Immunology Lecture 1 Flashcards
1
Q
Cells of the immune system travel through…
A
The circulatory(blood) and lymphatic system(lymph)
2
Q
True/False: Immune system protects the body at all times?
A
True
3
Q
Immune system protects from…
A
Pathogens: Bacteria, viruses and parasites
Altered body cells: Cancer
4
Q
Ture/False: Immune system reaches everywhere?
A
True
5
Q
What are the two prongs of the immune system?
A
Non-specific/Innate
Specific/Adaptive
6
Q
Are you born with both systems of the immune system?
A
Yes
7
Q
Of the two prongs of the immune system which is the first-line of defence?
A
The non-specific/innate branch
8
Q
Which prong of the immune system recognizes pathogens?
A
Specific/Adaptive immunity
9
Q
What happens when the non-specific branch sees a pathogen for the second time?
A
Nothing! It has the same response each time it sees a pathogen no matter what kind of pathogen it is
10
Q
What is a leap of faith?
A
Type of dicovery where we make an observation than take it a step further by testing a hypothesis
11
Q
How was small pox a leap of faith?
A
Edward jenner noticed milk maids didnt contract small pox but had pock marks on their hands. The milk maids were contracting cow pox which was making them immune to small pox. He took a leap of faith by injecting pus from a cow pox lesion under the skin of a healthy individual. This prevented the person from getting small pox
12
Q
What is serendipity?
A
Type of discovery
“Happy Accident”: when something goes wrong, we look into greater detail and maybe find a new discovery
13
Q
What was discovered via serendipity?
A
Penicillin
14
Q
Examples of accident of nature?
A
HIV
SCIDS
15
Q
What SCIDS?
A
Patients do not have a functional immune system
16
Q
What is HIV?
A
HIV is due to a loss of the T helper cells, this prevents activation of B cells and T cells preventing the activation of an adaptive immune response
17
Q
What three components make up the immune system?
A
- Lymphoid organs
- Immune cells
- Secretions of immune cells
18
Q
What occurs at the primary lymphoid organs?
A
Stem cells divide and immune cells develop
19
Q
What type of organs make up the primary lymphoid organs?
A
- Bone Marrow(prior to birth this yolk sac, fetal liver and fetal spleen)
- Thymus
20
Q
What happens in the bone marrow?
A
-All blood cells are produced here(B cells and T cells)
-B cells mature here
21
Q
What happens in the thymus?
A
-T cells mature here (travel to the thymus after being birthed in the bone marrow)
-Above the heart
- Contains phagocytic cells(dendritic, macrophages)
-Atrophies (old age thymus almost gone)
22
Q
What occurs in the secondary lymphoid organs?
A
Immune response occurs here between pathogens and immune cells
23
Q
What organs make up the secondary lymphoid organs?
A
- Lymph nodes
- Spleen
- Lymphoid Nodules
24
Q
What is the role of the lymph nodes?
A
- Filter microbes
Macrophages in nodes phagocytixe microbes that enter lymph
25
What is the role of the spleen?
-Largest organs
-Removes/filters microbes and old erythrocytes with phagocytic cells
26
What makes up the lymphoid nodules?
- Tonsils
-MALT(Mucosal-Associated Lymphoid Tissues)
-Peyer's Patch
-Appendix
27
How do immune cells travel through the body?
In the blood and lymph
28
Is the capillary more permeable to bacteria than the lymphatic system?
NO! The lymphatic system os more permeable just as it is with proteins
29
What type of cells are immune cells?
Leukocytes/White blood cells(lack hemoglobin)
30
Are all immune cells derived from the same cell?
Yes, they are all derived from the pluripotent hematopoietic stem cell in the bine marrow
31
What cells are porduced via the lymphoid lineage?
Lymphocytes that becomes T cells, B cells and NK cells
32
What type of T cells exist and what protein do they carry on their surface?
1. T helper cells have CD4+
2. Cytotoxic T-cells have CD8+
3. Regulatory T-Cells have CD4+
33
What are the granulocyte immune cells?
1. Eosinophils - destroy parasites
2. Basophils - Release histamines and prostaglandins
3. Mast Cells - Release histamines
34
What is the most numerous white blood cell?
Neutrophils - phagocytes
35
What do monocytes become?
Macrophages
Dendritic Cells
36
What is the first-line of defense in the non-specific branch of the immune system?
Physical barriers
37
What is the second-line of defense in the non-specific branch of the immune system?
Cellular factors
Humoral factors
38
What is the role of the first-line of defense barriers?
