Haematopoiesis Flashcards
What is haematopoiesis
It is the production of circulating blood cells from the bone marrow
Life span of granulocytes
<48hrs
Concentration of granulocytes in the blood
2-8x10^9
Life span of erythrocytes
120 days
Concentration in the blood
5x10^12/L
Life span of platelets
7-10days
Concentration of platelets
150-450x10^9/L
Lifespan of monocytes
Days to weeks depending on differentiation. Some tissue macrophages may last years
Concentration of macrophages in the blood
0.5x10^9/L
Lifespan of lymphocytes
Days to years depending on whether naive or memory
Concentration of lymphocytes
1-4x10/L
What is immunophenotyping
Look for specific markers or proteins found on the cell surface or inside the cell DNA be performed on blood or bone marrow looking for a specific cell type
What does the marker CD34 identify and why is it used
It identifies a subset of marrow cells including HSCs only small numbers are usually present in the blood but the number is increased when recovering from damage inflicted by cytotoxic drugs following administration of G-CSF for stem cell harvesting for transplant
Helps to identify these cells
Where does haematopoiesis occur in the fetus
Extra embryonic yolk sac
Aorta-gonad-mesonsephros
Liver
Bone marrow
What day does haematopoiesis start in the fetus
Day 17
Where does haematopoiesis occur in the adult
Bone marrow Red and yellow marrow Active bone marrow is in the red marrow Yellow marrow is adipocytes The marrow is found in the medullary cavity - space enclosed by the cortex and traversed by trabeculae
When can haematopoiesis occur in other sites a d what sites are those
Liver and spleen
Condition called extra medullary haematopoiesis occurs in certain pathologies myelofibrosis or untreated thalassaemia
Cell fate choices of a HSC in haematopoiesis
Quiescence, self renewal, differentiation
Progenitor cell fate choices
Proliferation, lineage commitment, terminal differentiation
What doe progenitor cells require in order to differentiate into their terminal cell
Intrinsic factors- lineage determining TF and their epigenetic regulation
Extrinsic regulators - both cellular an soluble growth factors found in the bone marrow micro environment. These factors are up and down regulated according to certain stimuli.
Where can the cellular elements be found
Bone marrow stroma
- surrounding bone, network of vascular channels and sinusoids, fat cells, fibrocytes, and extracellular Maria
Bone marrow testing samples are taken from where
Iliac crest
What types of assessment of haematopoiesis are there and what do they assess
Bone marrow trephine
Core of BM and is used to examine the overall cellularity and architecture of bone marrow and ECM components
Bone marrow aspirate used to assess morphology/numbers of HSC at different t stages and identify abnormal infiltrates
What is the commonly used term for early progenitor cells
Blast
Platelet progenitor cells
Megakaryoblast
Megakaryocyte
What is platelet production regulated by
TPO
Throbopoietin
Produced by the liver
In what instances are platelets transfused and how long do they last
Chemotherapy
1-5 days
When is it futile to infuse platelets
Immune Thrombocytopenia
Only last few hours due to ab against them and spleen clearance
What regulates granulocytes and monocytes production
G-CSF
GM-CSF
What are precursors names for granulocytes and monocytes
Promyelocytes
Promonocytes
They have identifiable lineage specific granules that stain - MPO for neutrophil lineage
At the granulocyctic lineage myelocyte stage cells acquire distinctive lysosomal enzymes and other granules required for function
Mature granulocytes features
Lost chromaitn
Segmented nuclei
Cannot proliferate
Monocytes features
Retains potential to divide but it appears usual
What regulates erythrocytes
EPO
From kidneys
Nutritional factors and co factors required fro erythropoiesis
Iron B12 Folate B6 C E Cobalt Manganese Amino acids
Eosinophils factor
IL5
Lymphoid cell line factor
IL7
Hb made up of
Porphyrin haem 4poly peptide chains
