Haematopoiesis and anaemias Flashcards
types of blood cells?
Red cells, Platelets, White cells
where and when does haematopeisis occur?
After birth, and during early childhood, hematopoiesis occurs in the red marrow of the bone. With age, hematopoiesis becomes restricted to the skull, sternum, ribs, vertebrae, and pelvis.
regulation of haematopoeisis
Regulated by variety of glycoprotein hormones, including stem cell factor, granulocyte-macrophage colony-stimulating factor, thrombopoietin and IL-3.
in normal peripheral blood, role of... -platelets - red cells - white cells
clotting
O2 transport
immunity + infection response
How do platelets work?
have no nucleus
The granules secrete substances which control clotting and the breakdown of blood clot
what do platelets form part of?
blood clot
What is a platelet’s life span
8-12 days, then removed by macrophages (WBC type) in the spleen and liver
What do low levels of platelets lead to
and what is it a side effect of?
Easy bruising and haemorrhage
chemotherpay/disease
types of white cells (leucocytes)
lymphoid cells (lymphocytes)
- T cells
- B cells
- NK cells
myeloid cells
- monocytes
- granulocytes
- eosinophils
- basophils
- neutrophils !!
What are granulocytes involved in
Innate immunity
How do neutrophils kill bacteria?
phagocytosis
engulf and destroy
granules contain lysosyme + myeloperoxidase.
ppl with too few neutrophils die of bac infection if not treated w antibiotics
where do neutrophils (type of granulocytes) live?
in blood for few hrs then migrate to tissues - cna live for 4-5 days
short. replaced
What do eosinophils do?
used in parasite infections (not phagocytic)
What do basophils do?
release histamine and heparin
hoe are eosinophils + basophils similar?
allergy/ atropy
What can monocytes do?
Migrate from blood into tissues and become macrophages
role in innate immnuity
how are monocytes similar to macrophages?
phagocytic
engulf+destroy dead cells, bacteria, protozoa, fungi
Where do T cells develop?
what are they and role?
T hymus
early progenitor for bone marrow but migrate and develop in thymus
what fo T cells exit thymus as?
naive cells - not yet exposed to antigen
where is thymus , role?
(gland behind sternum, in lungs - part of lymphatic system produces mature T cells)
what are (NK) lymphocytes?
small cells w low granularity (7-10 microM) by microscope
Where do B cells develop
Bone marrow
exit as naive cells
Where do Natural killer cells develop
bone marrow
what do T cells drive?
cell mediated immunity
what are dendritic cells
antigen presenting cells
work alongside T and B cells
What are mast cells
Cells that contain histamine, causes inflammation. Produced in the bone marrow but mature in tissues
allergy response
What is too few blood cells lead to?
Cytopenia
What is too many blood cells lead to?
Cytosis
normal values in blood of…
- red cells
- platelets
- neutrophils
- lymphocytes
red cells: 4.5-6.5 x 1012/L in M (lower in F)
… Hb more important 125 / 165 g/L
platelets: 150-400 x 109/L
neutrophils: 2.5-7.5 x 109/L
lymphocytes: 1.5-3.5 x 109/L
Describe the myeloid cells involvement in immunity.
granulocytes and monocytes
- neutrophils
live in blood for a few hours then migrate to tissues and live for 4-5 days
engulf and destroy bacteria (phagocytic)
granules contain lysosome and myeloperoxidase - eosinophils and basophils
both for allergy
eosinophils for parasite infections
less abundant - monocytes
migrate from blood into tissues and become macrophages
phagocytic; engulf and destory dead cells, bacteria, protozoa, fungi
Describe the two types of adaptive immunity.
humoral immunity: B cells = antigen specific antibodies
cell mediated immunity: T and NK cells = non specific
What is the lifespan of red cells, platelets, neutrophils and lymphocytes?
red cells: 120 days
neutrophils: <48 hours
platelets: 8-12 days
lymphocytes: years
whys chemotherapy done every 3 weeks?
