes of lymphopenia
HIV infection (blocks CD4) , chemotherapy, radiotherapy, corticosteroids
39
What is haemostasis
state of equilibrium, results from
vasoconstriction
primary Haemostasis making unstable platelet plug
secondary haemostasis making soluble fibrin clot
40
Describe primary haemostasis-
Platelet Adhesion and Aggregation: Damage to the endothelial cells makes von Willebrand and platelet will bind via their G1b receptors (G1a if binds to collagen). Adhesion activates then and release ADP, fribrinogen and serotonin from granules. Adhesion also stimulates platelets to synthesise the prostaglandin Thromboxane A2 from arachidonic acid. Thromboxane A2 and ADP have a positive feedback effect and activate other platelets by binding to P2Y12 and Thromboxane A2 receptor and will cause them to move, bind and aggregate. The platelets bind together when fibrinogen binds to the GIIb/IIIa receptors forming the platelet plug.
Thromboxane A2 and serotonin are also vasoconstrictors
41
What molecule suppressed platelet activation normally
Prostaglandin and the active movement of blood
| prostaglandin is a vasodilation and stops platelet activation
42
What anti platelet drugs are used to stop blood clotting
ASPIRIN: blocks acton of cyclo-oxegenase which catalyses the conversion of arachidonic acid into thromboxane A2 , this stops platelet aggregation. However endothelial cells can synthesis more COX but platelets can't so, wears off after 7 days (platelet lifespan)
CLOPIDOGREL: blocks ADP receptor P2Y12 on the platelet cell membrane so stops platelet recruitment and aggregation. lasts for 7 days
43
What is von Willebrand factor
A glycoprotein that is synthesised by endothelial cells, circulates in plasma as MULTIMERS of different sizes. allows platelets to adhere to sites of injury, also carries factor VIII
44
Where are the different clotting factors produced and what are some dependent on
everything apart from VIII and VWF is made in the liver
VIII and VWF is made by endothelial cells (VWF by megakaryocyets too)
2,7,9,10 are dependent on vitamin K to carboxylate glutamic acid residues
45
Describe secondary haemostasis
Each step is conversion of an inactive zymogen to an active clotting factor , works on exposed phospholipid of platelets. Calcium helps to bind clotting factors to platelet surface
INITIATION: At the area of tissue damage tissue factor which is (Factor III) is exposed and binds to 7a. this causes 9 to 9a and 10 to 10a. 10a activated prothrombin (2) to become thrombin (2a)
AMPLIFICATION: thrombin (2a) mediates the activation of cofactors 8 and 5 to 8a and 5a as well as 11 to 11a.
PROPAGATION PHASE: 11a converts more 9 to 9a and with 8a converts 10 to 10a making a burst in thrombin generation
This cleaves the circulating fibrinogen and forms the insoluble fibrin clot
46
What mechanisms confine clotting to the site of injury and prevent spontaneous coagulation naturally
Protein C
Protein S
Antithrombin
Thrombin binds to thrombomodulin on the endothelial cell surface activating protein C (APC) APC inactivates factors 5a and 8a when protein S is present which stops the burst in thrombin generation as 9a and 8a work together to activate 10
Thrombin and factor 10a are inactivated by antithrombin. Antithrombin is potentiated by heparin
47
What anticoagulation drugs are used in the prevention of thrombosis, how do they work and how are they administered
HEPARIN: mix of GAG chains, works INDIRECTLY by potentiating action of antithrombin to stop 10a making 2a. Need long heparin chains that will wrap around antithrombin and thrombin. Administer I.V or subcutaneous injection
WARFARIN: Vitamin K agonist so stops the protein carboxylation of glutamic acid residues. Reduced 2,7,9,10, takes several days to take effect as reduces coagulation factors being made not existing ones. Given orally as tablet need regular blood testing
DIRECT ORAL ANTICOAGULANTS: DIRECTLY inhibit thrombin or 10a. orally available
48
Once a clot has ben made how does the body break down clots
fibrinolytic enzyme: plasmin
plasmin circulates as plasminogen, to activate it needs tissue plasminogen activator and them both to be bound to lysine residues on the fibrin clot.
