Haemopoiesis

Question 1

What is haemopoiesis

Answer 1

The formation of blood cells

Question 2

Name the three types of mature blood cells

Answer 2

Red cells (erythrocytes)
Platelets (thrombocytes)
White cells (leukocytes)

Question 3

State the two blood cells that don’t have a nucleus

Answer 3

RBCs (erythrocytes)
Platelets (thrombocytes)

Question 4

Name the three sub types of leukocytes

Answer 4

Granulocytes
Monocytes/macrophages
Lymphocytes

Question 5

Name the three white cell granulocytes and state their function

Answer 5

Neutrophils (phagocytosis/acute inflammation)
Eosinophils (parasites, hypersensitivity)
Basophils (hypersensitivity)

Question 6

State the 2 main function of monocytes/macrophages

Answer 6

They modulate immune reactions
They are involved in Phagocytic clearance

Question 7

Name the three types of lymphocytes and state their function

Answer 7

B cells (humoral immunity)
T cells (cell-mediated immunity)
NK cells (anti-viral/tumour)

Question 8

Red cell lifespan

Answer 8

120 days

Question 9

Neutrophil lifespan

Answer 9

7-8 hours

Question 10

Platelets lifespan

Answer 10

7-10 days

Question 11

If a cells name ends in -blast, what does this mean?

Answer 11

It is a nucleated precursor cell

Question 12

State the name for RBC, platelet & neutrophil precursors

Answer 12

Erythrocyte - (erythroblast & then) Reticulocyte
Platelet - Megakaryocyte
Neutrophil - (myeloblast & then) Myelocyte

Question 13

What can form from a myeloid precursor cell

Answer 13

Erythrocytes
Thrombocytes
Granulocytes (neutrophils/basophils/eosinophils)
Monocytes/macrophages

(+ dendritic cells)

Question 14

What can form from a lymphoid precursor cell

Answer 14

Lymphocytes
- T cells
- B cells/ plasma cells
- NK cells

(+ Dendritic cells)

Question 15

What is self renewal & what cell type has this property

Answer 15

Every time a stem cell divides it produces one cell that is exactly like its self (self renewal) & one cell that is not

HSC can self renew, progenitor cells cant

Question 16

Proliferation vs differentiation vs maturation

Answer 16

• Proliferation - Increase in numbers
• Differentiation - Descendants commit to one or more lineages
• Maturation - Descendants acquire functional properties & may stop proliferating

Question 17

Haemopoietic stem cell vs progenitor cells vs precursor cells

Answer 17

• HSC - can self renew & differentiate into any blood cell type
• Progenitor cell type - can differentiate into multiple blood cell types
• Precursor cells (aka blast cells) - can only differentiate into one cell type

Question 18

What are the three different meanings of the term ‘myeloid’

Answer 18

‘Marrow’ e.g. myeloid malignancy
‘Non-lymphoid lineage’ e.g. myeloid lineage
‘Granulocyte’ e.g. myeloid:erythroid ratio

Question 19

Red vs yellow marrow

Answer 19

Red marrow - haemopoietically active
Yellow marrow - fatty & inactive

Question 20

Where do HSCs originate from embryonically

Answer 20

The mesoderm

Question 21

Where is the first site of erythroid activity and how long does this last for?

Answer 21

Yolk sac (stops by week 10)

Question 22

When does haemopoiesis start in the liver

Answer 22

By week 6

Question 23

When does haemopoiesis start in the bone marrow

Answer 23

By week 16

Question 24

Where does haemopoiesis occur in an adult

Answer 24

Bone marrow of axial skeleton, pelvis, & proximal long bones

Question 25

When does haemopoiesis start in the spleen

Answer 25

By week 10

Question 26

Where would you take a bone marrow biopsy from in an adult vs child (less than 18 months)

Answer 26

Adult - Posterior superior iliac spine (PSIS) Child (less than 18 months) - Leg bone e.g. tibia

Question 27

Describe the structure of a bone marrow venous sinuses & explain its relevance

Answer 27

- fenestrated endothelium & - discontinuous basement membranes - allows blood cells to enter the circulation