as platelets and neutrophils are back at normal levels
lifespans:
neutrophils: <48 hours
platelets: 8-12 days
How long do eyrthrocyte transfusions, platelet transfusions and heamatopoietic stem cells last?
eyrthrocyte transfusions: 1 month - treatment of anaemia
platelet transfusions: few days
heamatopoietic stem cells: life long
What is haematopoiesis?
and When does haematopoiesis start?
blood cell production
starts 17 days after fertilisation and continues throughout life
regulated
What is leukaemia?
malignancies of haematopoietic cells arise in marrow and spread to involve blood/lymph nodes/spleen
4 types of haematologiccal malignancies?
leukaemias
lymphomas
myelomas
myeloproliferative disease + myelodysplasia
What is a lymphoma?
malignancies of lymphoid cells arise in lymph nodes/spleen and spread to involve blood and marrow
What is a myeloma?
malignancy of plasma cells (mature B lymphocytes) in marrow
can have multiple myeloma- multiple sites
What is myeloproliferative disease and myelodysplasia?
neoplastic chronic abnormal myeloid proliferation
maturation arrest causes what?
acute leukaemia
e.g. acute myeloid leukaemia (AML)
affects stem cells
proliferation of mature cells
when no maturation arrest –>?
over production of mature cells
e.g. chronic myeloid leukaemia (CML)
Classification of leukaemias
Lineage (Myeloid or lymphoid)
Maturation arrest or not: (acute or chronic)
Myeloid (AML or CML)
Lymphoid (ALL or CLL)
whys CLL (chronic lymphocytis leuk) different to all other leukaemias?
arises form mature cell (B lymphocytes)
What is a stem cell
cell that can differentiate and become any type of human cell
What are haemotopoietic stem cells (HSC)?
what about embryonic SC?
Multipotent
ESC = pluripotent can change to ANY cell in body
benefits of stem cell being able to divide indefinateky?
- can replenish itself
- give rise to specialised, differentiated cells
Where is the site of haematopoiesis in Infants
bone marrow
virtually all bones
Where is the site of haematopoiesis in adults
Bone marrow - axial skeleton
How to identify haemotopoetic cells
Cell markers
how is haematopiesis evaluated?
bone marrow biopsy - use local anaesthetci
hip bone surgery
in kids: sternum used
Name a condition in which monocyte cells will be elevated.
Allergy or Parasitic infection (Eosinophil).
What would a blood smear look like if theres no haematopoiesis?
hypocellular e.g. aplastic anaemia
no blood cells just fatty tissue
(trephine histology - best for cellularity)
How can you identify haematopoietic cells?
cell markers
CD (cluster of differentiation). standardised nomencalture (mainly leukocyte markers)
what does each hematopoietic cell have?
unique profile of markers (most names as CD)
diff functions - lineage / maturation/ function/ activation
whats immunophenotyping?
diff cells idnetified by diff monoclonal antibodies to cell markers
(usually by flow cytometry detecting fluorescent antibodies)
What do stem cells turn into?
mature blood cells
Where is the site of haematopoiesis in adults
Bone marrow - axial skeleton- skull + trunk
How can these haemotopiectic cells be identified
Monoclonal antibodies (immunophenotyping)
stem cells life
self renewal
or commitment…
maturation-> progenitor -> precursor -> mature
how is stem cell/ progenitor identified by?
functional assay
how is stem cell: precursor/ mature cell identified by?
routine marrow staining
how is stem cell at any stage of maturation identified ?
immunophenotyping
whats critical for haematopeiesis?
transcription factors
= proteins that control which genes turned on/off by binding to DNA + promoting/ blocking gene transcription
What effects do growth factors/cytokines have in hematopoiesis?
glycoproteins acting on specific receptors on haematopoeitic cells have multiple (pleiotropic) effects depending on cells
How can glycoproteins (G-CSF, a growth factor) affect haematopoesis
Proliferation Maturation Functional Activation Suppression of apoptosis
What are the key hormones in RBC and platelet production?
G-CSF
EPO
TPO (thrombopoeitin- platelet prodn)
whats EPO?
