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MICROBIOLOGY: CMOD-Week 1 > Strom - Blood Cells > Flashcards

Strom - Blood Cells Flashcards

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1
Q

What agents are added to prevent blood from clotting in a sample?
- how do these work?

A

Chelating agents like EDTA or Citrate

Both chelate Ca2+ which causes the blood to clot

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2
Q

What is used to stain blood cells?

  • chemical properties?
  • solubility?
  • what in the cell does it stain?
A
  • Eosin (wright-giemsa stain)
  • Eosin = Aromatic and Acidic (neg. charge)
  • soluble in EtOH, NOT water
  • Stains HYDROPHOBIC BASIC (positivity) macromolecules (e.g. hemoglobin and some others)
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3
Q

What gives hemoglobin its positive charge?

A

Fe++ at the center of the heme group

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4
Q

What are the 3 key morphological features of normal red cells?

A
  1. Bi-concave Disks
  2. Uniform in size
  3. Central pallor occupies 1/3 of disk diameter
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5
Q

What morphological change happens to RBCs when patients are iron deficient?

A

Enlarged Central Pallor

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6
Q

What are two possible causes of eosinophilia?

A
  1. Allergies

2. Infections with parasites

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7
Q

Eosinophils

  • presence in blood
  • biological role
  • what is contained in the granules?
A

Rare in blood (less than 5% of leukocytes)

Biological role:
- protect against parasites

Major Basic Protein (MBP) found in granules

**Increase during allergic Reaction

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8
Q

Methylene Blue

  • Chemical Characteristics
  • Solubility
  • What does it stain?
A
  • Methylene blue is Aromatic and Basic
  • Soluble in Water or MeOH

Stains:

  • Nucleic Acids
  • Some proteins
  • Basophils
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9
Q

Basophils

  • Presence in Blood
  • Biological Role
  • How it works
  • when are they elevated
A

Presence in Blood:
- Rare (1% leukocytes)

Biological Role:
- Parasite protection

How it works:
- Secretes Histamine in response to IgE-bound antigens

When are they Elevated:
- Presence in Blood increases during an allergic reaction

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10
Q

What is pale blue cytoplasm referred to?

A

Amphiphilic

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11
Q

Monocytes

  • what do they do?
  • Where do they do it?
  • Distinguishing features
A

Job:
- Gather information and share it with lymphocytes

Where:
- Information is shared in Lymphatic Tissue

Distinguishing Features:

  • Amoeboid nucleus
  • lack of granules
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12
Q

When does monocytosis occur?

- is monocytosis usefule for a differential diagnosis?

A
  • Low grade or cryptic infections
  • autoimmune conditions

NOT useful for differential Dx

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13
Q

Monocytes

  • Percentage of Leukocytes
  • Give rise to…
  • Biological Role
  • How it works
A

3-8% of Leukocytes

Give Rise to Macrophages

Biological Role:
Macrophages bind antigens and initiate immune response

How it works:
Phagocytose invading organisms and present their antigens to helper T-cells (CD4+) via MHC-II

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14
Q

Lymphocytes

  • Percentage of blood leukocytes
  • Type of most peripheral blood lymphocytes
  • when do you see an increase?
A

Percentage:
20-30% of blood leukocytes

  • T-cells are the most common type of peripheral blood lymphocytes

Increase:

  • Leukemia
  • Viral Syndromes
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15
Q

What cell types are difficult to distinguish morphologically and are therefore referred to as mononuclear cells?

  • why report mononuclear cell number?
  • how could you attempt to differentiate these cell types?
A
  • Reactive lymphocytes are often hard to tell from monocytes
  • Elevated mononuclear cells helps you know granulocytes are NOT elevated
  • Lymphocyte nucleus is usually round while monocyte nucleus is usually more S-shaped (amoebiod)
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16
Q

What is the 1st thing you should determine when beginning your differential diagnosis on any Blood Cell or Platelet?

A

Determine if its Reactive or Neoplastic

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17
Q

Compare the lifespan of lymphocytes to neutrophils.

