1. Hematopoiesis Flashcards
what are the 8 types of cells we will typically see in a smear?
neutrophil (mature), neutrophil (immature/band), platelet, basophil, eosinophil, RBC, monocyte, lymphocyte
what is the main fxn of an RBC?
carry 02
what is the main fxn of platelets?
clot formation, a main component of hemostasis.
what is the main fxn of lymphocytes?
(B and T cells) respond to viral and other infections
what are the main fxns of monocytes, neutrophils, eosinophils, and basophils?
respond to bacterial, fungal and parasitic infections
lymphocytes: general appearance?
round nuclei, minimal cytoplasm, no granules
monocytes: general appearance?
indented nucleus, more cytoplasm than lymphs
basophils: general appearance?
intense blue granules
eosinophils: general appearance?
intense red granules which are stained by eosin dye
mature neutrophils: general appearance?
3 lobes, pale granules
immature neutrophils: general appearance?
“bands” - nucleus has not yet separated into 3 lobes
in the CBC, what does WBC mean?
total number of all white blood cells per mm3 (microliter)
in the CBC, what does the platelet count mean?
total number of platelets per mm3 (microliter)
in the CBC, what does the hematocrit mean?
volume red cells/volume plasma
in the CBC, what does the hemoglobin mean?
spectrophotometric meas of hemoglobin absorbance
all the blood cells arise from what?
common hematopoietic stem cell
a stem cell can generate what two general types of cells?
lymphoid stem cells and myeloid precursors
what cells come from the lymphoid stem cell?
NK lymphocytes, T lymphs, B lymphs
what cells come from the myeloid precursor?
platelets, monocytes, neutrophils, RBCs
what is the shorthand for writing blood count values on a chart?
WBCs are on the left, platelets on the right. Hematocrit on bottom, hemoglobin on top
what cell surface protein identifies HSCs?
CD 34 (glycoprotein)
most of the time, HSCs are in what part of the cell cycle?
G0.
how might it benefit HSCs to spend time in G0 (in quiescent state)?
resistant to toxic insults such as radiation or chemicals - because are able to repair DNA before entering the cell cycle at some later time point.
can HSCs generate non-hematopoietic cells?
yes, according to recent mouse experimental data. however, this theory of HSC ‘plasticity’ remains controversial.
what are the sites of hematopoiesis in the developing fetus?
first few weeks: yolk sac
6 wks til 6-7 months: liver/spleen
liver/spleen continue thru postpartum week 2
at 6-7 months, the bone marrow picks up, eventually becoming the only source.
in the adult, where is hematopoiesis taking place?
axial skeleton, proximal ends of femurs and humeri.
in times of need, what organs may be recruited for hematopoiesis?
liver/spleen. also, the bone marrow that has been replaced by fat may revert to hematopoiesis.
production of each type of blood cell controlled by what?
cytokines or interleukins
growth factors responsible for hematopoietic development?
glycoprotein hormones
what is the source of these glycoprotein hormones?
local cells in marrow (T-cells, macrophages, endothelial cells, fibroblasts) or come from circulation (ie erythropoietin from kidney)
biological effects of the growth factors and glycoprotein hormones mediated by what?
specific cell surface receptors
what is the stimulus to produce more RBCs?
02 levels in kidney, which lead to erythropoietin production
what is the stimulus to produce more WBCs?
inflammation, invasion of microbes
biological effect of erythropoietin?
erythrocyte production
what does interleukin 3 do?
stimulates proliferation and differentiation of granulocyte, macrophage, eosinophil, mast cell, magakaryocyte, Tcell, Bcell, and early myeloid stem cells.
what is G-CSF?
granulocyte colony stimulating factor
what does G-CSF do?
stimulates granulocyte lineage proliferation and differentiation. stimulates early myeloid stem cells. increases neutrophil phagocytosis. releases neutrophils from bone marrow.
what is GM-CSF?
granulocyte-macrophage colony stimulating factor
what does GM-CSF do?
stimulates granulocyte, macrophage, and megakaryocyte proliferation and differentioation, stims myeloid stem cells. in presence of erythropoietin, stimulates erythropoeises. enhances phagocytic activity of neutrophils.
what does interleukin-1 do?
activates resting T cells, co-factor for T cell and B cell proliferation. stimulates early myeloid stem cells. induces production of G-CSF, GM-CSF, Il-6, CSF-1, IL-3, IL-2 (growth factors)
what does interleukin-2 do?
growth factor for T cells
when evaluating a patient with anemia, what is one of the first points of differentiation?
the cause of the anemia: whether from disrupted erythropoiesis or some other effect (hemorrhage)
increased production of RBCs leads to increased what in the blood?
reticulocytes, which have mRNA in them. can be detected via staining.
if the number of reticulocytes is increased in response to anemia, what is the conclusion?
source of anemia is not RBC production problems.
in normal patients, how do the erythropoietin levels normally increase in response to anemia?
exponentially
what is pancytopenia?
decreased WBC, neutrophils, hemoglobin, platelets
what is the first line treatment for aplastic anemia?
immunosuppression, to lessen the autoimmune reaction
how will a bone marrow biopsy look in a pt with pancytopenia?
acellular
while waiting for transplant, what might be administered to support blood counts?
G-CSF, erythropoietin, and platelet transfusions
what is the etiology of aplastic anemia?
autoimmune destruction of the HSCs
if a pt does not respond to immunosuppression, what is the next option?
allogenic HSC transplantation.
is there a cytokine for platelets that is clinically available?
no, have to do transfusions