plasmin then causes fibrinolysis and turns the fibrin clot into fibrin degradation products
49
What therapies or drugs can be given to those at risk of clotting or who have blood clots
THROMBOLYTIC THERAPY: those with iscahemic stroke or other blocks can be given thrombolyitc therapy which is thrombolytic agents like recombinant t-PA. They work to help generate plasmin to lyse the clots. given I.V as quick as possible but high risk of bleeding
50
What can be given to those who are at risk of bleeding
```
TRANEXAMIC ACID (antifibrinolytic drugs): tranexamic acid is a derivative of lysine which is what plasminogen binds to. It competes for the lysine residue sites (competitive inhibition) and prevents activation of plasmin so fibrinolysis does not occur and it stays clotted.
used in trauma and surgical patients as well as those with bleeding disorders.
```
51
How can coagulation pathways be tested and reduction in what means what factors are reduced
APTT: Intrinsic pathway : activates 7 with contact to surface, time taken to clot is measures, prolongation of APTT = reduction in clotting factors. If only APTT that is prolonged with a normal PT then haemophilia A(8 deficiency), B (9 deficiency) and factor 11 deficiency. even factor 12 deficiency which doesn't cause bleeding
high APTT= problem with 12,11,9,8
PT: Extrinsic pathway : Time taken to clot is recorded, PT is prolonged if factors 7, 10, 5, 2(prothrombin) or 1 (fibrinogen) is reduced
52
Bleeding is caused by what
1) reduction in platelet number
2) reduction in coagulation factors
3) increased fibrinolysis
53
what is thrombosis and what factors contribute to venous or arterial thrombosis
formation of blood clot in an intact vessel, obstructing the flow
Blood (constituents) in venous thrombosis
Vessel walls in arterial thrombosis
blood flow in both
54
What changes in blood increase the risk of venous thrombosis and when do these changes occur
1) less anticoagulant proteins like antithrombin :genetic diseases cause this
2) less fibrinolytic activity- e.g. pregnancy inhibits plasminogen activation
3) High levels of clotting factors (8 increases in pregnancy, 5 increases in mutation in 5 gene : factor V Leiden, makes resistible to protein C stopping action of factors 5 and 8)
4) high levels of platelets in myeloproliferative disorders
55
What property of oxygen binding by haemoglobin makes it easier to bind more each time
Positive cooperative: binding of oxygen results in a change and it positive as affinity increases each time, allows to deliver more oxygen
56
How is oxygen binding to haemoglobin controlled
By 2,3,BPG which binds to a site in deoxyhaemoglobin away from heme groups. it stabilises and reduces affinity for oxygen : ALLOSTERIC EFFECTOR
reduced affinity = right shift
57
In the oxygen dissociation curve what effect with foetal haemoglobin, myoglobin, carbon monoxide, anaemia, polycythamia have ?
Polycythamia= more blood cells, upward shift as higher oxygen carrying capacity
Anaemia. downwards shift, less total blood cells to carry oxygen =lower capacity
Carbon monoxide- down and left, it increased haemoglobin affinity for oxygen it binds to but take away oxygen bidding sites - lower capacity and higher affinity
foetal haemoglobin- greater affinity than HbA for O2 to get oxygen from mothers blood- higher affinity (left shift),( reduced affinity to 2,3BPG)
myoglobin- much much greater affinity to extract oxygen and store it for high intensity activities- high affinity (left shift loses sigmoid shape)
58
What are the subunits of HbA, HbA2 and HbF and what switched at birth
HbA- alpha2 beta2
HbA2- alpha2 delta2
HbF- alpha2 gamma2
at birth the gamma switches to beta so less HbF nd more HbA
59
How will higher/lower temperature, Co2 concentration, 2,3,DPG and alkalosis/acidosis affect the oxygen dissociation curve
LEFTWARD SHIFT- lower temperature, lower 2,3 DPG, alkalosis(low proton), low CO2
RIGHT SHIFT- high temperature, high 2,3 DPG, acidosis, high CO2
60
What is methaemoglobin and how does it work, what shift does it cause
ferrous iron oxidised to ferric so oxygen can't bind as early. shift leftwards could cause tissue anoxia as not readily released
61
In electrophoresis will HbA or HbS travel further to the negatively charged cation and why
HbS will travel further towards the negative cation than HbA.