Erythropoetin (EPO)
HORMONE THAT STIMULATES RBC’S PRODUCTION
Growth factor in clinical use: G-CSF (2)
(recombinant SC injections) used for
- primary/ secondary preventions of infections in neutropenic patients (chemotherapy, congenital neutropenia)
- and to mobilise stem cells into periperal blood for stem cell harvest for stem cell transplants
whats is meant by
CSF
IL
colony stimulating factor
interleukin
How is erythropoiesis a negative feedback loop?
RBCs -> blood O2 content in lungs..
pO2 -> HIF-2 in kidney… EPO to erythroid precursors.
inc EPO = dec blood O2 content…
i.e. tissue oxygenation controls Epo production and Epo controls red blood cell (RBC) production, provides homeostasis in oxygen delivery to body tissues.
what in liver controls ion stores. and is inhibited by erythroferrone in epo loop?
hepcidin
What does a reticulocyte have and do?
has extruded nucleus but still has RNA.
can still make Hb (not possible in erythrocyte)
used to analsye causes of anemia
Growth factor in clinical use: EPO
(recombinant SC injections) used for imporvement of anaemia so transfusions not needed
mainly for end stage renal disease (endogenous epo low)
in what 3 particular cases is Growth factor in clinical use: EPO used?
some cases of myelodysplasia: low blood count
(when endogenous epo not increased)
patients getting chemotherapy
Jehovas witness (blood loss)- dont have blood transfusion
monocytes maturation stages by marrow staining…
monoblast -> promonocyte -> monocyte
whats neutropenia a side effect of and how treated?
chemotherapy,
prevented using recombinant G-CSF SC innjections
plateelts arise from what?
cytoplasm of megakaryocytes in bone marrow
2-3000 per megakaryocyte
platelet prodn is regulated by what?
TPO (thrombopoeitin)- hormone mainly produced by liver
Growth factor in clinical use: TPO .. receptor agonists
- romiplostim ( SC injections)
- eltrombopag (oral)
licensed for refractory immune thrombocytopenia (ITP) 2nd line
potential uses:
- thrombocytopenia in myelopdysplasia/post chemotherapy
- asplastic anaemia
what does blood consist of?
55% plasma (proteins, electrolytes, hormones, nutrients)
45% platelets, white cells + red cells
What is the function of RBC?
carry oxygen to tissues and return carbon dioxide from tissues to lungs
what is most of gaseous exchange in lungs + RBA acheived through?
Hb protein
in what stae can Hb bind to Oxygen?
Each haem group contains Fe which is reduced to Fe 2+. When it is in this state can bind to oxygen
what does one Hb protein mol consist of?
multi subunit protein (tetramer) made of 2 alpha, 2 bet subunits
heme:
one per unit
has Fe atom
carries 02
in RBC
whats anaemia?
Reduction in haemoglobin concentration, haemocrit or red blood cell count
What compensatory mechanisms occur during anaemia
- Increased oxygen extraction by tissues (vua 2, 3 DPG)
- Increased stroke volume and heart rate
Anaemia is classified as a reduction in the number of RBCs. What are the values that determine this in men and women?
in men below 130g/l and in women below 120g/l
the signs and symptoms of anaemia depend on the degree of anaemia and rate of development. What two things might anaemic patients experience?
decreased oxygen delivery to tissues and hypovolemia with acute bleeding
How might anaemic patients present? symptoms
Extetional dyspnoea Fatigue Palpitation Headache and drowsiness Angina and intermittent claudication
non-specific!
why are palpitations a symptom of anaemia?
heart has to work harder to pump blood around body
What might be the reason for anaemic patients experiencing headaches and drowsiness?
nutrient imbalances
List three things that can occur in anaemic patients as a result of volume depletion due to bleeding?
fatigue, muscle cramps and postural dizziness
What are the three main causes for anaemia in relation to red blood cells and blood?
reduced RBC production
increased RBC destruction
blood loss
Causes of reduced red cell production
- Lack of haemantinics (nutrients)iron, vit B12 and folate
- Bone marrow disorders
- Bone marrow suppression due to chemo
- Reduced EPO production in renal failure
- Anaemia of chronic disease
Causes of increased red cell destruction
- Inherited haemolytic anaemias
- Acquired haemolyic anaemia
Inherited haemolytic anaemias- 2 examples?
spherocytosis and sickle cell disease
Acquired haemolytic anaemias- examples?
coombs positive autoimmune
- warm and cold AIHA
What type of anaemia is caused by bone marrow disorders?
aplastic anaemia
Outline some of the reasons for increased destruction of RBCs?