A

Lymphocytes are long lived while neutrophils die in a day or so

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18
Q

Neutrophils

  • staining characteristics
  • % of leukocytes
  • biological role
  • how they work
A

Staining:
- Light staining with eosin and methylene blue

40-70% of all leukocytes

Biological Role:
- Ingest and kill invading organisms

How they work:

  1. Chemotaxis
  2. Phagocytosis
  3. Degranulation
  4. Formation of Extracellular traps (NETS)
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19
Q

How do dead neutrophils still help to kill bacteria?

A
  • Forms NETS (neutrophil extracellular traps) from their chromatin
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20
Q

What are the benefits and downfalls of NETS formation by neutrophils?

A

Benefits:
- Captures Bacteria

Downfalls:
- May contribute to sepsis

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21
Q

What is Pre-eclampsia?

- associated cells type?

A
  • Sepsis Associated condition in which severe threatening hypertension occurs during pregancy.
  • Can be caused by NETS secreted by neutrophils
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22
Q

T or F: KNOWING THE NEUTROPHIL COUNT IS ESSENTIAL IN EVALUATING ANY INFECTIOUS DISEASE

A

TRUE

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23
Q

Why do oncologists follow neutrophil count so closely?

A
  • It is the first thing to drop as a side effect of chemotherapy
  • This is a result of the fast turnover (1 day) of neutrophils
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24
Q

where are neutrophils made?

A

Bone Marrow, neutrophil production accounts for over 2/3 of bone marrow space

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25
Q

What 3 things does chemotaxis refer to?

A
  1. Communication
  2. Navigation
  3. Propulsion

**Signal is received from environment and cells respond by moving to affected site

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26
Q

What causes Leukocyte Adhesion Defect?

A
  • Congenital defects in a component of (lymphocyte function associated antigen 1) LFA-1 (CD18)
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27
Q

What is a CD number?

A

“Cluster of Differentiation”

  • When 2 or more monoclonal antibodies complete for the same binding protein they are given a CD number
    e. g. CD18
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28
Q

What are the 3 target recognition methods for neutrophils?

- are these associated with innate or acquired immunity?

A
  1. Toll-Like Receptors
    - innate immune system components
    - Old
  2. Complement Fixation
    - innate or adaptive immunity
    - Newer
  3. Fc Receptors that recognize antibodies bound to targets
    - Newest
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29
Q

What weaponry to neutrophils posses?
- be specific (4 things)

**NEED TO KNOW

***COME BACK TO THIS AND FIX IT

A

They degraulate and release their contents

  1. Myeloperoxidase (MPO) - enzyme that makes hypochlorite (bleach)
  2. Lysozymes - break down bacterial cell wall (NAM-NAG bond break)
  3. Defensins
  4. NETS
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30
Q

Chronic Granulmatous Disease

  • What causes it?
  • Characteristic features?
A

Defect in Hypochlorite-generating system of neutrophils

Characteristic Features:
- Granulomas - clusters of ineffectual dying neutrophils

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31
Q

What is immunostaining?

A
  • Use an antibody to find a protein of interest in the cell and attach an enzyme to the antibody that converts the soluble precursor into an insoluble pigment
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32
Q

What kind of antibody would you use to do an immunostain for neutrophils?

A

MPO (Myeloperoxidase) antibody

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33
Q

What is a left shift of granulocytes and why does it happen?

A

Left Shift:
- BACTERIAL infection causes ramped up production of nuetrophils and immature band cells get dumped into blood earlier than normal

34
Q

What are two possible causes of a left shift?

A
  1. Bacterial infection (19/20)

2. Neoplastic (1/20)

35
Q

Two granule types seen in neutrophils.

  • when are they seen?
  • where are they seen?
A

Primary Granules

  • Dark Blue
  • Usually only seen in early myeloid precursors of bone marrow but seen in blood during infection

Secondary Granules:
- Salmon-pink

36
Q

What is toxic granulation?

A
  • Presence of Primary Granules in blood
37
Q

Platelets

  • Concentration
  • lifespan
  • biological roles (4)
A

Concentration:
- High (100x that of white cells)

Lifespan:
- 9-10 days

Biological Roles:

  1. Primary Hemostatic Plug
  2. Stimulate coagulation cascade (fibrin)
  3. Stimulate would healing (fibroblasts)
  4. Immune Function (pathogen inactivation)
38
Q

How does platelet adherence work?

