Lecture 26/27: Lymphoid Flashcards
(150 cards)
1
Q
What does CD stand for? What does it mean?
A
Cluster of differentiation: a particular cell type displays some cell surface marker that is useful for identification purposes
2
Q
What is necrosis?
A
When a cell bursts and dies in an uncontrolled process
3
Q
What cleans up the mess after necrosis?
A
Macrophages
4
Q
What does necrosis cause?
A
An inflammatory response because the cell membrane ruptures and spills cellular contents into the milieu
5
Q
What is apoptosis?
A
Cell suicide in a controlled process
6
Q
What can induce apoptosis?
A
Fas ligands
7
Q
What are the body’s 3 lines of defense? In order.
A
- Physical/biochemical barriers 2. Innate/non-specific immunity 3. Adaptative/specific immunity
8
Q
Describe the body’s physical/chemical barriers. Examples?
A
Obstacles to prevent pathogens from gain foothold on/in body: sloughing off skin cells, acidic pH in stomach and reproductive system, flushing of urinary tract, tears, mucus, cilia, commensals (bacteria to help with digestion)
9
Q
Describe the innate/non-specific immunity.
A
Evolutionary primitive defense mechanism
10
Q
Does the innate/non-specific immunity have immunologic memory?
A
NOPE
11
Q
When does the innate/non-specific immunity join the fight?
A
When a pathogen enters the body
12
Q
Describe adaptive/specific immunity.
A
More recent evolutionary development charged with discriminating between biological components that are self and non-self
13
Q
What are the 3 basic characteristics of adaptive/specific immunity that distinguish it from innate/non-specific immunity?
A
- Specificity 2. Diversity 3. Memory
14
Q
What are the 2 mechanisms of adaptive immunity?
A
- Humoral: B-cell mediated 2. Cellular: T-cell mediated
15
Q
How does the number of Natural Killer cells change after a surgery? When is this most severe? What does this do?
A
Considerably decreases in number and function Most severe 3 days post-op Makes it easier for metastatic cells to seed new locations
16
Q
What is the suppression of NK cells proportional to?
A
The extent of the surgical intervention
17
Q
Describe humoral adaptive immunity.
A
- Antigen presented to B lymphocyte 2. B cell surface antibody reacts with antigen 3. B cell undergoes clonal expansion 4. B cell proliferates to form 2 different cell types: plasma cells and memory B cells
18
Q
What is another name for B cells?
A
B lymphocytes
19
Q
Describe how the plasma cell created by the B cell works.
A
It has lots of RER to secrete soluble antibodies
20
Q
For how long does the plasma cell created by the B cell survive?
A
Weeks - months
21
Q
How can one recognize a plasma cell histologically?
A
Large cytoplasm filled with RER
22
Q
Is the memory B cell terminally differentiated?
A
NOPE
23
Q
Is the plasma cell terminally differentiated?
A
YUP
24
Q
What is the purpose of the memory B cell?
A
Produce a rapid response if the same antigen is presented again
25
Do the memory B cell lose its proliferative potential?
NOPE
26
Where do B cells go once they are released by the bone marrow?
Lymph nodes and spleen
27
Where do stem cells destined to become T cells go once they are released by the bone marrow?
Thymus where they mature
28
What happens to the thymus as you get older?
It atrophies
29
Describe the structure of IGs.
2 heavy chains + 2 light chains connected by disulfide bonds
30
What is the purpose of the variable portions of an IG? Where are they located?
Provides a certain degree of specificity for antigens On each heavy chain and each light chain (at the tip of the Y)
31
Where does the variable portions of IGs come from?
Somatic recombination: 3 different exons coding for heavy and light chains shuffle in order to code for novel combinations of variable portions of the antibody
32
What does the DNA coding for heaving and light chains consist of?
1. Variable-region exons 2. Joining-region exons 3. Diversity-region exons
33
What are the 5 types of IGs?
1. IgG 2. IgM 3. IgA 4. IgD 5. IgE
34
What are the 3 functions of IgGs?
1. Opsonization
2. Neutralization
3. Protect newborn
35
Which are the first antibodies to be produced in an initial immune response? Ie: which IGs constitute the primary response?
IgMs
36
What IG is dominant in the secondary response?
IgG
37
Which lag is longer: lag between exposure and primary response or lag between recurrent exposure and secondary response?
Lag between exposure and primary response
38
What is the function of IgAs? How come?
Protect the surface of mucosas as they resist proteolysis because tagged with a "secretory component" to protect itself from lysosomal degradation within the epithelial cell while being transcytosed through it (removed for it to become fully functional again)
39
What is the function of IgDs?
