Cells and Organs of the Immune System Flashcards
1
Q
Hematopoiesis is?
A
Formation and development of erythrocytes and leukocytes (RBC and WBC)
2
Q
4 kinds of WBC
A
- Granulocytes
- Mast cells
- Monocytes
- Lymphocytes (B, T, NK, and NKT cells)
3
Q
Granulocytes - 3 kinds
A
Neutrophils, basophils, eosinophils
4
Q
Lymphocytes - 4 kinds
A
T cells, B cells, NK cells, NKT cells
5
Q
What cells are generated from hematopoietic stem cells?
A
RBC, all WBC, and platelets
6
Q
2 important characteristics of hematopoietic stem cells
A
- Self renewal
2. Multi lineage differentiation potential (aka. pluripotent)
7
Q
First differentiation of hematopoietic stem cells gives?
A
Myeloid progenitor and Lymphoid progenitor
8
Q
Lymphoid Progenitor cells give rise to?
A
NK cells, Dendritic cells, and T/B progenitor cells
9
Q
Myeloid Progenitor cells give rise to?
A
Dendritic cells, mast cells, megakaryocytes (make platelets), progenitors of: basophils, eosinophils, granulocyte/monocyte.
10
Q
granulocyte/monocyte progenitors give rise to
A
Monocyte –> either macrophage or dendritic cell
Neutrophil
11
Q
Basophils can further differentiate into?
A
Mast cells
12
Q
T cell progenitor can further differentiate into?
A
TH helper cell
TC cytotoxic cell
13
Q
Hematopoietic stem cells are found in the?
A
Mainly bone marrow but some can be found in the blood
14
Q
sites of hematopoiesis: 0-2 months (fetus)
A
yolk sac
15
Q
sites of hematopoiesis: 2-7 months (fetus)
A
Liver and spleen
16
Q
sites of hematopoiesis: 5-9 months (fetus)
A
Bone marrow
17
Q
sites of hematopoiesis: infants
A
Bone marrow of almost all bones
18
Q
sites of hematopoiesis: adults
A
BM of vertebrae, ribs, sternum , skull, sacrum, pelvis and end of femurs
19
Q
Bone marrow is an example of ___ lymphoid tissue
A
Primary
20
Q
3 Basic components of bone marrow are:
A
- stem cells
- microenvironment (stromal cells and extracellular matrix)
- Hematopoietic growth factors
21
Q
Extracellular matrix : role in bone marrow
A
Attachment site of stem cells and progenitor cells
22
Q
Stromal cells: 4 roles in bone marrow
A
- Physical support for stem cell growth
- Provide nutrients 3.produce GF f
- express adhesion molecules to induce differentiation
23
Q
Stromal cells include which kinds of cells?
A
Macrophages, fibroblasts, endothelial cells, and adipocytes
24
Q
Hematopoietic growth factors are:
A
- glycoproteins in low concentrations
- produced by many cells (stromal, monocytes, lymphocytes)
- can affect more than one cell lineage
25
Hematopoietic growth factors show ____ action with other growth factors
additive or synergistic
26
3 key regulatory factors for neutrophil granulopoiesis:
IL-3, GM-CSF, G-CSF
27
2 characterizations of maturation of neutrophil granulopoiesis
1. Nuclear segmentation
2. Acquisition of primary, followed by secondary granules
* takes about a week to fully mature
28
Granulopoeisis is controlled by:
Negative feedback by mature forms
29
Monocytopoiesis key hematopoietic growth factor?
M-CSF
30
Maturation characteristics of monocytopoiesis
1. Gradual nuclear folding
| 2. Acquisition of cytoplasmic granules
31
Monocytopoiesis: Stages in development
1. Monoblast
2. Promonocyte
3. Mature monocyte
32
Monocytopoiesis has the same progenitor cell as for?
segmented neutrophils
33
Lymphopoeisis generates?