- inherited such as spherocytosis or sickle cell
- accquired such as coombs antibodies
- reticulocytosis
What type of anaemia is it if mcv is low due to iron defiency?
microcytic
What type of anaemia is it if the mcv is high due to folate or b12 deficiency?
macrocytic
What is the term given to anaemia where the mcv is normal such as anaemia of chronic disease?
normocytic
What property of a red cell can determine the type of anaemia
Red cell size and shape
what does MCV tell you?
if anameia = micro/macro/normocytic
classification!
What cause of anaemia is most likely if MCV is normal and reticulocyte count is low?
anaemia of chronic disease such as renal or bone marrow failure
What cause of anaemia is most likely if MCV is normal and reticulocyte count is high?
hemolysis or blood loss
Calcium can conserve iron by recycling it from which cells?
senescent red blood cells
what do you measure with…
a) microcytic (low Hb)
b) macrocytic (high Hb)
a) Ferritin (establish cause if deficient)
b) B12 and folate
Loss of iron in men can be met by absorbing how much iron daily?
1-2mg
What is the daily requirement of iron required for erythropoesis?
20mg
total body iron
3000-4000mg
What is ferritin?
storage form of iron
Who is at risk of iron deficiency?
- infants who are premature or born to iron deficient mothers
- young women due to pregnancy and menstruation
- men and women with haemorrhoids due to GI blood loss
- children and adults with coeliac disease
treatment for iron deficiency anemia
iron supplements
What can anaemia of chronic disease cause
Mild microcytic or normocytic anaemia
in which type of anaemia may the blood ffilm show pencil cells?
iron deficiency
What would you expect the blood results of iron deficiency anaemia to reflect in terms of:
- MCV
- MCH
- WBC
- platelets
- Hb?
- low
- low
- normal
- normal or raised
- low
What do most hospitals use to assess iron status?
serum ferritin
transferrin saturation may be helpful in diagnosing iron defiency anaemia in which group of patients?
patients with cancer
Fe deficiency: total binding inc. saturation dec
iron deficiency anaemia can occur with normal or high Ferritin levels? T/F?
true
Why might ferritin levels be raised in liver dysfunction which may be the underlying reason for the anaemia?
ferritin is released by hepatocytes when damaged
Ferritin may be raised in patients where there is an increased haem turnover. Give 2 reasons why there may be an increased haem turnover in these patients?
haemolysis and trauma incl surgury
How long does a red blood cell live for
120 days
What is a reticulocyte?
immature RBC
What does the reticulocyte count show
The bone marrow’s response to anaemia
What are the signs of autoimmune haemolysis
Reticulocyte count raised at 350, Coombs test strongly positive, spleen enlarged
Treatment of autoimmune haemolysis
Prednisolone 1mg/kg with folic acid
What questions would you ask when taking the history of a patient with expected anaemia?
- Heavy menstrual loss, patterns, frequency and severity?
- taking aspirin?
- potential for Gi blood loss through haemorrhoids
- family history
- underlying genetic condition such as sickle cell
- any chronic disease such as rheumatoid?
- are there angular fissures or cheilosis around the mouth
- koilonychia?
- thin and underweight may suggest coeliac as an underlying cause
- ethnic origin
- evidence of chronic disease
Unless there is a clear indication otherwise what should be considered the cause of anaemia in young premenopausal women?
blood loss to due to menstruation
in a male with anaemia the patient should be referred to the GI unit for what two procedures?
endoscopy and colonscopy
Is there any clinical difference between ferrous fumarate, sulphate and gluconate which makes one of them a better pharmacological agent to treat iron deficiency anaemia?
no there is generally nothing to choose between them and they are equally efficacious
What side effects are very common with medication for iron deficiency anaemia such as ferrous sulphate, that you would want to make patients aware of?
