Adaptive Immunity Flashcards
(137 cards)
1
Q
Define Adaptive Immunity
A
Protection provided by immune responses that improve due to exposure to antigens.
2
Q
What cells are involved in adaptive immunity?
A
B and T cells
3
Q
What is an antibody?
A
Y-shaped protein that binds antigens
4
Q
What is an antigen?
A
Molecule that reacts specifically with either an antibody or an antigen receptor on a lymphocyte.
5
Q
What does APC stand for?
A
Antigen-Presenting Cells
6
Q
What is an APC?
A
Cells such as dendritic cells, B cells, and macrophages that can present exogenous antigens to T cells.
7
Q
What is a B cell?
A
A type of lymphocyte programmed to make antibody molecules.
8
Q
What does CMI stand for?
A
Cell-Mediated Immunity
9
Q
What is Cell-Mediated Immunity (CMI)?
A
Immunity involving a T-cell response.
10
Q
What is Clonal Selection?
A
Process in which lymphocyte’s antigen receptor bind to an antigen, allowing the lymphocyte to multiply.
11
Q
What is a Cytotoxic T Cell?
A
Type of lymphocyte programmed to destroy infected or cancerous “self” cells.
12
Q
What is a Dendritic Cell?
A
Cell type responsible for activating naive T cells.
13
Q
What is an Effector Lymphocyte?
A
Differentiated descendant of an activated lymphocyte; its actions help eliminate antigen.
14
Q
What is a Helper T Cell?
A
Type of lymphocyte programmed to activate B cells and macrophages and assist in other parts of the adaptive immune response.
15
Q
What is Humoral Immunity?
A
Immunity involving B cells and an antibody response.
16
Q
What are lymphocytes?
A
A group of white blood cells (leukocytes) involved in adaptive immunity; B cell and T cells are examples.
17
Q
What does MHC molecules stand for?
A
Major Histocompatibility Complex Molecules.
18
Q
What do Major Histocompatibility Complex (MHC) Molecules do?
A
Host cell surface proteins that present antigens to T cells.
19
Q
What are Major Lymphocytes?
A
Long-lived descendants of activated lymphocytes that can quickly respond if a specific antigen is encountered again.
20
Q
What is a Plasma Cell?
A
Effector form of a B cell.
21
Q
What does a Plasma Cell do?
A
It functions as an antibody-secreting factory.
22
Q
What is a Tc Cell? (Not what is does.)
A
Effector form of a cytotoxic T cells.
23
Q
What does a Tc Cell do? (Not what it is)
A
It induces apoptosis in infected or cancerous “self” cells.
24
Q
What is a Th Cell? (not what it does)
A
Effector form of a Helper T Cell.
25
What does a Th Cell do? (not what it is)
It activates B cells and macrophages and releases cytokines that stimulate other cells of the immune system.
26
What population did diphtheria target?
infants and small children
27
What were the symptoms of diphtheria?
The first symptom was a sore throat followed by the development of a gray membrane that could come loose and block the airway.
28
Who (2 people) discovered diphtheria antitoxin by injecting the antitoxin with serum and injecting into guinea pigs?
Alexandre Yersin and Emile Roux
29
How long does adaptive immunity take to build after exposure to a given antigen?
A week or more.
30
Define Immune Tolerance.
Decreased reactivity of the immune system to a specific antigen.
31
What is a "self" cell?
It simply means being within one of the body's own cells. For example, viruses and some bacteria that replicate within a self cell.
32
Where does the "T" of T Lymphocytes and T Cells come from?
It stems from the fact that they mature in the "Thymus".
33
What does "Humor" mean as in "Humoral Immunity"?
Humor means "fluids".
34
Where does the "B" in B Lymphocytes and B cells come from?
Because these cells develop in the "Bone" marrow of mammals.
35
What do naive T cells proliferate into?
Tc Cells
36
What do Tc Cells "deliver"?
Death packages or apoptosis for infected "self" cells.
37
What do naive helper T cells proliferate into?
Th Cells
38
What do Th Cells "deliver"?
Cytokines to macrophages, increasing their killing power.
39
What do naive B cells proliferate into?
Plasma cells that produce antibodies (Humoral)
40
What is the functional difference between B cell receptors (BCRs) and T Cell receptors (TCRs)?
T cell receptors only bind antigens presented by another cell; B cell receptors bind only free antigents (Humoral)
41
How is a B cell receptor similar to an antibody?
They are both humoral. As in the both only bind free antigens as opposed to binding to infected cells.
42
How does Central tolerance prevent inappropriate immune responses?
This takes place as lymphocytes mature (T cells in the Thymus and B cells in the Bone marrow); it eliminates immature T and B cells found to recognize certain "self" molecules.
43
Hoes does Peripheral Tolerance prevent inappropriate immune responses?
This occurs after lymphocytes mature; it prevents any T and B cells not eliminated during Central tolerance from reacting against self or other harmless molecules.