T, B, NKT, and NK cells
34
Lymphopoeisis: key hematopoietic growth factors
IL-2, IL-3, IL-4, IL-7
35
Lymphopoeisis maturation stages are defined by?
Surface antigen presentation rather than morphological features (CD antigens)
36
B cells mature from their progenitors in the ?
Bone marrow
37
NK cells mature from their progenitors in the ?
Bone marrow
38
T cells mature from their progenitors in the ?
1. Bone marrow (prothymocytes)
| 2. Thymus (thymocytes)
39
Positive selection
Testing the T cells to make sure they are reactive to foreign antigen
40
Negative selection
Testing to make sure the T cells are not self reactive `
41
Production of mature blood cells increases ___ fold in response to inflammation or infection
10-20
42
4 ways in which homeostasis of hematopoiesis is maintained
1. Controlling the level/types of cytokines produced by stromal cells
2. Production of cytokines by other cell types like activated T cells and macrophages
3. Regulation in the expression of receptors for hematopoietically active cytokines in stem cells and progenitor cells
4. Removal of some cells by apoptosis
43
Difference between apoptosis and necrosis
apoptosis involves decreased cell volume, chromatin condensation, DNA fragmentation, and membrane blebbling generating apoptotic bodies
**does not cause inflammation
44
Primary lymphoid tissues
Thymus and bone marrow
| -also known as the central lymphoid organs
45
Secondary lymphoid tissues
Lymph nodes, spleen, and mucosal associated lymphoid tissues (MALT)
46
GALT
Gut associated lymphoid tissue, where antigen is trapped.
- a specific type of MALT
- allows for interaction of antigen with mature lymphocytes and antigen dependant maturation of T and B cells
47
Tertiary lymphoid tissues
Normally contain fewer lymphoid cells than secondary organs but can import lymphoid cells during an inflammatory response
-eg. Cutaneous associated lymphoid tissue (CALT)
48
Thymus - outer cortex
packed densely with immature, proliferating thymocytes
| -most undergo apoptosis
49
Thymus - inner medulla
Sparsely populated with more mature thymocytes
50
During maturation, thymocytes interact with?
Cortical epithelial cells, medullary epithelial cells ,dendritic cells and macrophages
51
Thymus is the site of __ &__ maturation
T and NKT cell
52
____ lymphocytes circulate in the lymphatic vessels
mature
53
Lymphatic vessels drain back into circulation at:
The left subclavian vein via the thoracic duct
54
Afferent lymphatic vessels bring:
Lymph fluid containing antigen-carrying dendritic cells, particulate antigen, and a few lymphocytes from tissues to regional lymph nodes
55
Efferent lymphatic vessels bring:
Lymph fluid from the lymph nodes via the thoracic duct into venous circulation
- carry antibodies secreted by plasma cells and activated/memory T and B cells
- distribute effector cells and antibodies throughout the body
56
Lymph nodes are the site of:
Generation of T and B cell antibody responses to specific antigens
-lymphocytes interact with antigen/antigen presenting cells (especially interdigitating dendritic cells)
57
Lymph node structure: main features
- bean shaped
- sinuses (subcupscular, cortical medullary)
- afferent and efferent lymph vessels
- parenchyma comprised of cortex, paracortex, medulla
58
Lymph node: cortex follicles
1. Primary follicles: naive B cells, follicular dendritic cells, macrophages
2. Secondary follicles: activated B cells in germinal centres
59
Lymph node: paracortex
T cells, interdigitating dendritic cells
60
Lymph node: medulla
Phagocytic macrophages, antibody secreting plasma cells, some activated/memory B and T cells that are moving to efferent lymph
61
Lymph node: reticular network
Composed of extracellular matrix, reticular fibres and fibroblastic reticular cells
*provides support for lymphocyte compartments
62
High endothelial venules
Allow mature B and T lymphocytes to move from the blood into lymph nodes
63
Follicular dendritic cells
Located in the germinal center of lymph nodes
- concentrate antigen for B lymphocytes
- allow more B cell receptors to be occupied
64
Antigen dependent B lymphocyte maturation takes place in?