Keep pathogens from reaching our tissue & creating an unpleasant environment that discourages growth
39
Name some of the physical and mechanical
barriers
1. Tight junctions in epithelia (separates apical and basal fluids)
2. Mucus(hard for bacteria to move)
3. Hair and Cilia
4. Skin (water resistant, prevents entry of foreign substances)
40
Name chemical and microbiological barriers?
Enhance the barriers
1. Secretions: Sebum(low pH), Lysozymes(breaksdown bacterial cell walls) and gastric juice(low pH)
2. Normal flora (protects from bacteria overgrowth)
41
What happens when the first-line of defense in the non-specific branch is breeched?
The second line of defense in the non-specific will be used
42
What makes up the humoral factors of the second line of defense?
1. Inflammation
2. Antimicrobial Substances
3. Interferons
43
What are the 4 signs of inflammation?
1. Redness (increse blood flow)
2. Heat (increased blood flow)
3. Pain (tissue damage/ factors released)
4. Swelling (fluid moves into tissue)
44
What are the 3 stages of inflammation?
1. Vasodilation
2. Emigration of phagocytes
3. Tissue repair
45
What is vasodilation
widening of blood vessels allows more blood to flow to the site of injust also results in increased permeability of capillaries which allows substance to go to the damaged site
46
What humoral substances are produced?
1. Interferons
2. Complement
3. Iron-binding proteins
47
How do viruses replicate?
Viruses move into a cells inject themselves into the cell and then generate copies of themselves. This then leads to the cell bursting and new viral particles infecting other cells
48
What does type I interferon do ?
Prevents viral replication
49
How does type I interferon work?
1. Infected cell with the virus starts to produce type I interferons in response to being infected
2 . All cells have type I interferon receptors on their surfaces. Uninfected cells will recieve the type I interferon signal
3. This signal tells cells to produce antiviral proteins
4. Now if the cell becomes infected with the viral particle it will be able to prevent its replication
50
What is complement?
Family of plasma proteins of 30 proteins that participate in the cascades C3b
51
How does C3b work?
It will move out into the tissue where bacteria are present, it then binds to the surface of the bacteria. Phagocytes have C3b receptors, they will then bind to the C3b and then easily engulf the molecule
52
What is opsonization?
Prepares the pathogen for eating
53
What do iron-binding substances do ?
When we have a bacterial infection the body responds by releasing more transferrin which will bind to any available iron and sequester it from bacteria that need it to divide
54
What are the cellular factors?
1. Natural killer cells
2. Phagocytic cells (neutrophils, macrophages, dendritic)
3. Cells with inflammatory mediators (granulocytes)
55
How are NK cells similar to cytotoxic T cells and different ?
Similar:
- Attack/kill cells directly after binding
Different:
- NK cells are NOT antigen specifc
56
How do NK cells kill infected cells?
They release perforin (makes a pore in cell membrane) and granzymes (go through the pores into the cell)
57
Which cells express MHC-1 on their surface?
Nucleated body cells
58
Do RBCs express MHC-1?
No because they are not nucleated
59
How do NK cells recognize infected cells?
If NK cell binds to MHC-1 it will recieve a negative signal and will not bind NK activating ligand to kill cell
If NK does not bind to MHC-1, NK activating ligand will bind and cause the release of granzymes/perforin
60
Types of phagocytes?
Fixed-tissue macrophages -already in tissue
Neutrophils - recruited to site of injury
Monocytes - become macrophages and dendritic cells
61
What are the steps of phagocytosis?
1. Adherence (microbe sticks)
2. Ingestion (microbe put in a membrane bound compartment(phagosome))
3. Digestion(phagosome fuses to lysosome that destroys bacteria)
4. Killing (death of microbe)
62
How do phagocytes recognize microbes?
Microbes have PAMPs(pathogen assocaited molecular patterns) on their surface that are recognized by PRRs(Pattern recognition receptor) which are found on the surfaces of phagocytes
63
What is a Toll-Like Receptor?
A type of Pattern recognition receptor(PRR) found on the macrophage phagocyte
64
Describe the structure of a toll-like receptor?
- HAs an intracellular signaling domain
-Has an extracellular domain that recognizes PAMPs of pathogens
65
When do macrophages TLRs bind to pathogens PAMPs?
As so as the skin has been breeched and bacteria has entered the skin, macrophages bind to the PAMPs with their TLRs
66
What does the binding of PAMPs to TLRs do ?
Sneds a signal(cytokines) to tell the body there is an infection. These signals cause inflammation and recruitment of other types of phagocytes to fight the infection
67
In inflammation what is the emigration of phagocytes?
