Haemopoiesis Flashcards
What white cells modulate hypersensitivity rxns?
Eosinophils and Basophils
Which cell destroys parasites?
eosinophils
What are the diff. types of lymphocytes?
B-cells (Abs)
Tcells
NK cellls (anti-viral/ tumor)
What do monocytes convert to in the tissues?
Macrophages
What may be present in high no.s with acute inflammation?
Neutrophils
What do macrophages do?
phagocytic clearance
What is the lifespan of neutrophils?
7-10 days
1 mill. platelets are made/ sec
What is a myelocyte?
nucleated precursor between neutrophils and blasts
What do all “blast” cells have in common?
they are NUCLEATED (erythroblast/ myeloblast)
Name the immediate red cell precursor.
Reticulocytes (polychromasia)
Name the platelet precursor.
megakaryocytes (polypoid)
Where do these progenitor/precursor cells come from?
HAEMOPOIETIC STEM CELLS
What do the multipotent progenitor cells give rise to ?
Myeloid progenitor
Lymphoid progenitor
What particular cell can self-renew?
stem cells
ft lost in following descendents
What is seen with differentiation in haemopoiesis?
—–What may occur simultaneously with differentiation?
- stem cell descendants commit to ONE or MORE lineages
- proliferation (which may also occur simultaneously with maturation)
What happens in maturation of descendant cell?
- descendants acquire FUNCTIONAL properties and may stop proliferating
Where do haemopoietic stem cells originate embryonically?
- from the MESODERM
Where is the first site of erythroid acitivity in an embryo?
YOLK SAC
stops by week 10
What picks up on haemopoiesis, after the yolk sac and when?
- at week 6, LIVER starts
–by week 16, Bone marrow starts
Where does haemopoiesis occur in the marrow?
- in AXIAL skeleton (best)
- PELVIS
- PROXIMAL LONG bones
Haemopoiesis of the TIBIA and FEMUR drastically falls by what age?
tibia: by 20 y.o
femur: by 25 y.o
- —-so NOT the best place to obtain bone marrow sample retrieval
Best place for bone marrow biopsy?
- iliac crest
- Sternum
Where is bone marrow biopsy obtained from in a bby?
- anterior tibia
What is seen under the microscope of a bone marrow sample?
- cellular: Haemopoietic cells and Non hemopoietic cells
- Connective tissue matrix
- Vascular elements
What are non-haemopoietic cells like?
- adipocytes
- fibroblasts
- osteoclasts/ osteoblasts
Describe the relation between arteriole and venou sinsuses in the bone marrow vasculature.
- arterioles DRAIN into sinuses (wide venous vessels> open into LARGER central sinuses)
- —SINUSES are radially distributed around the draining CENTRAL sinus
What is the diff. between vein and sinuses?
—-sinuses are larger and have a DISCONTINUOUS BM
How do formed blood cells make its way into the circulation?
-the blood cells pass through the fenestrations in the endothelial cells of the sinusoids
WHat is the release of red cells associated with?
- sinusoidal dilatation and INCR. blood flow
Why are there fewer choices for bone marrow sampling retrieval in older people?
(can’t retrieve from proximal long bones at old age)
—d.t INCR. in YELLOW marrow (Fatty, inactive marrow) with AGE
vs LOSS of red (haemopoietically active) marrow.
What is the myeloid: erythroid ratio?
- ratio of myeloid to erythroid PRECURSORS to the bone marrow
(1. 5:1)–> (3.3:1)
When may myeloid : erythroid ratio reverse?
in hemolysis
- as a compensatory response
What regulates haemopoiesis?
- Intrinsic propert. of cells
- Signals from immediate surroundings and the periphery (MICROENV. factor)
- specific anatomical area (NICHE) for optimal developmental signals
What regulates neutrophil precursor maturation?
G-CSF
granulocyte - colony stimulating factor
WHat regulates the growth and development of megakaryocytes from their precursors?
Thrombopoietin
What microenvironmental regulation exists for haemopoiesis?
- haem-poietic stem cells OCCUPY a NICHE (anatomical site) —-that provides signals for expansion/ differentiation or dormancy
- —site: around arteriole/ sinusoid; provides access to diff. signals (cytokines)
—-site is ALTERED in disease/ therapy
How to assess haemopoiesis?
- Blood count/ cell indices/ morphology
2. Less common: BONE marrow examination—-usually to see precursor cell acitivity
What test are sufficient for NON-lymphoid cells?
- bloood count
- morphological assessment
How to assess lymphoid cells?
- the expression of antigens (indicate lineage/ stage development)
by immunophenotyping
What does immunophenotyping curtail?
- way to IDENTIFY patterns of protein expression UNIQUE to a celll lineage
- —Ag expression study done with specific Abs =
How do you recognize diff. lymphocyte subsets?
- monoclonal Abs SPECIFIC for each marker (anti- CD45/ CD3/CD4 Etc)
- -which are covalently labelled with fluorrescent dyes —-each Ab will cause cells that it recognises to FLUORESCE with a unique color
How do you quantify the fluorescent findings of lymphocyte sybsets?
- —-pt sample that is stained with fluorescent monoclonal Abs in the Trucount tube (containing the Trucount beads)
- is then run through the Flow cyotmeter together with the Trucount beads
–allowing calculation of the absolute Value of cell no. for each subset