The lymph node
| -can only take place in 2º lymphoid tissues
65
Spleen structure: main features
- Located in the upper left quadrent of the abdominal cavity
- surrounded by a capsule
- has white pulp and red pulp surrounded by a marginal zone
66
Spleen: white pulp
Generation of T cell and B cell responses (antibodies) against blood borne antigens
67
Spleen: marginal zone
Interdigitating dendritic cells trap blood borne antigens and transport them to the white pulp
68
Spleen: red pulp
Defective and old RBC and blood borne pathogens are phagocytosed by macrophages
69
3 components of blood
RBC, WBC, Platelets
70
WBC of the blood (5):
```
Neutrophils
Monocytes
Lymphocytes
Eosinophils
Basophils
```
71
% Neutrophils in the blood
~70%
72
% lymphocytes in the blood
~20-40%
73
Neutrophils: production and lifetime
Produced in the bone marrow and released into the blood
Circulate for 7-10 hours
Generally first to arrive at sites of infection
-will die within 48 hours of migrating into tissue
74
Neutrophils: morphology
Segmented nucleus (up to 3-4) connected by chromatin strands
Has 2 types of granules
- primary: larger, denser, lysosomal function
- secondary: smaller
75
Neutrophils: size and count
~13µm in diameter
Most abundant leukocyte in the blood
- 2-8x10^9 cells/litre
- 50-70% of circulating leukocytes
76
Neutrophils: function
Phagocytosis of bacteria and debris
77
Neutrophils: 2 methods of killing ingested bacteria
1. Oxygen dependent: use of reactive oxygen intermediates
- superoxide anion
- hydroxyl radical
- hydrogen peroxide
- hypochlorite anion
2. Oxygen independent: use of reactive nitrogen intermediates
- defensins
- lysozyme
- hydrolytic enzymes
- tumor necrosis factor (TNF)
78
4 steps of Neutrophil migration
1. Tissue damage causes release of vasoactive and chemotactic factors that increase blood flow/capillary permeability
2. Permeable capillaries allow influx of fluid and cells
3. Phagocytes migrate to site of inflammation by chemotaxis
4. Phagocytes and antibacterial exudate (complement, C-reactive protein) destroy bacteria
79
Eosinophils: form, production, numbers
Produced in bone marrow and released into blood
Segmented nucleus (2 lobes)
Spherical granules
~12-17µm in diameter
~1-3% of blood leukocytes
80
Eosinophils: function
Anti parasitic function
-has a protein called eosinophil cationic protein (ECP)
Involved in allergic reactions
Contain lysosomal and oxygen radical generation enzymes like neutrophils
81
Basophils: form, production, numbers
Produced in bone marrow and released into blood
Segmented nucleus (2 lobes)
Spherical PURPLE granules
-contain histamine
~12-17µm in diameter
Make up
82
Basophils: Function
Back up mast cell responses in inflammation
Also involved in allergic reactions
Granules contain histamin
Also make leukotrienes and prostaglandins
83
Mast cells: production and differentiation
Produced in bone marrow and released into blood as immature precursor cells
Differentiate upon entering tissues
Usually found surrounding blood vessels and nerves
84
2 types of mast cells
1. Connective tissue mast cells
| 2. Mucosal mast cells
85
Mast cell: morphology
Similar to basophils but ARE NOT GRANULOCYTES
-they arise from different precursor cells
Heavily granulated
-contain histamine
~12-17µm in diameter
86
Mast cells: function
Initiators of inflammation
Involved in allergic reactions
Granules contain histamine
Also make leukotrienes, prostaglandins, and cytokines
87
Monocytes: morphology
Horse shoe nucleus
Bluish grey cytoplasm, often vacuolated
Variable # of fine reddish granules
~15-18µm in diameter
88
Monocytes: production and migration
Produced in the bone marrow and released into the blood
Circulate for ~8 hours
Migrate into tissues and differentiate into macrophages
89
Monocyte --> Macrophage differentiation
Increases 5-10 fold in size
Increases # of complex organelles
Increased phagocytic activity
increased levels of hydrolytic enzymes
90
Macrophage: function
Phagocytosis of microorganisms
-can grab bacteria with its pseudopodia
Killing of phagocytosed organisms through oxygen dependent and oxygen independent methods
Recruitment of cells to inflammatory site by releasing cytokines and chemokines
Presenting antigens to T cells
91
Macrophages are named according to?
