Myelopoiesis and Lymphopoiesis I Flashcards
What are some of the important things to remember from this hematologic lineage flow chart?
- All the recognizable precursors end with ‘blast’
- Cell division only occurs in multipotent stem cells, committed stem cells and recognizable precursors i.e’in the top half of the chart’
- These actively dividing cells are morphologically identical, only maturing and mature myeloid cells can be recognized based on their appearence.
- All the myeloid stem cells have limited life span, whereas the lymphoid cells can survive for many years and they can divide at any phase of cell cycle, even during the mature phase.
- All hematologic neoplasms originate from dividing cells, hence the cells in the top half of the chart.
What are the different growth factors involved in cell maturation and development?
What are the sites of hematopoiesis from prenatal life to adulthood?
Yolk sac: 3 weeksMesoderm of intraembryonic aorta, gonads, mesonephros region: 3 weeks to 3 monthsLiver: 3 months to birthBone marrow: 4 month to death
How does hematopoiesis change with age?
Shifts to flat bones of axial skeleton, most common location to do a bone marrow biopsy is from the iliac crest of an adult or sometimes it can be done at the sternum
What is extramedullary hematopoiesis?
When the demand of hematopoiesis is high and the bone marrow can not keep up there is reactivation of hematopoiesis outside the bone marrow such as in liver, spleen, lymph nodes etcThe most common reason for this is hemolytic anemia or neoplasm
What are the different components of bone marrow?
Sinusoids, hematopoietic cells and fat.It is important to know that the blood is not continuous with the hematopoietic space.
What is the myeloid:erythrocyte normal ratio in the bone marrow?
3:1 in favor of Myeloid cells, which makes sense as myeloid cells like neutrophils have a life span max of 5 days, so there is a greater turnover
What cells are classified as granulocytes?
Neutrophils, basophils and eosinophils, primary function of these cells is phagocytosis
Explain the steps of Neutrophil development starting from Myeloblast.
Don’t need to know the names but it is important to know the morphological changes that occur during different stages of development
Explain the steps of erythroid maturation starting from Proerythroblast.How does RBCs get rid of their nucleus?
Via pyknosis and ‘removal’ of the remaining nucleus
What are the different components of blood?
Explain the phenomena of left shift.What is the significance of toxic granulationand Dohle bodies?
- Left shift refers to increased circulation of band neutrophils or even further stages of immature neutrophils that can be seen on a blood smear.
- Left shift is almost always induced by an inflammatory process
- Toxic granulations and Dohle bodies are morphological changes that are seen on neutrophils in left shift
- Presence of toxic granulations and Dohle bodies signifies the fact that the increase in neutrophils is due to an inflammatory etiology instead of a neoplastic etiology
Define Leukemoid reaction.
- Leukemoid reaction – marked granulocytosis and left shift, resembling chronic myeloid leukemia (CML)
- Reactive morphology (toxic granulation and Döhle bodies are seen)
- To rule out CML we have to genetically look for Philedelphia chromosome
Define Leukoerythroblastocytosis.
Defined by left shift and circulating nucleated red blood cells (remember that the only RBCs in circulation are reticulocytes and mature RBCs, both lack a nucleus).This signifies:
- Bone marrow fibrosis
- Bone marrow infiltration - can be infectious or neoplastic
What are the functions of eosinophils?What does their granules contain?
Anti parasitic function, allergic reactions and chronic inflammation.Granules contain
* Peroxidase
* Major basic protein
* Eosinophilic cationic protein
* Eosinophil derived neurotoxin
Last 3 are cytotoxic for helminths and protozoas
