10.1 Introduction to Haemopoiesis Flashcards
What is Haematopoiesis?
Formation of blood cells
What are the two sections of haematopoiesis?
- Myelopoeisis: formation of cells in myeloid line
- Lymphopoiesis: formation of cells in lymphoid line
What types of cells are in the myeloid line?
- Granulocytes
- Monocytes
- Erythrocytes
- Platelets
What types of cells are in the lymphoid line?
- B cells
- T cells
- NK cells
At what point do monocytes differentiate into other cells types? What are these cell types?
- Differentiate upon entering tissue
- Can become dendritic cells or macrophages
Describe (and draw) the different outcomes of myelopoeisis
- Haematopoietic stem cells differentiate into myeloid progenitor
- Then, can become either:
- Megakaryocyte (platelet)
- Granulocytes (basophil, eosinophil, neutrophil)
- Erythroblast (erythrocyte)
- Monocyte
Describe (and draw) the different outcomes of lymphopoiesis
- Haematopoietic stem cell becomes common lymphoid progenitor
- Differentiates into B or T precursor -> cell, or NK cell
Are haematopoietic stem cells pluripotent or multipotent? What are the implications of this?
- They are pluripotent
- They can become non-blood cells when required
Are progenitor cells pluripotent or multipotent?
Mutlipotent (can only make myeloid OR lymphoid)
List the different sites of haematopoiesis throughout life
- 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
What is the most common leukocyte?
Neutrophils
Blood conditions that end in “penia”; what does this indicate?
Low production (e.g. leukopenia)
Blood conditions that end in “cytosis” or “philia”; what does this indicate?
Overproduction (e.g. basophilia)
Lifespan of neutrophils? Also, describe their nuclei
Lifespan: 2.5 days
Nucleus: multilobed
Describe the nucleus, lifespan, and proportion of leukocytes of eosinophils
- Bi-lobed (dumbell)
- Lifespan: 7-12 days
- Proportion: 1-3%
Lifespan/WBC proportion of monocytes
- Lifespan: 2-5 days
- Make up 1-6% of circulating WBCs
What dye do eosinophils take up?
Eosin
Lifespan of basophils, WBC proportion, and what do their granules contain?
- Lifespan: 12-15 days
- <1% of circulating WBCs
- Granules contain inflammatory mediators: histamine, prostaglandin
Basophil function
Initiation of inflammation
Colour of granules in basophils and mast cells?
Blue
Difference in location between mast cells and basophils?
Mast cells: In tissues
Basophils: in blood
Are B and T cells morphologically distinct?
No. The only difference is what they express in their cell surface
What are the second most common leukocytes in the blood?
Lymphocytes
At what point does a CD4 T cell become a T helper cell?
When it starts releasing cytokines
What influences what kind of T helper cell is produced from a CD4 T cell?
Which cytokines it releases
How do we identify specific kinds of leukocytes in a stain?
By using cell surface markers
What are the primary lymphoid organs? What occurs in them?
- They are the bone marrow and the thymus
- B and T cells gain their receptors
- They undergo education, and are released into the bloodstream
What occurs in secondary lymphoid organs?
- B and T cells encounter antigen
- They then differentiate into effector cells
What are the secondary lymphoid organs?
- Lymph nodes
- Spleen
Describe the transport of lymphocytes around the body in search of their antigen
- Go to 2° lymphoid organ
- Wait for a while
- If not there, back into blood, and to another lymphoid site
What cells are in the follicles of a lymph node’s cortex?
B cells
What cells are in the paracortex of a lymph node?
T cells
What separates medullary sinuses in a lymph node? What do they contain?
- Medullary cords
- They contain plasma cells
How are antibodies released from lymph nodes into circulation?
Plasma cells in medullary cords release antibodies into medullary sinuses, which leave via afferent lymphatics
Describe the action of a follicular dendritic cell. Why is this useful for B cells?
- Grabs onto antigen, and doesn’t let go
- This is useful, since B cells cannot take antigens that have been chopped up