HbA is more negative because it has glutamate which is negatively charger, HbS however instead of glutamic acid has valine which is uncharged making it more positive and more likely to move to the cation
62
What are the key words to describe the size of a red blood cell and name some examples of what causes them
Microcytic- small - iron deficiency which stops Haemoglobin synthesis, defect in global synthesis alpha or beta chain which leads to alpha or beta thalassaemia
Normocytic-normal sized
Macrocytic- larger- can be round, oval or polychromatic (immature). Can be due to Lack of Vitamin B12 or folic acid which causes megaloblastic anaemia, can also be due to liver diseased ethanol toxicity, haemolysis and pregnancy
63
What terms are used to describe red blood cell colour
Hypochromia/Hypochromic- larger central pallor than normal due to lower haemoglobin content+ concentration and a flatter cell, usually microcytic
Polychromasia/Polychromatic- increased blue tinge to the cytoplasm of a red cell- indicates the red cell is young - will usually be Macrocytic
64
How are young red cells detected and described and what is their cause
Stain for reticulocytes, stain for higher RNA content
| reticulocytosis- is the presence of increased numbers of reticulocytes and may occur due to hameolysis
65
How to describe the difference in red blood size, shape if it is not consistent on examination.
Anisocytosis- more variation in size than normal
Poikilocytosis- red cells show more variation in shape than normal-
66
what different shapes of red blood cells are there and what are diseases problems are they linked to ?
target cells- red cells with a dot of haemoglobin in the middle. may occur due to obstructive jaundice, liver disease, hyposplemism
sickle cells - sickle shaped from the polymerisation of HbS which is less soluble than HbA, occurs when have one or two copies of abnormal beta globulin gene which replaces glutamic acid with valine. sickle cell anaemia
irregularly contracted/bite cells -
fragments /schistocytes- small pieces or red cell may result from shearing process by platelet rich blood clots
spherocytes- rounds, reduced membrane
elliptocytes
67
How is a reference range made
From a reference population: samples from healthy people with defined characteristics, use an appropriate statistical technique
68
How does sickle cell anaemia occur
missense situation at codon 6 of beta globulin chain, glutamic acid(polar and soluble) is replaced by valine (non polar and insoluble)
HbS is insoluble and polymerises to form tactoids that distort the red blood cell and make a sickled shape
```
HbSS= sickle cell anaemia
HbAS= sickle cell trait
```
69
What are the effects of sickle cell anaemia
Haemolysis of sickled red blood cells- shortened lifespa, anaemia as less Hb concentration, jaundice and gall stones from increase red cell breakdown products, parvovirus B19 shuts erythropoiesis down,
Vasoocclusion- blocks microvascular circulation which causes pain, dysfunction, tissue damage and necrosis
70
How does HbS affect the oxygen dissociation curve
right shift as low affinity for oxygen
71
When does sickle cell disease present and with what symptoms
Symptoms rare before 4-6 months of age as this is when HbF switches to HbA
Dactylitis (inflammation of digits), splenic sequestration(RBC pool in spleen),infection
72
What does the spleen do and how can HbSS affect it
Spleen is involved in immune defence and the breakdown+removal of old malformed or damaged red blood cels
splenic vasooccluson leads to functional hyposplenism- stops working- the increases susceptibility to encapsulated bacterial infection will need immunisation and prophylactic antibiotics.
