10.1 Introduction to Haemopoiesis

Question 1

What is Haematopoiesis?

Answer 1

Formation of blood cells

Question 2

What are the two sections of haematopoiesis?

Answer 2

• Myelopoeisis: formation of cells in myeloid line
• Lymphopoiesis: formation of cells in lymphoid line

Question 3

What types of cells are in the myeloid line?

Answer 3

• Granulocytes
• Monocytes
• Erythrocytes
• Platelets

Question 4

What types of cells are in the lymphoid line?

Answer 4

• B cells
• T cells
• NK cells

Question 5

At what point do monocytes differentiate into other cells types? What are these cell types?

Answer 5

• Differentiate upon entering tissue
• Can become dendritic cells or macrophages

Question 6

Describe (and draw) the different outcomes of myelopoeisis

Answer 6

• Haematopoietic stem cells differentiate into myeloid progenitor
• Then, can become either:
• Megakaryocyte (platelet)
• Granulocytes (basophil, eosinophil, neutrophil)
• Erythroblast (erythrocyte)
• Monocyte

Question 7

Describe (and draw) the different outcomes of lymphopoiesis

Answer 7

• Haematopoietic stem cell becomes common lymphoid progenitor
• Differentiates into B or T precursor -> cell, or NK cell

Question 8

Are haematopoietic stem cells pluripotent or multipotent? What are the implications of this?

Answer 8

• They are pluripotent
• They can become non-blood cells when required

Question 9

Are progenitor cells pluripotent or multipotent?

Answer 9

Mutlipotent (can only make myeloid OR lymphoid)

Question 10

List the different sites of haematopoiesis throughout life

Answer 10

• Starts in yolk sac and then liver
• From 3-7 months: spleen
• 7 months onward: bone marrow
• Continues in bone marrow throughout adult life, albeit decreasing

Question 11

What is the most common leukocyte?

Answer 11

Neutrophils

Question 12

Blood conditions that end in “penia”; what does this indicate?

Answer 12

Low production (e.g. leukopenia)

Question 13

Blood conditions that end in “cytosis” or “philia”; what does this indicate?

Answer 13

Overproduction (e.g. basophilia)

Question 14

Lifespan of neutrophils? Also, describe their nuclei

Answer 14

Lifespan: 2.5 days
Nucleus: multilobed

Question 15

Describe the nucleus, lifespan, and proportion of leukocytes of eosinophils

Answer 15

• Bi-lobed (dumbell)
• Lifespan: 7-12 days
• Proportion: 1-3%

Question 16

Lifespan/WBC proportion of monocytes

Answer 16

• Lifespan: 2-5 days
• Make up 1-6% of circulating WBCs

Question 17

What dye do eosinophils take up?

Answer 17

Eosin

Question 18

Lifespan of basophils, WBC proportion, and what do their granules contain?

Answer 18

• Lifespan: 12-15 days
• <1% of circulating WBCs
• Granules contain inflammatory mediators: histamine, prostaglandin

Question 19

Basophil function

Answer 19

Initiation of inflammation

Question 20

Colour of granules in basophils and mast cells?

Answer 20

Blue

Question 21

Difference in location between mast cells and basophils?

Answer 21

Mast cells: In tissues
Basophils: in blood

Question 22

Are B and T cells morphologically distinct?

Answer 22

No. The only difference is what they express in their cell surface

Question 23

What are the second most common leukocytes in the blood?

Answer 23

Lymphocytes

Question 24

At what point does a CD4 T cell become a T helper cell?

Answer 24

When it starts releasing cytokines

Question 25

What influences what kind of T helper cell is produced from a CD4 T cell?

Answer 25

Which cytokines it releases

Question 26

How do we identify specific kinds of leukocytes in a stain?

Answer 26

By using cell surface markers

Question 27

What are the primary lymphoid organs? What occurs in them?

Answer 27

- They are the bone marrow and the thymus - B and T cells gain their receptors - They undergo education, and are released into the bloodstream

Question 28

What occurs in secondary lymphoid organs?

Answer 28

- B and T cells encounter antigen - They then differentiate into effector cells

Question 29

What are the secondary lymphoid organs?

Answer 29

- Lymph nodes - Spleen

Question 30

Describe the transport of lymphocytes around the body in search of their antigen

Answer 30

- Go to 2° lymphoid organ - Wait for a while - If not there, back into blood, and to another lymphoid site

Question 31

What cells are in the follicles of a lymph node's cortex?

Answer 31

B cells

Question 32

What cells are in the paracortex of a lymph node?

Answer 32

T cells

Question 33

What separates medullary sinuses in a lymph node? What do they contain?

Answer 33

- Medullary cords - They contain plasma cells

Question 34

How are antibodies released from lymph nodes into circulation?

Answer 34

Plasma cells in medullary cords release antibodies into medullary sinuses, which leave via afferent lymphatics

Question 35

Describe the action of a follicular dendritic cell. Why is this useful for B cells?

Answer 35

- Grabs onto antigen, and doesn't let go - This is useful, since B cells cannot take antigens that have been chopped up