Hematopoiesis Flashcards
What does myeloid tissue mean?
Tissue that is related to the bone marrow
What is lymphoid tissue?
Tissue that is related to the lymphatic system (lymph nodes, thymus, spleen)
Within the bone marrow, progenitor cells either belong to the ____ or ____ family lineage
Myeloid
Lymphatic
Which cells arise from myeloid lineage?
Granulocytes, monocytes, erythroids, megakaryocytes/platelets
Which cells arise from lymphoid lineage?
Lymphocytes and plasma cells
How does maturation of lympohid cells differe from myeloid cells?
Myeloid cells mature in peripheral blood, lymphoid cells mature in lymphoid tissues before entering peripheral blood
Within the myeloid lineage of bone marrow HSC, how are the types of cells further divided?
Into series
- myeloid series (granulocytes)
- Monocytic series (monocytes)
- Erythroid series (erythrocytes)
- Megakaryocytic series (platelets)
What is a normal ratio of #myeloids : #erythroids?
2 or 3 : 1
What is the myeloid organ?
bone marrow
What is the difference between bone marrow core biopsy and bone marrow aspirate?
Aspirate does not contain any bone spicules, taken by aspirating bone marrow using 11G needle.
- Other than hematopoetic stem cells, what other class of stem cells are in bone marrow?
- What effect do MSCs have on HSCs?
- Mesenchymal stem cells that ultimately become Bome Marrow Stromal Cells (chondrocytes, osteoblasts, adipocytes, endothelial cells. etc)
- They influence HSC behavior
Are most stem cells quiescent or actively dividing?
Quiescent
Once an HSC has been activated, what 3 outcomes are available to it?
Apoptosis
Self-renewal (proliferation)
Differentiation (progenitor for myeloid or lymphoid)
What signals drive an HSC to become a myeloid progenitor cell?
SCF
TPO
What signal drives an HSC to become a lymphoid progenitor cell?
Interleukin - 7
What affect does injury have on HSCs in bone marrow?
It results in a shift towards differentiation to generate more progenitors to keep up with homeostasis
What signaling molecule promotes differentiation from a myeloid progenitor to megakaryocytes-erythroid precursor?
IL-3
What signaling molecule promotes megakaryocyte-erythroid precursor to become platelet? To become erythrocyte?
Platelet - TPO
Erythrocyte - EPO
Describe how RBCs appear during staining from early differentiation to late differentiation.
More blue at beginning, more orange at end due to increased presence of Hb
_____ are the largest cells in the marrow
Megakaryocytes
Megakaryocytes have _____ nuclei
Many (multinucleate)
Describe how platelets are made
Megakaryocyte produces pseudopods that are anuclear fragments. However these are very active, with receptors and intracellular signaling molecules. These pseudopods become platelets.
EPO is constitutively produced in the _____ and inducible in the _____
Liver
Kidneys
G-CSF is a glycoprotein that stimulates the bone marrow to produce granulocytes and release them into the bloodstream. Describe how the body goes about secreting G-CSF.
It is inducible in macrophages, fibroblasts, and endothelial cells by inflammatory signals
- TPO (thrombopoeitin) is constitutively produced in the ______ and ______ and is inducible in the ______ and _____ by response to ______.
- The major regulator of TPO production is _____
- Liver and kidneys
- Liver and bone marrow, IL-6
- Platelet count
c-MpI is a receptor on platelets that binds to TPO in the blood. How does [platelets] regulate their own production through this receptor interaction?
When TPO binds to c-MpI on platelet, then that TPO is destroyed by the platelet. As such, it does not travel to bone marrow and does not stimulate megakaryocyte to produce more platelets. So when there are plenty of platelets, they regulate their own production in this manner. When platelet count is low, then the TPO is able to travel to the marrow and activate megakaryocytes.
What signaling molecule stimulates differentiation into a monocyte?
Into a granulocyte?
M-CSF
IL-5
For lympoid tissues:
- IL-2 induces formation of ____
- IL-4 induces formation of _____
- IL-15 induces formation of ____
- T-cells (2T Frutti –>2T –> T cells)
- B-cells (Before –> B4 –> B cells)
- NK-cells
Differentiation of an HSC into CMP or CLP results in loss of __________
self-renewal
Cells in the myeloid lineage of bone marrow can be subdivided into 3 categories: Graulocytic, erythroid, and megakaryotic cells.
The most primitive cell that will ultimately become granulocytes is called a blast. Describe the process of maturation from a blast to a neutrophil, eosinophil, basophil.
The blast:
- Decreases in cell size,
- Decreases in cytoplasmic basophilia (meaning decrease in polyribosomes)
- Increases in cytoplasmic granules
- Increase in lobulation of the nucleus
The granules that distinguish neutrophil, eosinophil and basophil become specific become specific about half way through this process.
Bands are the last common cell to neutrophils, eosinophils and basophils.
What does it indicate if a person has a lot of bands in their peripheral blood?
Bands are immature granulocytes, so a large number of them in the blood would indicate that the body is rapidly mobilizing cells of the innate immune system in an effort to fight off an infection.
Describe the process of maturation of an erythroid.
Erythroblast –> normoblast –> reticulocyte –> RBC
As the cels progress through these phases they undergo:
- Cells become less blue
- Decreased cytoplasmic volume
- Decreased nuclear size
- Increased nuclear density
- Loss of nucleus
What is the difference between a reticulocyte and an erythrocyte?
Reticulocytes are the last progenitor cell of erythrocytes in the bone marrow. They are anucleate. During RBC maturation in the bone marrow, the cell would have synthesized all the Hb that it will need for its lifetime and acquired sufficient iron for its lifetime use. As the erythrocyte circulates it assembles Hb as needed for O2 transport. Failure to acquire enough Iron during maturation leads to cell death and anemia.
B cells mature in the ______
T cells mature in the ______
Bone marrow
Thymus