Phagocytes come are recruited to the site of injusry and help clean up bacteria
68
What is chemotaxis?
movement of phagocytes along a gradients of a tissue
69
What is chemokine/chemoattractants?
Chemicals that attract phagocytes
70
What is margination?
endothelial cells in the region of the tissue damage become stickier which allows neutrophils to stick
71
What is diapedesis?
Phagocytes move across the capillary wall and out into the tissue
72
What do neutrophils do in inflammation?
-Die in the process of killing bacteria
- Rlease their NETs
73
What is NETs?
Neutrophil Extracellular Traps
come from neutrophils, consists of a lot of sticky components, creates a mesh network that traps bacteria and prevents them from moving to other parts of the tissue
74
What is pus?
A mixture of dead bacteria and neutrophils
75
What is recruited after neutrophils die?
Dendritic cells
76
What does the dendritic cell do?
Kills and transports bacteria to the regional lymph node
- When it kills the bacteria it will put some of it on its surface
77
What is an antigen?
-A material that stimulates an immune response
-Antibody generator
- Can be a whole cell or a part of a cell
-Can be non-microbial (pollen, egg whites, incompatible blood cells, transplanted tissues)
ex. Immunogen, allergen, ligand
78
What is an epitope?
Part of the antigen that is recognized by the antibody
79
How do dendritic cells travel to the lymphonode from the tissue?
Lymphatic vessels
80
Why are all MHC molecules unique?
MHC - I and MHC- II both have three genes unsed to make them resulting in unique MHC in people
81
What people have the same MHCs ?
Identical twins
82
Where are MHC-II cells expressed?
Only on antigen-presenting cells
ex. Macrophages, dendritic cells, b-cells
83
True or False: T-cell receptors only recognize antigens when they are associated with MHC II proteins?
True
84
How do antigen presenting cells express antigen with MHC II?
1. Ingest antigen
2. Digestion into peptide fragments
3. Synthesize and package MHC-II molecules
4. Bind peptide fragment to MHC-II
5. Insert antigen-MHC-II complexes on plasma membrane
85
True/False: B/T cells must recognize the specific foreign material to be attacked?
True
86
What is the humoral aspect of the specifc immune branch?
It is the B cells
- Transform into plasma cells and produce/secrete antibodies
- Use antibodies and complement to kill
87
What is the cell-mediated portion of the specifc immune branch?
Cytotoxic T cells
- Attack infected body cells, cancer cell , foreign cells
88
How are the lymphocytes activated?
B cells, T cells are activated by recognizing the specific antigen that binds to their receptor
T helper cells are also need to activate B cells and cytotoxic T cells
89
What is the double recognition event?
T-helper cell is only activated once MHC-II binds to CD4 and B7 binds to CD28
90
What is the first recognition event?
Specific recognition:
MHC-II of APC binds to CD4 on T helper
91
What is the second recognition event?
Co-reception:
B7 of APC binds to CD28
92
How can the T cell be inactivated?
CTLA4 and PD-1 are upregulated when T-cell have been active a while. CTLA4 will replace the binding of CD28 which turns off activation
93
How can the inactivation/ activation of T cells be used to help kill cancer cells?
T-cells specfically cytotoxic T cells helps kill cancer cells which is why we want them active all of the time. Scientists have found a way to generate antibodies that bind to CTLA4 and prevent it from binding to B7 which results in the T cell always being active
94
How are B cells activated?
1. Receptor on surface recognized antigen
2. Helper T cells with the same receptor for the antigen will release cytokines that fully activate the B cell
95
How do B cells activate T helper cells?
B cells can phagocytose antigens and then present them on their surface with an MHC II protein. This can help activate T-helper cells
96
What type of cells do B cells produce when activated?
Plasma cells(produce antibodies)
Memory B cells(long-lived)
97
What do antibodies produced by B cells do ?
Fight infection
98
What is in the plasma cell and how long does it last?
- Full of ER because its only function is to make antibodies
- Only live 7-10 days
99
What shape is an antibody?
Y shaped
100
What is the structure of a antibody?
-Antibodies are made up of four polypeptide chains(two light and tow heavy)
-Variable region(FAB) - this is unique in every antibody and determines which antigen will bind
- Constant regions(Fc) - this is the same in all antibodies of the same class(found at the end of the Y)
101
What protein group are antibodies part of?
Globulins, specifically immunoglobulins
102
What is the IgG class?
- 2 binding sites
-monomer
-smaller - move through the body easy
-most numerous
-Second antibody formed in a none MALT response
103
Which antibody class can cross the placenta and give antibodies to the baby?