Receptors to antigens triggering B cell activation
40
What are the 2 functions of IgEs?
1. Participate in allergies 2. Lyses parasitic worms
41
What 3 Igs are monomers?
1. IgG 2. IgD 3. IgE
42
What Ig is a pentamere?
IgM
43
What Ig is a dimer with a secretory component?
IgA
44
Which Ig is the secretory one? Across what is it secreted?
IgA secreted across lining epithelium
45
Where is IgA made? Example?
Plasma cells in MALT: lining of GI tract, lungs (pleural cavity), tonsils
46
What do all 5 types of Igs have in common?
All have same core structure of 2 heavy and 2 light chains
47
What are the 5 ways in which antibodies engage pathogens?
1. Agglutination 2. Opsonization 3. Neutralization 4. Cytotoxicity 5. Complement activation
48
Describe agglutination.
Antibody binds antigen = fewer antigens
49
Describe opsonization.
Antibody binds antigen = antigen marked for phagocytosis
50
Describe neutralization.
Antibody binds antigen = blocks their pathogenic adhesion mechanisms + inactivates their toxins
51
Describe cytotoxicity.
Antibody binds parasitic worms = induces macrophages and eosinophils to inondate the worm with chemical agents
52
What are CD8+ T cells also called?
Cytotoxic T-cells
53
What are CD4+ T cells also called?
Helper T-cells
54
How is the T cell activated?
When the T cell receptor on the surface of T cells interacts with an antigen presented on an MHC (major histocompatibility complex)
55
What type of T cell does MHC 1 interact with?
Cytotoxic T cells
56
What type of T cell does MHC 2 interact with?
Helper T cells
57
What is another name for cytotoxic T cells?
Cytotoxic lymphocytes
58
What happens when the cytotoxic T cell is presented an antigen on MHC 1?
Memory T cells and cytotoxic T cells are produced
59
What do cytotoxic T cells do to the virally infected cells of the body? 2 options.
1. They use perforin to lyse infected cells 2. They use Fas ligand to initiate apoptosis of the infected cell
60
What happens when the helper T cell is presented an antigen on MHC 2?
Helper T cell activated and produces interleukins inducing B cells to become active and proliferate/differentiate
61
What is a potential therapy for a patient who has severe combined immunodeficiency (no B or T cells)? What are the risks?
Viral vectors = gene threapy
Have oncogenic risks though because these would randomly enter the genome and sometimes disrupt other normal genes
62
What does the HIV virus do?
Destroys HELPER T cells: titer declines during latency period until reaching a critical level where infections occur and lead to death
63
What type of antibodies on the B lymphocytes recognize antigens that are presented?
IgDs
64
What are the 3 cell types in innate immunity? List what each includes.
1. Mastocytes
2. Granulocutes: neutrophils and eosinophils
3. Agranulocytes: monocytes, macrophages, NK lymphocytes
65
What is the function of mast cells?
They participate in innate immunity and liberate compounds that modulate inflammation.
66
What do NK lymphocytes do?
Destroy pathogens
67
What is this?
Natural Killer cell
68
How can one reduce surgical stress? Purpose?
Robotic surgery to not decrease too many NK cells
69
What is the oldest vertebrate class that had adaptive immunity? What does it include?
Sharks with immunoglobulins, gene rearrangement mechanisms, T cell receptors, and MHCs
70
What are the 2 functions of the lymphoid system?
1. Recognize antigens
2. Inactive/Eliminate antigens
71
What are the 4 types of antigens?
1. Foreign material
2. Microorganisms
3. Cancer cells
4. Organ transplants
72
Where does the synthesis of B cells and T cells start?
Bone marrow
73
Where do B cells mature?
Bone marrow
74
Where are B cells produced during the 2 trimester of pregnancy?
Fetal liver
75
Which is the most common Ig?
IgG
76
What are these?
Plasma cells (from B cells)
77
Where are IgEs located?
Surface of mastocytes and basophils
78
Where are IgMs located as monomers?
Surface of B cells
79
What is the production of T cells stimulated by?
Cytokines secreted by basophils, B cells, macrophages, hassal's corpuscles in thymus
80
Describe complement activation.
Antibody binding to initial protein of complement system = complement cascade = produces membrane attack complex with transmembrane channels to cause cell lysis
81
What is another name for cytokines?
Lymphokines
82
What is PD-1?
A cell surface receptor on T cells which down-regulate the immune system by preventing the activation of T cells
83
What are PD-1's ligands?
PDL-1 and PDL-2
84
What do PD-1 inhibitors do? What are they used to treat?