Question 28

Describe the structure (4 components) of bone marrow

Answer 28

- Connective tissue - Vascular elements (periosteal artery network & sinusoids) - Haemopoietic cells - Other cells (adipocytes, fibroblasts, osteoblasts/clasts)

Question 29

Where do blood cells pass through in the bone marrow in order to enter circulation

Answer 29

Fenestrations in endothelial cells of sinusoids

Question 30

What changes in the sinusoids are associated with RBC release

Answer 30

Sinusoidal dilatation & Increased blood flow

Question 31

How are thrombocytes released into sinusoidal blood vessels

Answer 31

Through proplatelets (long branching processes of megakaryocytes that connect to the sinusoids)

Question 32

What is the myeloid:erythroid ratio

Answer 32

The M:E ratio indicates the relative numbers of myeloid lineage cells (all granulocytic and monocytic cells) to nucleated erythroid precursors in marrow

Question 33

What are the three main factors that regulate haemopoiesis

Answer 33

Intrinsic properties of cells (e.g stem cells vs progenitor cells vs mature cells) Signals from immediate surroundings and the periphery (microenvironmental factors) Specific anatomical area (‘niche’) for optimal developmental signals

Question 34

What signalling molecule regulates RBC, neutrophil & platelet production

Answer 34

Erythrocytes - erythropoietin Neutrophils - granulocyte-colony stimulating factor (G-CSF) Platelets - thrombopoietin

Question 35

Describe eosinophil, neutrophil, monocyte & lymphocyte morphology

Answer 35

- Eosinophils - tomatoes with sunglasses - Neutrophil - multi lobed nucleus, granulocytes - Monocytes - big chunky cell, single lobed, kidney bean nucleus, ‘ground glass’ cytoplasm - Lymphocyte - large purple nucleus

Question 36

What investigations are used to assess haemopoiesis of non-lymphoid mature cells

Answer 36

MORPHOLOGY! - First line - FBC, cell indices & blood film - Specialist test - bone marrow examination

Question 37

What investigations are used to assess haemopoiesis of lymphoid mature cells and why is it different from non-lymphoid mature cells

Answer 37

- Immunophenotyping - Not blood film as the different lymphoid lineages (& HSCs & progenitors & myeloblasts) are all morphologically similar

Question 38

How does immunophenotyping work

Answer 38

Identify patterns of protein (antigen) expression unique to a cell lineage Use antibodies (in combination) specific to different antigens

Question 39

What is the name of the process that produces erythrocytes

Answer 39

Erythropoiesis

Question 40

What is the name of the process that produces thrombocytes

Answer 40

Thrombopoiesis

Question 41

What is the name of the process that produces granulocytes

Answer 41

Myelopoiesis OR granulopoiesis

Question 42

What is the name of the process that produces monocytes

Answer 42

Monocytopoiesis

Question 43

What is the name of the process that produces lymphocytes

Answer 43

Lymphopoiesis

Question 44

Haemopoietic stem cells & progenitor cells are based mainly in the bone marrow in adults. Where would you expect a higher proportion of HSCs in blood than normal

Answer 44

Umbilical cord blood

Question 45

Where in the bone marrow do macrophage develop

Answer 45

Erythroid islands

Question 46

What happens to the myeloid:erythroid ratio in acute blood loss

Answer 46

Decreases

Question 47

What happens to the myeloid:erythroid ratio in haemolysis

Answer 47

Decreases

Question 48

What happens to the myeloid:erythroid ratio in post pneumonic empyema

Answer 48

Increases

Question 49

What happens to the myeloid:erythroid ratio in post pneumonic empyema

Answer 49

Increase

Question 50

Why is morphology not useful for identifying haemopoietic progenitors and/or stem cells? What technique is helpful to assign lineage to cells when morphology is unreliable?

Answer 50

HSCs & progenitors & myeloblasts & lymphocytes have similar morphology Immunophenotyping is used instead

Question 51

Other than bone marrow, where are sinusoids found

Answer 51

Liver & spleen

Question 52

Immunophenotyping vs immunohistochemistry

Question 53

Why is bone marrow biopsy not indicated in situations where the change in blood count is reactive?