IgG
104
What is the IgA class?
- Dimers
-4 binding sites
-Found in secretory tissues/MALT
-Second antibody formed if infection is in MALT
105
What class of antibodies is found in breast milk and passes through GI tract of babies?
IgA
106
Why is IgA class so good in MALT?
Can cross mucous barrier
107
What is the IgM class?
-10 binding sites
-First antibody formed
-Best at activating complement
108
What is IgD and IgE?
IgD: prenatal
IgE: involved in allergies
109
Where do B cells get activated?
Secondary lymphoid organs: spleen, lymphoid nodule or lymph node in the prescence of a microbe
110
What is clonal selection?
Carried out by activated B cells: It the process of only cells with the specifc receptor being activated to produce plasma cells and memory cells
111
What is active antibody-mediated immunity?
Resistance due to the body's contact with microorganisms, toxins or other antigenic components
Results in long lasting protection(memory cells)
112
How can active anitbody-immunity be natural vs artificial?
Natural - Develops with natural exposure to the antigen (someone sneezes on you)
Artificial - Develops with purposefule exposure to an antigen (immunization)
113
What is passive antibody-mediated immunity?
The person recieves antibodies from another person or animal
This is temporary protection and does not result in production memory cells
114
How can passive anitbody-immunity be natural vs artificial?
Natural: IgG from mother to fetus across the placenta or IgA from breast milk
Artificial : Recieve a serum containing anntibodiesfrom a person/animal
115
What is neutralizing antigen?
An antibody function where antibodies bind to the toxin antigen and prevent them from finding and binding to cells
116
What is agglutinating antigen?
An antibody function where the antibody binds to the pathogen and makes it harder for them to move through the tissue and divide, this also makes it easier for phagocytes to find them
117
What is precipitating antigen?
An antibody function where the antibody binds to the pathogen and now it can no longer function or move freely
118
What is activating complement?
An antibody function where the antibody-antigen binding recruits the C1 complement, which results in the activation of complements C2-C9. Complements C5-C9 form a pore in the surface of the bacteria (membrane attack complex). These pores lead to bacteria death (causes contents to lyse out and cell to die)
119
How does antibody tagging for phagocytosis work?
Phagocytes have Fc receptors for the antibody. When an antibody binds to an antigen the phagocyte will be bound to the antibody and then will eat the antibody
120
Do natural killer cells participate in both branches of the immune system?
Yes
121
How do Natural killer cells participate in the adaptive branch?
NK cells express receptors for Fc on their surface. When a NK cells binds to an antibody bound to an antigen this stimulates the release of granzymes and perforin by the NK cell
122
How can NK cells kill cancer cells?
Produce an antibody specific to the tumor cell and then give it to a patient. NK cells will then bind to the antibody and kill the infected cell.
123
What is clonal expansion?
The expansion of lymphocytes with a specfic receptor
124
True or False: More lymphocytes means a more rapid response?
True
125
Describe antibody production the first time we see an antigen
1. After a few days of the exposure the body starts to produce antibodies
2. By 1 week: we are at peak antibodies
3. After 1 week: plasma cells exhaust/die and number of antibodies decreases
4. But now we have more memory cells
126
How will the body respond differently the second time it sees an antigen its. already seen?
The body will have a much faster immune response due to memory cells (clonal expansion)
The first time we saw the antigen we probably got sick but the second time we saw it we may not have
127
If you are immunized for influenza a but you get influenza b do the memory cells of influenza a result in a more rapid response?
NO
128
What is the second class of antibodies produce?
IgG or IgM it depends on if the infection is in the mucosal tissues
129
What is immunocompetence and what needs this?
Lymphocytes need to gain immunocompetence in order to develop antigen receptors
130
How does a lymphocyte gain immunocompetence?
Through a process of recombination of the D, J and V genes
131
True or False: The b cell receptor will be identical to the secreted antibodies from the plasma cells
True
132
What is the role of RAGs in immunocompetence?
Recombination activating genes splicr out different gene segements from the V, D and J genes
133
What is the role of TdT in immunocompetence?
Terminal deoxynucleotidyl transferase increases the variety of receptors by adding single nucleotide at the junctions between gene segments
134
Does the body create antibodies to self antigens?
NO
135
What is immune tolerance and when does it occur?
Immune tolerance is clonal deletion or inactivation of cells that match body antigens. It occurs the during the fetal and early postnatal life
136
What is T cell tolerance?
1. T cells must recognize MHC class II molecules
2. T cells should not recognize self-proteins or cells expressing MHC class-I
If either of these conditions are not met T cells eill br negatively selected(killed)
137
How is the cytotoxic T cell activated?