GI intolerance, constipation, diarrhoea and nausea is very common with oral iron
Is it better to take iron on an empty stomach of after a meal?
better for absorption on an empty stomach but can be less tolerable so may be taken after a meal
What is the sufficient strength and dose of iron such as ferrous sulphate for most patients?
200mg 1-2 times daily
Why are slow release iron preparations illogical?
less iron be being absorbed from the preparation
What effect does alcohol and vitamin C have on the absorption of oral iron?
increases
What can be given to people to require iron who have a genuine oral intolerance?
IV such as cosmofer or ferrinject
Is anaemia of chronic disease macrocytic, microcytic or normocytic?
mild microytic and normocytic
anaemia of chronic disease caused/worsened by? (3)
malignancy, rheumatological diseases and chronic infection
What role do inflammatory cytokines play in anaemia of chronic disease?
cause reduced iron utilisation and impaired rbc production
Severity of anaemia of chronic disease reflects the disease activity and only improves upon one condition. What is this?
underlying disease is treated or controlled
What is the name given to the condition where red blood cells are destroyed faster than they are made?
haemolytic anaemia
whys it hard to distinguish between anaemua of chronic disease and early iron deficiency?
ferritin levels can be normal in both
or raised in A of CD or low in early ID
blood film in
a) anaemia of CD
b) early iron deficiency
a) normocytic, normochromatic
b) hypochromic, mild anisocytosis (diff shape + size
Which body structure can compensate for mild haemolytic anaemia but in severe cases survival is limited to only a few days?
bone marrow
The reticulocyte count reflects the bone marrows response to anaemia. What does a low reticulocyte count indicate and what does a high reticuloycte count indicate?
low means bone marrow hypoplasia and high means bone marrow is still responding
mild haemolysis is seen in…
thalassemia
and sickle cell disease
how may patients present with haemolytic anameia (autoimmune)?
pale and jaundices (bone marrow can tey and compensate for few days but may be severe case)
Autoimmune haemolytic anaemia is a serious potentially fatal condition unless treated quickly. What is the first line treatment for AIHA?
raised reticulocytes..
1mg/kg prednisolone and folic acid
What is second line treatment for AIHA?
azothioprine, myophencolate, ciclosporin or rituximab
Difficult cases of AIHA may require organ removal. Which surgury would these patients undergo?
splenectomy
List some things that can cause macrocytic anaemia?
- haematinic deficiency
- myleodysplasia
- liver disease
- haemolytic anaemia (reticulocytosis)
- hypothyroidism (macrocytosis not anaemia)
Macrocytic anaemia is commonly assoicated with b12 and folate deficiency, List some causes of these deficiencies?
- strict vegan diets
- autoimmine addisons pernicious anaemia
- GI (absorption) problems with terminal ileal problems such as chrohns or TB
How does Addisons pernicious anaemia lead to b12 deficiency?
antibodies are produced agaiinst intrinsic factor which is involved in b12 absorption
Where is the absorption site of
- vitamin b12
- folate
- terminal ileum
- duodenum and jejunum
Where is the mechanism of
- vitamin b12
- folate
- IF
- conversion to tetrahydrofolate
What are the therapeutic forms of
- vitamin b12
- folate
- hydroxycobalamin
- folic acid
Which type of anaemia may show neutrophil hypersegmentation in the blood film?
b12 or folate defiency
average daily intake of
- vitamin B12
- folate
- 5-30mcg
- 200-250mcg
dietary source of
- vitamin B12
- folate
- animal produce only
- greens, liver
minimum adult requirement intake of
- vitamin B12
- folate
- 1-2 mcg
- 150 mcg
body stores of
- vitamin B12
- folate
- 2-3mg (enough for few yrs)
- 10-12mcg (enough for few months)
What changes what you expect to see in the levels of MCV, WBC and platelets in macrocytic b12 or folate deficiency anaemia?