73
What is acute chest syndrome in SCD and what other conditions are linked
pulmonary infiltrate on chest X-ray (white on x-ray) with fever, cough, chest pain
Stroke- major cerebral vessels, most common in childhood
Avascular necrosis of the femoral head
osteomyelitis due to infection
gallstone prevalence high
74
What are the laboratory features of SCD
Hb low - 60-80
Reticulocytes high
see sickled cells, boat cells, target cells and Howell Jolly Bodies which have a dark dot at the edge showing DNA hasn't been expelled
75
How is SCD diagnosed
Sickle solubility test : in presence of oxyHb the solubility will decrease and the solution will be turbid/ can't see through
Sickle solubility doesn't differentiate As from SS so need electrophoresis
76
What is haematocrit
Volume of red blood cells as a ratio of whole blood volume is in L/L
77
How is Mean Cell Volume, MC Haemoglobin and MC haemoglobin concentration calculated and what do they mean
MCV= Hct(as decimal)/RBC - finds the average volume of each blood cell (L)
MCH= Hb/RBC - finds the average mass of hb in each RBC (g)
low MCH would make pale cells on smear
MCHC= Hb/Hct(decimal) - finds the average concentration of Hb in each red blood cell (g/L)
low MCHC would mean anaemia, high would mean circular cells
L -> fL = x10 (^15)
g ->pg = x10 (^12)
g/L -> g/dL = /10
78
What is a blood group and a blood group system
| Which blood group systems are most clinically significant and why
Blood group is the combination of antigens that are present on the plasma membrane
Blood group system is a collection of one of more RBC antigens under the control of a single gene or cluster of closely liked genes
ABO and Rh- clinical importance depends on capacity of antibodies against specific RBC to cause haemolysis
79
Antibodies against RBS antigens are clinically significant if they can cause what
Haemolytic transfusion reactions- incompatible red cells are transfused e.g patient has antibody B and B blood is transfused
Haemolytic disease of the foetus and newborn- foetus has a different RBC to mother and mother has antibody to that RBC
80
What are the two types of antibodies against RBC antigens
1) Naturally occurring antibodies-
anti A/ anti B are naturally occurring and stimulated when the missing blood group is encountered in foods etc
the interaction of pentameric IgM and RBC antigens in vitro causes agglutination
IgM ABO antibodies can cause HTR through activation of complement system but can't cross placenta, cause massive intravascular haemolysis
2)Acquired alloantibodies
active immunisation to non self RBC after exposed to another individuals RBC may be due to incompatible blood transfusion or pregnancy
Acquired alloantibodies are usually IgG cause extravascular haemolysis causing delayed HTR and can cross the placenta
81
How are the A and B antigens formed
Theres a common glycoprotein and glucose stem which is called the H antigen
The A gene codes for an enzyme that adds N-acetyl galactosamine (GalNac) to the common H antigen resulting in the A antigen
The B gene codes for an enzyme that adds galactose (Gal) to the common H antigen resulting in the B antigen
The A and B genes are co-dominant so presence of both genes results in formation of both A and B antigens
The O gene produces an inactive enzyme so the H antigen remains unchanged and neither A nor B antigen can be formed . The O gene is recessive.