A
  • Damage to BV causes exposure of subendothelial Collagen
  • Platelets adhere either directly or via vWF (von Willebrand factor - a circulating adaptor protein)
  • Adherence induces “platelet activation’
39
Q

vWF

  • where is it located?
  • structure?
  • interacts with?
  • what receptor binds it?
A

Location:
- Blood Plasma

Structure:
- Coiled Cable, multimer made of identical monomers

Interactions:
- Uncoils to bind Collagen and Platelets

Receptor:
GP1b receptor of platelets bind it

40
Q

What diseases result from a lack of GP1b or vWF?

- symptoms

A

Deficient GP1b:
Bernard-Soullier syndrome

Deficient vWF:
Von Willebrand’s disease

Both result in mild bleeding tendencies in mucocutaneous locations

41
Q

What would you expect to see in a patient with excess vWF?

A
  • Thromboses
42
Q

How does increased affinity from activated platelets come about?
- what is there increased affinity for?

A

Increased binding affinity for:

  1. Collagen
  2. vWF
  3. Fibrinogen
  • Caused by:
  • GPIIb/IIIa conformational change (platelet surface protein complex) - we have DRUGS that can block this
43
Q

What are the two components to platelet activation?

A
  1. Increased affinity for collagen, vWF, and Fibrinogen

2. Autocatalytic activation via secretion of a number of mediators which results in activation

44
Q

What happens in autocatalytic activation?

A
  1. ADP is released, it rebinds to ADP-receptor then causes more ADP and MEDIATORS to be released.
  2. Thromboxane A2 (TXA2) gets released then comes back to bind on TXA2-receptor, causes TXA2 production to increase and Granule secretion
45
Q

What drug inhibits ADP receptor binding and TXA2 receptor binding in autocatalytic activation?

A

ADP receptor blocked by Clopidogrel

TXA2 receptor blocked by asprin

46
Q

What 3 things are stored in alpha granules?

A
  1. vWF
  2. Factor V
  3. Fibrinogen
47
Q

What are the 2 parts to platelet aggregation?

A
  1. Augmentation of the coagulation cascade

2. Crosslinking of platelets into the “platelet plug”

48
Q

How do platelets augment the coagulation cascade?

A

Release of alpha-granuals containing vWF, Fibrinogen, Factor V

49
Q

Platelet Crosslinking

- how does it occur?

A
  1. Platelet bound by Fibrinogen

2. Fibrigogen used to make fibrin

50
Q

How do platelets aid in wound healing?

A

Secretion of Fibroblast Growth and Chemotactic Factors (e.g. Platelet Derived Growth Factor PDGF)

51
Q

Why do patients with severe bacterial infections involving the bloodstream (bacteremia) and associated organ disfunction (sepsis) often show Thrombocytopenia (low platelet count)?

A
  1. TLR’s on the platelet surface cause them to bind bacteria

2. Antibodies bound to the bacteria cause uptake by macrophages

52
Q

When might you see a giant platelet in the peripheral blood?

A
  1. Platelet Production is Ramped up

2. Diseases affecting the bone marrow

53
Q

What are the immunological functions of platelets?

A
  1. Store and secrete defensins
  2. They recognize and bind bacteria via TLRs
  3. Activated cells stimulate expression of ICAM-1 on endothelial cells
  4. Bind malaria-infected red cells and kill parasite by secreting a factor
54
Q

RBC

  • % of cells in blood
  • Lifespan
  • % wt. hbg in RBCs
A
  • 99% of Cells in blood
  • 120 day lifespan
  • RBCs - 90% Hb by wt.
55
Q

What allows hemoglobin to bind and dump so much O2 compared to myoglobin?

A

Hb
- Sigmoidal curve produced by cooperative binding allows for sharp release of O2 at higher pO2 (like that in muscle)

Mb
- Not sigmoidal so only way to increase release is to reduce affinity which reduces maximal binding (100% saturation)

56
Q

Bohr Effect

- cause

A

Low pH:

  • Hb has lower Affinity for O2 at Low pH
  • This causes more O2 to be dumped in O2 deficient tissues where lactate is high driving pH down.

High pH:

  • CO2 blown off in lungs Raises pH
  • Hb binds more tightly at high pH
57
Q

What tissue type would you expect to have the highest levels of 2,3 DPG and why?

A

2,3 DPG would be highest in HYPOXIC tissues

why?