1. By its specific antigen by binding to MHC class I with the antigen to the cytotoxic t-cell receptor
2. By the helper T cells release of cytokines
138
What is the difference between cytotoxic T cells and T helper cells?
Cytotoxic T cells:
- Recognize endogenous antigens (antigen that are produced by the body cells)
-Infected body cells have an antigen-MHC I complex on its plasma membrane that cytotoxic T cells recognize
T helper cells:
- Recognize exogenous antigens (foreign material from outside the body)
-Antigen presenting cells have an antigen-MHC II complrx on its plasma membrane for T helper cells to recognize
139
Exogenous vs Endogenous antigens?
Exogenous antigens enter from the outside of the body (bacteria , fungi, protazoa)
Endogenous antigens are found within the cytosol of the human cells (tumor, viral proteins)
140
How do cytotoxic T cells kill infected cells?
Cytotoxic T cells will find infected cells bind to them and then release perforin and granzymes which kill the infected cells
141
Does the cytotoxic T cell also have the ability to be turned off by CTLA4?
Yes
142
How does a protein-calorie malnutrition affect infection resistance?
Althoug you are borin with the B & T lymphocytes, if you mount an immune response all of these active cells need to divide and produce antibodies. This requires a lot of raw materials which come from food.
143
What is the greatest contributor to decrease resistance to infection worldwide?
Protein-calorie malnutrition
144
How do preexisting diseases affect infection resistance?
Can make a person inclined to infection
145
Dhoes stress and state of mind affect infection resistance?
Yes, they can either enhance or redues resistance to infection and cancer
146
Does sleep depravation affect infection resistance?
Yes, sleep depravation is associated with a decrerase immune function
147
How does exercise and physical conditiong affect the immune system?
Has a net beneficial effect on immune system and host resistance
148
What is the cause of immunodeficiency diseases?
Results from a weak, underactive, or impaired immune system
149
What is SCID?
An immunodefieciency disease where the immune system has an abscence of both B and T cells and NK cells
150
What is HIV ?
An immunodefieciency disease where the helper T cells are infected and killed resulting in an impaired immune response
151
Why do tissue grafts and organ transplants mount an immune response?
MHC class I proteins on graft cells and MHC class II proteins on macrophages are seen as foreign by the recipients cells. The recipeints Tc cells wih the aid of TH cells kill cells bearing the foreign MHCs
152
How is transplant rejection avoided?
-Drugs that kill actively divind lymphocytes are given (decreases the recipients T cell population)
153
What does cyclosporine do and why is it given to a person?
Cyclosporine is given to a recipient of a tissue graft/organ transplant this drug blocks cytokine production from T helper cells which eliminated signals for proliferation of helper and cytotoxic T cells
154
What is hemolysis?
Destruction of erythrocytes during a blodd transfusion
155
How are RBCs recognized as foreign if they have no MHC proteins?
Erythrocytes have membrane proteins and carbohydrates on their surfaces that function as antigens
156
What determines blood class?
The ABO system of carbohydrates
157
What type of blood can type A recieve?
Type A canrecieve O and A and has an antibody in blood for B
158
Why is O the universal donor?
Because it does not have A or B as an antigen
159
Why is AB the universal recipient?
Because AB blood does not have antibodies for A or B
160
How does giving birth to an Rh positive baby as an Rh negative mother affect the fetus?
The mother will give birth to the first baby and at birth if her blood mixes with the baby her blood will develop an antibody again Rh positive blood. If she gets pregnant again with an Rh positive baby those antibodies will destroy the fetus
161
What is an allergic reaction?
when a person is reactive to a substance that most others tolerate well
- They are usually restricted to the site of injury
162
Name the two types of allergic reactions?
1. Immediate hypersensitivity
2. Delayed hypersensitivity - appears 12-72 hours after allergen exposure
163
What is anaphylaxis?
- If large amounts of mast cell histamine enter the circulation, severe hypotenstion and bronchiolar constriction occur
-Can cause death due to circulatory and respiratory failure
164
What does the mast cell do during anaphylaxis?
Releases too much histamine into the blood stream which causes anaphylaxis
165
What is an autoimmune disease?
when body proteins act as antigens
166
Why do autoimmune diseases occur?
We don't know. Often they arise later in life and could be caused by a cell now expressing a new protein or by T cells that were not killed during early development
167
Role of regulatory T cells?
Inactivate self reactive T cells later in life
168
What branch of cells is involved in the innate branch of the immune system?
Myeloid branch
169