82
Are ABH antigens only on red blood cells and why are there different prevalences of groups in different populations
ABH antigens expressed in many tissues
Frequency of group differs between ethnic groups, gives survival advantage e.g. O has a survival advantage against malaria
Blood groups are also impact susceptibility to infection as they are receptors for toxins parasites and bacteria, can be false receptors or bacterial pathogens can carry ABO antigens and not be recognised
83
Why does IgG not usually cause haemolytic disease of the newborn and foetus even thought it can cross the placenta
Fetal red blood cells have poorly developed About antigens which can't support binding of IgG antibodies
ABO antigens are found in numerous other cells so the IgG could bind to these cells
HDFN occurs in mothers who have hight titres of anti a or anti B antibodies
84
When selecting blood components for transfusion what ones do you need to match to Abo group
Red cells- ABO compatible to prevent HTR, in emergency Group O
Platelets- same ABO if patient has a high titre of anti A or anti B. if they are high titre negative then give any
85
What are the two Rh groups and why are they clinically significant
```
RhD positive (has a dominant D allele)
RhD negative (recessive) can make anti-D antibody
```
significant because can cause HTRs if positive are given to negative and HDFN if negative mother is carrying positive child as IgG anti-D can cross placenta - If this happens then given anti-D immunoglobulin which will destroy the positive fetal RBC's in circulation before the mother makes anti-D
86
When selecting blood components for transfusion which ones need to be matched to Rh group
Red cells- same Rh type, negative to positive is also okay
Platelets- platelets should be same group as units can contain small fragments . if RhD+ have to be given to RhD- then anti-D immunoglobulin should be administered
Fresh frozen plasma- any type as don't contain RBC
87
How to determine a patients ABO blood group
FORWARD GROUP- patients RBC is tested against anti ABO antibodies, whatever clumps is what group they are if they're O they will have no reaction to antibodies as don't have antigen. AB will react to both A and B
REVERSE GROUP- patients serum (which contains the anti a/b antibodies) is mixed with A and B red blood cells. If there is no reaction then it means that is their blood group. O will react with both as have anti-A and B antibodies, AB won't react
88
How to determine a patients RhD group
use patient red cell and anti-D antibodies
RhD+ will react since they have D antigens
RhD- won't react since they don't have D antigens
89
What is an antibody screen and what is a cross match
Detect any alloantibodies that have developed
if there's an interaction then agglutination will occur
For red cell transfusions a cross match is performed before the unit of red cells is administered, test patients plasma against sample of RBC's from unit of red cells no agglutination means compatible, agglutination means it snot
90
How are blood donors selected and tested
Giving blood can't be hazardous for them or the recipient
Donor education and self exclusion if they are at high risk of having a blood borne infection as early stages of infection is undetectable
donor health check questionnaire and health screening interview
group and screen : determines About and R, check for any clinically significant antibodies in donors plasma
Infection screening: screened for HIV, hepatitis B,C,E, HTLV and syphilis
91
What are the two ways blood is collected from volunteers
1) whole blood donation- blood collected in its entirety then centrifuged into components
2) Apheresis- donor connected to aphaeresis machine which separates out particular component and the remainder is retuned.
92
What are the plasma derived products and how are they made
Pooling of plasma via fractionation. Viral inactivation through heat treatment and use of solvent detergent
Human albumin solution
Immunoglobulins
Clotting factor concentrates
93
When are red cells transfused, how many units from each collection method, how does one unit change the blood and what is shelf life