  • Lactate builds up and glycolysis intermediates back up
  • 1,3 DPG is shunted to 2,3 DPG via the action of DPG mutase
58
Q

How do RBCs offset osmotic pressure due to high Hb levels?

A

Pumps that use ATP (Na+/K+ pump)

**If these pumps fails H2O will rush in and the cell will burst

59
Q

What is the significance of the biconcave disk of RBCs?

- How is this shape maintained?

A

Allows for 360º Folding

Spectrin
- Dimeric Polymer is linked to…
Ankyrin
- transmembrane protein

60
Q

What shape are RBCs that lack Spectrin or Ankryin?

A

Elliptical or Spherical

61
Q

What is the most important group of microorganisms that thrive on Hb?

A

Plasmosdum

  • 4 species in this family cause malaria
62
Q

T or F: Hb concentration in RBCs is so high that even small changes from oxidative stress etc. can cause Hb precipitation

A

True

63
Q

What are the plasma and intracellular concentrations of Na+ and K+?
- why are ion concentrations so important to RBCs?

A

Plasma:
[Na+] 140 mM
[K+] 4 mM

-144 mM outside

RBC:
[Na+] 11 mM
[K+] 100 mM

  • 111 mM inside

**Lower Ion Concentrations in the cell prevent H2O from trying to rush in

64
Q

Why is an antioxidant system important to RBCs?

A
  1. O2 is a powerful oxidant
  2. -SH groups on cysteine oxidize to form -S-S- crosslinks
  3. Oxidized Fe+++ cannot carry O2
65
Q

What results from Oxidized Fe+++?

- why?

A
  • Hypoxia, because Fe+++ cannot bind O2

* patient can be hypoxic in spite of not being anemic or having lung disease

66
Q

Why do defects in glycolytic enzymes result in hemolytic anemia in children?

A
  • RBCs only use glycolysis for ATP and ATP is needed to run the Na+/K+ pump to keep H2O from bursting the cell
67
Q

What is the role of G6P dehydrogenase in RBCs?

A
  • Involved in the Pentose Phosphate Pathway that makes NADPH

- NADPH is needed to reduce Glutathione so that cell can perform antioxidant function

68
Q

What is the complement system?

A
  • A group of proteins in the bloodstream that lyse invading organisms or host cells containing them.
69
Q

Define hypochromia

A

lack of color

70
Q

Define anisocytosis

A

abnormal distribution of RBC sizes

71
Q

Define Poikilocytosis

A

Abnormal RBC shape

72
Q

What does it mean if RBCs pick of methylene blue dye?

  • what is the called
  • when does it happen?
A

RBCs have lots of Nucleic Acids (RNA)

POLYCHROMIA = Called Reticulocytes

These are seen when patients are loosing RBCs somehow

73
Q

What does the presence of bite cells indicate?

- how do they arise?

A
  • G6PD deficiency

- Come about because phagocytes bite out the oxidize Hb from the cell

74
Q

What are Heinz bodies?

A
  • Oxidized Hb forms Clumps
75
Q

What are scistocytes?

A

RBCs that look like they’ve been cut in half

  • Happens via mechanical lysis (aka Microangiopathic Processes)
76
Q

What are 3 forms of neutrophil that may be expelled during a bacterial infection?

A
  1. Band Forms
    - Horseshoe Shaped Nucleus
  2. Metamyelocytes
    - Bean shaped nucleus
  3. Myelocytes
    - Round Nucleus

**Remember neutrophiles should have a lobular nucleus

77
Q

What if you have an anemic patient but you don’t see a single reticulocyte in a blood smear?

A
  • they may have a bone marrow defect because immature RBCs (reticulocytes) should be kicked out in response to blood loss
78
Q

What would happen if oxidatitive phosphorylation occurred in RBCs?

A

They would consume their own product

79
Q

What is DAF (CD55)?

- where is it found?

A

DAF - decay accelerating factor

  • presented on RBCs to prevent complement from acting on RBCs, this prolongs the life of the cell
80
Q

What happens if you have a mutation in your cytochrome b5 reductase gene?

A

Methomeglobin - from Fe+++ not being able to be reduced

NOTE: this requires NADPH

MICROBIOLOGY: CMOD-Week 1 (10 decks)

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