Activate the immune system to attack tumors = used to treat cancer
THIS IS INHIBITING THE INHIBITOR
85
What were the 6 milestones of cancer discoveries?
1. Surgery (helped with robotics and anesthetics)
2. Radiation therapy
3. Hormonal therapy
4. Chemotherapy
5. Gene therapy
6. Immunotherapy
86
What are supressor T cells?
T cells with PD-1 receptors
87
What are examples of APCs?
Macrophages, dendritic cells, langerhans cells, osteoclasts ...etc
88
Does apoptosis create an immune response?
NOPE
89
What is a side effect of HIV drugs?
Accelerated aging
90
What are the 2 types of lymphoid organs?
1. Central
2. Peripheral
91
What is the lymphoid system responsible for?
Surveying the body for pathogens and producing immune cells
92
What is the central lymphoid system made of? What do these two have in common?
1. Thymus: site of T cell maturation
2. Bone marrow: site of B cell maturation
They are both encapsulated
93
What does encapsulated mean?
Surrounded by connective tissue
94
Where do B and T cells go once they mature in the central lymphoid organs?
The peripheral lymphoid organs
95
What are the 2 types of peripheral lymphoid organs? List what each includes.
1. Encapsulated: lymph nodes and spleen
2. Unencapsulated: single nodules, aggregated nodules, diffuse lymphoid tissue, MALT
96
What is the role of the encapsulated lymphoid organs?
Filtering the 2 types of fluid found in the body:
* Lymph nodes: lymph
* Spleen: blood
97
What is MALT? What % of all lymphoid tissue does it comprise? What is its role?
Mucosa Associated Lymphoid Tissue
85%
Conducts antigen surveillance along mucosal tracts: lungs, GI tract, reproductive tract, oral cavity
98
What are nodules?
Unencapsulated group of lymphocytes (peripheral lymphoid organ)
99
Describe the B and T cell composition of the lymph nodes.
* B cells in cortical nodules = superficial cortex
* T cells in paracortex
100
Describe the B and T cell composition of the spleen.
* B cells in lymphoid nodules
* T cells in PALS = PeriArterial Lymphatic Sheath
101
Describe the lymphocyte composition of the blood.
[T cell] \>\>\>\> [NK cells] \> [B cell]
102
Describe the B and T cell composition of the lymph.
[T cell] \>\>\>\> [B cell]
103
Describe the B and T cell composition of the mucosal tissues = unencapsulated perypheral lymphoid organs.
[B cell] \>\>\>\> [T cell]
104
Are the B and T cells localized in specific spots in the blood, lymph, and mucosa?
NOPE
105
Where is diffuse lymphoid tissue found?
Small intestine
106
What are the 4 components of diffuse lymphoid tissue?
1. Lamina propria
2. Lymphocytes (mainly B)
3. Eosinophils
4. Plasma cells
107
What is the lamina propria?
The connective tissue that lines the mucosa underneath the surface epithelium
108
What is another name for solitary nodules?
Follicles
109
Where are solitary nodules found?
* Lymph nodes
* MALT
110
What are the 2 types of solitary nodules? What does each contain? How does each stain?
1. **Primary nodules:** naive B cells
⇒ one color density w/ H&E
1. **Secondary nodules:**
* Cap/Mantle: naive B cells (around germinal center stains darker)
* Germinal center (two color density w/ H&E because more sytoplasm): activation of immune cells:
* B cells
* Helper T cells
* Dendridic cells
* Tingible bodies
111
What do tonsils contain? What is around them?
Germinal centers, which are greater in number during an oral infection
* At bottom: the cap
* At top: non-keratinized epithelium
112
Where are Peyers patches found? What do they contain? What are they used for? Describe how this works.
Found in lamina propria of the ileum of the small intestine, contaning primary nodules
Used for antigen surveillance: M/Microfold cells between surface epithelial cells of the small intestines transport the antigen to lymphocytes inside the Peyer's patch (eg: macrophages for stimulation of B and T cells)
113
What are the 3 aggregated nodules?
1. Tonsils
2. Peyers patches
3. Vermiform appendix
114
Describe the encapsulation of aggregated nodules.
Incomplete = considered unencapsulated
115
What are the 4 capsulated lymphoid organs?
1. Bone marrow
2. Spleen
3. Lymph nodes
4. Thymus
116
What are solitary nodules?
Aggregation that is not surcomscribed to connective tissue capsule
117
What are diffuse lymphoid tissues? Where are these usually found?
Cluster of lymphocytes (typically found in the mucosa)
118
What is the order of complexity of lymphoid organs?