Required to increase haemoglobin and restore oxygen carrying capacity - LOW HB IN ANAEMIA OR BLOOD LOSS,
known as packed red cells
1 unit from whole blood donation, 1-2 from aphaeresis
1 unit increases Hb by 10g/L
shelf life of 35 days a 4 degrees
94
When are platelets transfused, how many units from each collection method, how does one unit change the blood and what is shelf life
TREATMENT OF BLEEDING OR TO REDUCE RISK IN THOSE WITH LOW PLATELETS (thrombocytopenia) or PLATELET DYSFUNCTION
pooled platelets are 4 whole blood donations put together to make one unit of platelets
aphaeresis platelets- single donor donates 1 unit
1 unit increases by 10x10^9 litres
Shelf life of 7 days, stores at room temperature need continuous agitation
95
What is fresh frozen plasma, when is it transfused, how many units from each collection method, how does one unit change the blood and what is shelf life
Fresh frozen plasma contains all the coagulation factors needed to treat bleeding or risk of bleeding (have prolonged PT, APTT or both)
1 unit from whole blood or apheresis
check PT and APTT after transfusion
shelf life of 3 years at -25 C, must be thawed in waterbath and used within 24 hours
96
What are the two common causes of coagulopathies
dilution: significant bleeding and only red cells transfused
consumption: disseminated intravascular coagulation
97
What is cryoprecipitate, when is it transfused, how many units from each collection method, how does one unit change the blood and what is shelf life
Contained fibrinogen, Factor 8, von Willebrand factor and factor 13
treat bleeding or reduce tis of bleeding when fibrinogen level is low which is usually because of major haemorrhage or disseminated intravascular coagulation
1 unit from a single donation or 5 donors pooled together
cryoprecipitate is made by thawing fresh frozen plasma overnight until there is precipitate, precipitate re suspended in a small volume of plasma and frozen to maintain activity of clotting factors
dose Is 2 units which increase fibrinogen by 1g/L
3 years at -25C, towed in a waterbacth and used within 4 hours
98
What are the plasma derived products used for
Human albumin solution- replace plasma volume (burns trauma decreases), replace plasma in plasma exchange (treatment of autoimmune disorders), initiate diuresis in those with low albumin
Immunoglobulin solution-
1) Normal- antibodies to common viruses, protect those more susceptible to them. High dose I.V immunoglobulin is used as a replacement therapy for those with immunoglobulin deficiency and in treatment of autoimmune disease
2) specific immunoglobulins- from selected donors with high antibody to target of treatment e.g anti-d immunoglobulin, hep b, tetanus
Clotting factor concentrates
1) single factor- manage most coagulation deficiencies
2) prothrombin complex concentrates- 2,7,9,10, reverse affects of warfarin , manage patients with major bleeding and haemorrhage. takes less time than trying to thaw fresh frozen precipitate
3) Fibrinogen- alternative to cryoprecipitate
99
What is leukaemia, what causes it and what are the types
bone marrow disease, overspill of abnormal cells into the blood
arises due to a mutation of myeloid or lymphoid cells. This mutation in the primitive cells prooncogenes/tumour suppressor genes has a growth or survival advantage over normal cells. This mutation makes a clone which starts to replace normal cells. Mutation may start due to mutagens but may be random, in an elderly person enough mutations may accumulate for the cell to mutate and clone. . The leukaemia clone grows without dependence on growth factors, continues proliferation without maturation and fails to undergo apoptosis.
Abnormal cell circulate in the blood stream and migrate into tissues, hard to compare it to normal cancers metastasis.
Acute- if untreated death in days
Chronic- impairment of function slowly
leukaemia can be acute, chronic, lymphoid, myeloid
100
Describe the two types of acute leukaemia and which age groups they affect mostly
Acute myeloid leukaemia may be spontaneous as well as a consequence of environmental mutagens, usually older people.