high mcv, normal or low wbc and normal or low platelets
to investigate macrocytic anaemia the levels of which two things should be checked as well as the function of one organ in the body?
measure b12 and folate levels and investigate thyroid function
what may blood film also show along w inc MCV, in B12/ folate deficiency?
neutrophil hypersegmentation
The blood film of a macrocytic anaemic patient may shown signs of mylodysplasia. These can be caused by certain drugs. Name the drugs that can cause this?
methotrexate, phenytoin, valproate and co triamaxozole
Explain how B12 is absorbed and uptaken in the body?
(not in slides) COBALAMIN
- present in meat and animal derived products
- b12 rapidly degraded by stomach acid and stabilised by complexing with haptocorrin (to prevent degradation)
- IF forms a complex with b12 in the duodenum which is alkaline and transported to the terminal ileum
- IF interacts with cubulin receptor and is taken into endosomes and degraded
- cobalamin attaches to lyosomal transporter which goes to vesicle forming complex with trans cobalamin 2
- transported in blood around the body
Which cells release IF and secrete HCl?
parietal cells
Which gland produces and secretes haptocorrin?
salivary glands
Where is the cubulin receptor located in the terminal ileum?
luminal surface of epithelial cells of terminal ileum
investigating macrocytic anaemia… steps?
- check B12 and folate levels
(most gPs measure thyroid function, but rare cause
wont usually think of haemolytic anaemias
blood films may show signs of myelodysplasia (or other marrow problem)
some drugs can cause macrocytosis
whats myelodysplasia?
treatment?
variety of clonal marrow abnormlaities, usually w macrocytic anaemia
many treated by reg transfusions but some respond to EPO
why must underlying cause be established with anaemia?
as its not a diagnosis, anaemia
B12 balance requires…
1-2 micrograms daily absorption
ssevere form of B12/ folate def?
pancytopenia
what can Fe deficiency without anaemia cause?
significant fatigue
serum ferritin + transferrin saturation (total Fe binding capacity) are affected by?
inflammation/ malignancy
Sources of Vitamin B12 (cobalamin)
- Meat
- Fish
- Dairy products
- Eggs
- Cheese
whats Haptocorrin?
produced by and role?
AKA: R-protein/ transcobalamin 1
• Produced by salivary glands
• B12 rapidly degraded by stomach acid
• Stabilised by complexing with haptocorrin
whats Intrinsic factor?
produced by and link with haptocorrin?
- Very similar structure
- Produced by gastric parietal cells
- Forms a complex with B12 in duodenum
- Vitamin B12 in stomach
- In acidic environment, B12 which is complexed to normal dietary proteins is released.
- To prevent degradation, forms complex with haptocorrin (purple C) for protection.
- Gastric parietal cells also then release intrinsic factor, a protein produced in the stomach (blue C)
- Complex moves to duodenum (alkaline environment) if pancreas normal functioning.
- Intrinsic factor and complex arrive
- New complex forms (swap)
• B12-IF complex remains stable until transported to terminal ileum. Last part of small bowel
2, Vitamin B12 absorption in terminal ileum:
- Cubilin receptor on luminal surface interacts with IF-Cbl complex and taken up into endosomes
- IF and Cbl separated
- IF degraded, Cbl attached to lysosomal transporter and sent to secretory vesicle. Forms complex with third protein: TC II. Transported uopt and distributed around body
summary of cobalamin lec
- B12 (cobalamin) from food
- Released from protein bay stomach acid binds to R-protein
- Released form R-protein by alkaline duodenum binds to Intrinsic factor
- Taken up by cubulin on cells in Terminal Ileum
summary of cobalamin lec
- B12 (cobalamin) from food
- Released from protein bay stomach acid binds to R-protein
- Released form R-protein by alkaline duodenum binds to Intrinsic factor
- B12 Taken up by cubulin on cells in Terminal Ileum