1. Circulating Lymphocytes
2. Diffuse Lymphoid Tissues
3. Solitary Nodules
4. Aggregated Nodules (incompletely encapsulated)
5. Specific Organs (encapsulated)
119
Where is the Vermiform appendix located? How does it change as a person ages?
McBurney's point
The amount of immune tissue inside it declines, adipose replaces
120
What is the main function of the thymus?
T cell maturation
121
What are the 2 major components of
122
Where do T cells mature in the thymus?
Begin to mature in cortex and continue to be modified in the medulla
123
What are the epithelial reticular cells of the thymus?
Cells that form the microframework of the thymus and act as a scaffolding for T cells to hang on while they mature
124
What % of T cells are self-recognizing? How do we protect them from attacking us?
95% (VERY INEFFICIENT)
Blood-thymus barrier which separates the processes in the thymus from causing problems to the rest of our bodies + they are not released and destroyed
125
What are Hassal's corpuscles? What do they secrete?
Remnants of keratinized epithelial reticular cells located in the thymus (medulla) ONLY
Secrete cytokines to promote chemotaxis
126
Label this shit.
127
How does the number of T cells in the thymus change with age? What is this called?
Decreases and replaced with adipose tissue
Thymic involution
128
What are the 3 immune organs that are replaced with adipose tissue with age?
1. Bone marrow
2. Thymus
3. Appendix
129
What are the 4 functions of the lymph nodes?
1. Filter lymph
2. Antigen surveillance
3. Recognize activated lymphocytes in the blood
4. Release more lymphocytes in the blood during infection
130
How many lymph nodes do we have in our body? What are they in line with?
\>500
Lymph vessels
131
Why are lymph nodes biopsied for? What sometimes happens to them?
Tumor cell metastasis to look for tumor cell-related surface markers
Surgeons will remove them after removing a tumor if cancer cells are suspected there
132
What are 3 areas of the body that are rich in lymph nodes?
1. Neck
2. Mediastinum (central compartment of the thoracic cavity)
3. Retroperitonium
133
What is the pathway of the lymphatic fluid as it travels through the lymph node? 5 steps
Show it on the image.
1. Afferent lymphatics
2. Subcapsular sinus
3. Trabecular sinus
4. Medullary sinus
5. Hilium/Efferent lymphatics
134
Does blood travel through the lymph nodes? How?
Yes, but in the opposite direction as the lymph:
Post-Capillary High Endothelial Venules (HEVs) in the paracortex are made of cuboidal cells (rather than squamous), which allows lymphocytes in the blood to squeeze between them to activate other lymphocytes in the lymph nodes
135
What are the 4 functions of the spleen?
1. Filtering blood
2. Mounting immuse responses against pathogens in blood
3. Storing platelets
4. Performing hematopoiesis (residual function from fetus) if damaged bone marrow
136
Describe the passage of blood through the spleen.
1. Central artery or arteriole
2. White pulp
3. Marginal zone sinuses
4. Red pulp: splenic cords
5. Red pulp: venous sinusoids
6. Hepatic portal vein
137
What is the white pulp of the spleen composed of?
Lymphocytes:
* B cells in lymphoid nodules (periphery of white pulp)
* T cells in PALS
138
How does white pulp stain? Why?
Dark purple because lymphocyte nuclei
139
What is included in the marginal zone?
Lymphocytes
140
What are the 2 parts of the red pulp of the spleen?
1. Splenic cords
2. Venous sinusoids
141
How does the red pulp of the spleen stain? Why?
Lighter because of RBCs that do not have nuclei
142
What are the 3 functions of the splenic cords?
1. Platelet storage
2. Iron storage
3. Hematopoiesis
143
What to note about the central artery?
It's NOT CENTRAL in the white pulp
144
Describe the marginal zone sinuses.
Very loose blood vessels without muscles
145
What happens as blood goes through the venous sinusoids? Describe the 2 types of circulations.
Older or sickled RBCs are filtered out by macrophages
**2 circulations:**
1. Open: 90% of flitration, SLOW: Direct contact between blood and sinusoid parenchyma
2. Closed: 10% of filtration, FAST: Discontinuity between blood and sinusoid parenchyma
146
Where are the PALS in the spleen?
Around the perimeter of the central artery
147
What must all RBCs pass before going back into the blood? Purpose?
Sinusoidal wall
Only healthy cells can pass
148
Where is somatic recombination seen in lymphocytes?
* Variable portions of Igs made by B cells
* T cell receptors
149
What can be said of all peripheral lymphoid organs?
They contain lymphoid nodules
150