Location.
-ex: alveolar, histiocytes (connective tissue), Kupffer cells (liver, mesangial cells (kidney), microglial (brain), osteoclasts (bone)
92
Initial activation of macrophages is due to?
Act of phagocytosis as well as Th1 cytokines like IFNy, inflammatory mediator and bacterial components
93
Activated macrophages exhibit what characteristics?
Enhanced phagocytic activity, killing ability, secretion of inflammatory mediators, the ability to activate T lymphocytes
94
Macrophages travel by ___ movement through the tissues
Amoeboid
95
Dendritic cells: production and migration
Produced in the bone marrow and released into blood
- all come from a common myeloid progenitor line that includes monocytes
* *except follicular dendritic cells
Migrate into tissues
96
Dendritic cells are the most potent form of what cell type?
Professional antigen presenting cells (APC)
| -unlike macrophages and B cells, DC don't have to be activated to do this
97
Dendritic cells load antigen onto which molecule(s) for presentation
Both MHC I and MHC II
98
Follicular dendritic cells
DON'T arise from bone marrow or act as APC
- located in lymph node follicles
- form important interactions with B cells in lymph node follicles
99
Dendritic cell: function
Capture antigens from invading pathogens in the tissues
Travel to the lymph nodes and present antigen to T cells (using MHC I and MHC II connecting to the TCR) and costimulate T cell activation
100
4 other forms of interaction between DC and T cells other than MHC
1. ICAM-1 to LFA-1
2. B7 to CD28
3. CD40 to CD40L
4. Cytokines released by the DC
101
Naive T and B cells: morphology
Round nucleus ~size of RBC
Small rim of blue cytoplasm
~9µm in diameter
**90% of lymphocytes
102
Large granular lymphocytes (NK and CTL)
Larger cell than T and B
More abundant cytoplasm
Larger granules
-contain perforin and granzyme
**10% of lymphocytes
103
Lymphocyte classification: T cells - %, ratios, and types
70-80% of lymphocytes
Made up of:
- CD4+ helper and regulatory T cells
- CD8+ cytotoxic T cells
* *CD4:CD8 = 2:1 ratio
104
Lymphocyte classification: B cells
Make up 10-20% of lymphocytes
105
Lymphocyte classification: NK cells
Make up 5-10% of lymphocytes
106
Lymphocyte classification: NKT cells
Express functional T cell receptors that interact with CD1 instead of class I and II MHC
107
Both NK and NKT cells function in ____ immunity
Innate
*both can produce cytokines
108
T cells and B cells function in ____ immunity
Acquired/adaptive
109
CD4+ T cells
Act as "generals" of the immune system
Help to activate CD8+ T cells, B cells, macrophages and other immune system cells
Regulate immune responses
Do so by producing a range of cytokines
110
CD8+ T cells
Kill virus infected cells and cancer cells
111
B cells: formation
Are formed AND mature in the bone marrow
Express membrane bound immunoglobulin
112
NK cells: formation
Form and mature in the bone marrow
*produce and secrete antibody
113
NKT cells: formation and role
Form in the bone marrow and mature in the thymus
Express T cell receptors
Kill virus infected cells and cancer cells
Important source of cytokines
