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CMOD Week 7 > Hematopoiesis > Flashcards

Hematopoiesis Flashcards

1
Q

What is the normal range for WBC?

A

4.8-10.8 K/ul

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2
Q

What is the normal range for RBC? Male and female?

A

4.7-6.1 (male), 4.2-5.4 (female). All x10^6/ul

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3
Q

What is the normal range for Hgb? Male and female?

A

14-18 (male), 12-16 (female) g/dL

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4
Q

What is the normal range for Hct (hematocrit)? Male and female?

A

42-52% (male), 37-47% (female)

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5
Q

What is the normal range for MCV (average volume of RBC)?

A

80-100 fL

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6
Q

What is the normal range for RDW (Red Blood Cell Distribution Width. It is a measurement of the size of red blood cells)?

A

11.5-14.5%

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7
Q

What is the normal range for MCH (the average amount of hemoglobin in the average red cell)?

A

27-31 pg

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8
Q

What is the normal range for MCHC (mean cell hemoglobin concentration, which is the average concentration of hemoglobin in a given volume of blood. The MCHC is a calculated value derived from the measurement of hemoglobin and the hematocrit)?

A

32-36 %

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9
Q

What is the normal range for Plts?

A

150-400 K/ul

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10
Q

What is the normal range for MPV (mean platelet volume)?

A

7.4-10.4 fL

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11
Q

What is the normal percentage range for neutrophils in WBCS?

A

36-75%

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12
Q

What is the normal percentage range for lymphocytes in WBCS?

A

20-50%

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13
Q

What is the normal percentage range for monocytes in WBCS?

A

3-10%

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14
Q

What is the normal percentage range for eosinophils in WBCS?

A

0-4%

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15
Q

What is the normal percentage range for basophils in WBCS?

A

0-2%

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16
Q

How is hemoglobin measured?

A

by spectrophotometry.

Lyse the red cells, add cyanide to generate blue color, quantify it by % absorption

NOTE: Any turbidity in a blood specimen (such as excess lipoproteins after a fatty meal) will ALSO absorb non-blue light and result in artifactually high HgB measurement

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17
Q

How can red cells be measured by manual methods?

A

centrifugation- put anti coagulated blood in tube and spin down the cells. Can use a capillary tube (aka a spin hematocrit)

A/B= hematocrit, where A is the red part and B is the supernatant

NOTE: EDTA-containg tubes (lavender top) and citrate containing tubes (blue top), and heparin-containing tubes (green top)

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18
Q

How else can red cell be measured?

A

faster and more precisely via conductivity via the ‘coulter chamber” using DIRECT CURRENT

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19
Q

How does a coulter chamber work?

A

consists of a small container of fluid placed in a large container of the same fluid. The small container has a tiny aperture in it. Fluid is pumped at a precise rate into the large container, through the aperture, into the smaller container, and finally into a waster container. Since red cells outnumber other cells by a factor of about 1000, just counting all the cells will essentially give you the red cell count.

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20
Q

How is manual leukocyte differential measured?

A

done by visual inspection of 100 leukocytes, but only done on request because very laboring intensive

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21
Q

How can leukocytes be measured automated?

A

If you lyse the red cells in a blood specimen and then run the leukocytes through a coulter chamber, you can count the white cells and measure their volume similar to red cell measurements.

But if you change the setup by simultaneously measuring the resistance to radio frequency alternating current, you can measure what’s inside the cells (lobulate nuclei, for example vs spherical ones) instead of their size.

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22
Q

What is a drawback of the automated leukocyte measuring technique?

A

eosinophils and basophils are not well seperated from other populations

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23
Q

How can you separate eosinophils and basophils out then?

A

flow cytometer. Prior to the coulter chamber, the cells are hydrodynamically focused and run through a chamber in which they are hit by a laser. The amount of deflected light is the called the side scatter measurement and it provides a measure of the cytoplasmic granularity of the cells. This allows separation of basophils and eosinophils from neutrophils

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24
Q

Hematocrit is usually three times the value of hemoglobin. What might cause a smaller ratio?