Acute lymphoblastic leukaemia- occurs in infants and the mutations occur during fatal development, antigenic stimulation may eye linked leading to the rearrangement of DNA so greater affinity antibodies new made- this can give rise to a malignant phenotype
101
What is the difference between the mutations in chronic and acute leukaemia
Acute leukaemia- mutations in genes encoding transcription factors, stops cells maturing but they keep proliferating making blast cells, lymphoblasts or myeloblasts,
Chronic myeloid leukaemia- mutation involves activation of signalling pathways, can proliferate without needing growth factors, maturation still occurs,
chronic lymphoid leukaemia- less understood but still a clone, expanding and impaired tissue function
102
What are the signs and symptoms of leukaemia
1) direct effect of the proliferation- bone pain, heptomegaly, splenomegaly, swollen lymph nodes
2)indirect effect- replacement of normal bone marrow cells by leukaemia cells-
anaemia- fatigue
neutropenia- fever and infection
thrombocytopenia- bruising and
bone marrow expansion- bone pain
abdominal enlargement- hetamegoly, splenomegaly
lumps nd swelling
103
what investigations are essential for leukaemia
Full blood count and a blood film
| Flow cytometry- characterise the profile of the cell surface markers expressed like the Philadelphia chromosome
104
What is anaemia and how is it caused and classified
Reduction in Hb concentration, reduction in RBC and Hct
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Due to:
reduced production of red cells
loss of blood from body
reduced survival- haemolysos
increased pooling and enlarged spleen
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can be microcytic, Macrocytic and Normocytic
105
What are the common causes of microcytic anaemia
Appear pale (hypochromia) look small
causes: iron deficiency anaemia(reduced Haem synthesis), anaemia of chronic disease, thalassaemia (reduced globin)
iron deficiency can be due to blood loss (hookworm, menstrual), insufficient intake via diet or malabsorption, increased requirements
106
What are the three stages of iron depletion
Iron depletion: storage iron reduced or absent
Iron deficiency: low serum iron and transferrin saturation
Iron deficiency anaemia: low haemoglobin and haematocrit
107
What are the clinical features of iron deficiency anaemia
Pallor, fatigue, breathlessness
failure to thrive- impaired intellectual development
koilonyhcia and angular chelitis
108
What are the common causes of anaemia of chronic disease
Rheumatoid arthritis, malignancy, autoimmune disease, kidney disease, HIV or Tb infections
NF alpha and interleukins lead to a decrease in erythropoietin production and prevent normal iron flow to red blood cells.
109
What are the laboratory clues that its anaemia of chronic disease vs iron deficiency
C-reactive protein is high (wont be in iron deficiency)
Erythrocyte sedimentation rate (ESR is high) (wont be in iron deficiency)
Ferritin is high (in iron deficiency its low)
Transferrin is low (in iron deficiency its high)
acute phase proteins increase
110
What are the causes of Macrocytic anaemia
Abnormal haematopoeisis, red cell precursor synthesis hemoglobin and cellular proteins but don't divide normally.
Causes:
megaloblastic erythropoiesis: delay in maturation of nucleus while everything else grows, megaloblasts are usually found in bone marrow not blood film and show nucelocytjoplasmic dissociation. GROW BUT CANT DIVIDE IN MLB
lack of vitamin B12 or folic acid
Drugs interfering with DNA synthesis
liver disease and ethanol toxicity
major blood loss or haemolytic anaemia (reticulocytes increase- young cells are larger)
111
What is Normocytic anaemia and the common causes
Normal staining and normal size- normochromic Normocytic
Due to : recent blood loss (GI haemorrhage or trauma), failure to produce red cells (bone marrow failure-chemo or infiltration- leukaemia), pooling of cells in spleen (hypersplenism)
112
What is polycythaemia and what are the causes
Too many red cells in the circulation- Hb, RBC and Hct are increased
can be pseudo where its just plasma volume is reduced
or true- higher amount of red cells
if it is true:
1) blood doping or overtranfusion - doping to increase red cells to increase oxygen carrying capacity
2) appropriately increased erythropoietin- as a result of hypoxia like if at high altitude (central cyanosis- blue discoularation of lips due to low levels of oxygen)
3) inappropriate erythropoietin synthesis- can be cyclists administered or a kidney tumour that caused more EPO secretion
4) independent of erythropoietin- intrinsic bone marrow disorder caused polycythaemia vera (myeloproliferative disorder) - blood is hyperviscous can lead to thrombosis
113
Why is important to distinguish between iron deficiency and thalassaemia and how is it distinguished
Replace iron where deficient, not incorrectly prescribe iron supplements which won't help thalassaemia its dangerous
Important to advice thalassaemia traits on potential risks with children and passing them on
Electrophoresis- High A2 for beta thalassaemia
RBCount
Iron Studeis- serum ferritin would be low in Iron deficiency