A

fatty foods. Any turbidity in a blood specimen (such as excess lipoproteins after a fatty meal) will ALSO absorb non-blue light and result in artifactually high HgB measurement

So here, hemoglobin increases and hematocrit remains the same

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25
How would small red blood cells affect hemoglobin and hematocrit?
they would both decrease
26
What might cause hematocrit to decrease?
red cells in a coulter counter may not be going through in a single file line and so the counter may count two RBCs clumped together as one, resulting in an artifically lowered red cell count, and thus, a lower hematocrit level hemoglobin will not be affected
27
What is a reticulocyte?
immature red cell that is slightly bigger than mature ones and have a bluish tint caused by residual RNA
28
An increase in reticulocytes would result in what comment in a CBC?
polychromasia comment should be made
29
Can a hematology anayzer count reticulocytes?
Yes, very accuratley- **can be used to assess whether an anemia is due to impaired red cell production**
30
What is IPF?
immature platelet fraction-marketed by Sysmex as the platelet equivalent of reticulocyte count
31
What does a high IPF mean?
a thrombocytopenia is occurring due to rapid platelet consumption
32
What is a major problem with IPF?
it can always increase due to thrombocytopenias due to reduced platelet production- as well as the intended rapid platelet consumption
33
Current hematology analyzers have what capabilities?
automated spectrophotmetry, conductivity, and flow cytometry all in one
34
What things wont hematology analyzer count?
1) Bands- and other immature granulocytes (counted as neutrophils) 2) Blasts- may be counted as lymphocytes or monocytes 3) Red cell fragments- may not be detected, or counted as platelets 4) Platelet clumps- not always detected and may result in an artifactual thrombocytopenia
35
What are blasts?
early blood cell precursors which biologically similar to the earliest forms seen in bone marrow. These are small round cells with hypodense chromatin and none of the morphologic features associated with differentiation
36
The presence of blasts correlates to what diseases?
acute leukemias
37
How do platelet clumps occur as a lab artifact?
occasional patients have antibodies to platelet antigens which are not exposed in vivo. They cause no problems at all. But in the presence of EDTA, these antigens may be exposed, causing platelets to clump. The hematology analyzer will call this thrombocytopenia (which must be caught). This is called pseudothrombocytopenia. If it is caught, citrate tubes can be used instead.
38
After getting an automated leukocyte count in suspected pneumonia, what would you do?
order a manual count
39
What are pluripotent stem cells?
1) Rare (1 in 20 million) 2) Cant be ID'd be morphology 3) Expresses receptors for growth factors 4) subset of blasts in bone marrow
40
What cells derive directly from pluripotent stem cells?
Common myeloid progenitor cells and common lymphoid progenitor cells
41
What cells derive directly from common myeloid cells?
burst forming units (BFUs) and colony forming units (GMEo and baso)
42
Can you use a microscope to pick out BFUs from the bone marrow?
No. Cant distinguish from CFUs this way- most likely they don't have any features associated with differentiation at all- aka they are "blasts"
43
How are BFUs defined?
by the fact that if you dump a mixture of cells from bone marrow into a peri dish, certain growth factors cause their formation
44
What is TPO?
thrombopoietin
45
What is EPO?
erythropoietin
46
What is the order of cell growth from blast to bands/neutrophils (aka granulopoiesis)? What is the relative distribution of each in bone marrow?
``` blasts (4%), promyelocyte (2-8%), myelocyte (10-13%), metamyelocyte (10-15%), bands and neutrophils (25-40%) ``` increase because cell division is associated with the growth process last cell division is at myelocyte stage
47
What is the major regulator of granulopoiesis?
GM-CSF
48
Eythroblast production is stimulated by what?
hypoxia, as sensed by renal peritubular cells. *****Thus, renal failure- productive anemia ******
49
How are erythroblasts made in bone marrow?
``` blasts, pronormoblast basophilic erythroblast, polychromatophilic erythroblast, normochromic erythroblast ``` there are typically 4-5 divisions per stage
50
How are platelets made?
done via megakaryocytes (multiple divided nuclei- up to 16-32 haploid genomes) They extend snakelike tubes called proplatelets into the fenestrated blood vessels int he bone marrow (aka sinuses), and mature platelets get cleaved one at a time from the ends of the proplatelets
51
Where is TPO made?
liver in response to low platelet levels
52
What does TPO do?
bind to platelets and megakaryocytes stimulating their production from immature precursors and platelet production from mature megakaryocytes
53
How is heme made?
drop a porphyrin ring with a Fe2+ inserted in it into globin
54
Where are porphyrin rings made?
mitochondria
55
How is porphyrin made?
succinyl CoA and glycine needed
56
How is glycine provided?
Via diet and a system that makes glycine in the liver using B12 and folate (heme is needed for CYP450 in the liver as well)
57
What enzymes are used in porphyrin synthesis?
ALA synthetase and ferrochelatase
58
What happens if these enzymes are defective?
a disease family called porphyrias develop (inherited)- patients must stay away from light and sun
59
What are sideroblasts?
When ferrochelatase is defective, iron transport into mitochondria continues even without a porphyrin ring to put it in, leading to abnormal, overloaded red precursors called sideroblasts
60
Dietary iron mostly exists in the oxidized state, but it most be reduced for hemoglobin use. How is this done?
reduced in the duodenum via duodenal reductase (cytochrome b) using vitamin C (aka ascorbate) and then taken up in small intestine Thus, you can treat iron deficiency with vitamin C
61
What happens once iron is taken up?
it is re-oxidized for transport and then taken up by cells via a transferrin receptor
62
How does iron travel through blood? Freely?
No, via tranferrin, which only binds Fe3+, not Fe2+. NOTE: free iron in blood= more bacterial growth and more superoxide radicals= BAD
63
Where in the body are there massive reservoirs of iron?
macrophages in bone marrow, liver, and spleen
64
Is the iron reservoir in macrophages in those tissue free?
No, bound to ferritin. NOTE: Transferrin is also used to transfer this iron is dietary levels drop
65
What transporters are used to shuttle iron through gut enterocytes?
DMT-1 (apical) and ferroportin (basement membrane)
66
What are DMT-1 levels regulated by?
iron levels- more iron- more transcription
67
What are ferroportin levels regulated by?
hepcidin (made in liver) less iron= upregulation on enterocytes AND in iron reservoir tissues for mobilization
68
Describe ferroportin regulation.
Increasing levels of transferrin bound iron increase hepcidin production, which INHIBITS ferroportin expression in macrophages and enterocytes and vice-versa. Thus, high hepcidin= anemia.
69
What is hemochromatosis?
When iron/transferrin levels are low, hepcidin is down-regulated, causing ferroportin to increase iron levels that are wrongly deposited to inappropriate tissues, causing damage.
70
Hereditary hemochromatosis is caused by what?
Most caused by mutations of HFE
71
What does globin synthesis require?
alpha and beta globin genes, and amino acids
72
Important paradox: Although red cells are anuclear, they requires LOTS of DNA in order to replicate frequently during development
Important paradox: Although red cells are anuclear, they requires LOTS of DNA in order to replicate frequently during development
73
Red cell replication requires what?
deoxynucelotide triphosphates, which need ribonucleotide reductase, thymidine (which requires folate and B12)
74
How does folate circulate through the body? Significance?
as THF. THF can be methylated to form up to 4 different compounds used in different biosynthetic processes (i.e. the N-10-formyl form in purine synthesis and the N5, N10 methylene form in thymidine synthesis). Thus, folate or B12 deficiency= anemia
75
What else is needed for purine synthesis?
PRPP and gln, glu and asp (to accept methyl from N-10-formyl) and NAPDH (for methylation of THF to N-10-formyl THF)
76
What else is needed for pyridime synthesis?
N5, N10- methylene THF transfers methyl to dUMP to form dTMP (using thmidylate synthase) resulting in dihydrofolate, which is recycled to THF via dihydrofolate reductase using NADPH, which is then cycled again to N5, N10 methylene THF as serine become glycine via serine hydroxymethyl transferase
77
Why would B12 deficiency lead to anemia?
lack of B12 traps folate in the N5-methyl form (that is needed to convert homocysteine to methionine), making it unavailable for nucleotide synthesis
78
Lack of B12 would also cause?
demyelination of some areas of the spinal cord, because it needed for production of sphingomyelin, a component of myelin
79
Red cell production is regulated primarily via what?
erythrypoietin (Epo).
80
What does Epo require to function?
normal kidneys, a normal bone-marrow microenvironment (i.e. no myelofibrosis), functional EPO-R receptor
81
Describe the structure of Epo (on erythroid precursors) and Tpo (on mature or immature megakaryocytes).
They are both transmembrane dimers with two copies of a relatively inactive tyrosine kinase (Jak-2), which can then phosphorylate STATs, which dimerize and go to nucleus
82
What is the receptor of Tpo called?
Mpl
83
How can iron be measured in a lab?
two classes: 1) measurement of iron transport systems and 2) measurement of storage pool iron
84
What are some ways to measure iron transport systems?
1) serum iron- measure of transferrin-bound iron 2) total iron binding capacity- total amount of transferrin in circulation 3) transferrin saturation (serum iron divided by transferrin levels)
85
What are some ways to measure storage pool iron?
1) serum ferritin- trace amount of ferritin leak from reservoir in relation to total amount of pooled iron (don't know why)
86
T or F. Serum ferritin is the MOST useful initial measurement you can get of iron metabolism in patients with unexplained anemias.
TRUE.
87
T or F. Bone marrow cellularity decreases with age.
T. Cells are replaced with fat.
88
To a first approximation, the fraction of normal bone marrow cells taken up by hematopoietic cells is:
100-age

CMOD Week 7 (16 decks)

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