44
What is a naive lymphocyte?
A mature lymphocyte that has not encountered antigen previously.
45
What cells are responsible for the effectiveness of the secondary immune response?
Memory Lymphocytes
46
What is the difference between the primary and secondary immune responses?
The primary immune response is the first response to a particular antigen, developing the first immunity; the secondary immune response occurs after the same antigen is encountered again, resulting in a much faster and more effective reaction thanks to memory Lymphocytes.
47
What cells of the adaptive immune system can best be likened to "emergency lights"? And why?
Dendritic cells. They produce co-stimulatory molecules if the antigen is microbial or otherwise dangerous. It travels to regions where naive T cells gather to "warn" them in this way.
48
What cell only specifically targets infected self cells to cause apoptosis?
Tc Cells
49
Which type of adaptive immunity cells are specifically involved in Humoral Immunity?
B cells
50
How are naive B cells activated?
If Th Cells (Effector helper T cells) binds to an antigen and delivers it to naive B cells thereby activating it. If naive B cells encounter an antigen that binds to B-Cell receptors (BCR), the B cell takes up that antigen, degrades it, and presents the pieces to Th Cells.
51
Where do Y-shaped antibodies come from?
They are secreted proteins of the effector (or activated) B cell receptors (BCRs) called plasma cells.
52
How do antibodies protect against the effects of antigens?
1. They target it for elimination
2. They coat an antigen so that it can no longer bind to host cells
53
What's a Fab region?
The top Y-shaped portion of an antibody that attaches to antigens.
54
What is an Fc region?
The bottom stem portion of the Y-shaped antibody that tags the antigen for rapid elimination.
55
How are antibodies and the compliment protein C3b similar?
They both opsonize antigens.
56
What does "immunogenic" mean?
Immunogenic is used to describe the relative ability of an antigen to elicit an immune response.
57
What are epitopes?
Also called antigenic determinants. They are the sites on an antigen that BCRs and TCRs bind. They are generally simplified to just "antigen" rather than "epitope of an antigen".
58
Explain hematopoietic cells.
The cell in the bone marrow from which all blood cells, including lymphocytes, stem from--a hematopoietic stem cell.
59
What are the primary lymphoid organs?
1. Bone Marrow
2. Thymus
60
Give 3 examples of secondary lymphoid organs.
1. Lymph nodes
2. spleen
3. tonsils
4. Peyer's patches
5. mucosal tissues
6. cryptopatches
7. Isolated Lymphoid Follicles (ILFs)
61
What is the function of secondary lymphoid organs with regards to adaptive immunity?
An organized structure center for various immune cells to interact and transfer cytokines. They also capture antigens from lymph (filter) and bring them into contact with dense populations of lymphocytes.
62
What are Peyer's patches?
A type of secondary lymphoid organ that resides in the intestinal walls, inspecting antigens in the intestine. An important member of mucosa-associated lymphoid tissue (MALT).
63
How is the cell-mediated response different from the humoral response? (microassessment 15.1)
Cell-mediated response involves T cells; humoral response involves B cells.
64
Why is it important that T cells and B cells become activated before they can begin multiplying in response to an antigen? (microassessment 15.1)
An inactive T and B cell is called a naive cell and is not yet and effector; that is that I cannot bind to an antigen until it has first been activated.
In order for T and B cells to be capable of responding to an antigen, they typically require a signal from another cell first. Without this signal, T and B cells typically remain naive and ineffective against a specific antigen.
65
How would you expect a Tc cell to respond if it encountered a Th cell that was infected with a virus? (microassessment 15.1)
If a cytotoxic T cell (Tc) encounters a helper T cell (Th) that is infected with a virus, the Tc cell will recognize the viral antigen presented on the infected Th cell's surface and induce apoptosis (programmed cell death) in the infected Th cell, effectively killing it to eliminate the virus from the body.
66
Explain the clonal selection theory.
The immune system can respond to a seemingly unlimited range of antigens by using a pre-existing and preprogrammed population of lymphocytes, each one recognizing a specific epitope on an antigen. The theory states that only lymphocytes that encounter their given antigen can multiply. Thus, the antigen determines which lymphocytes multiply.
67
To help you remember what clonal selection theory is, come up with a good analogy as a memory bridge. See the answer to have one provided, but also feel free to use your own!
A lymphocyte is looking for its one and only soul-mate (epitope of antigen) to marry (bind to) before starting family. (multiplying)
<3
68
How does a naive lymphocyte differ from an active one? (microassessment 15.2)
A naive lymphocyte is a fully mature cell that has not encountered the specific antigen that it is programmed to respond to.
An active lymphocyte is a naive lymphocyte that has encountered the specific antigen and they have received the necessary signals confirming that the antigen means "danger." An active lymphocyte is able to multiply and proliferate.
69
What would happen if the body lost the ability to make memory lymphocytes? (microassessment 15.2)
"Immunity" to an antigen would cease to exist for that person.
70
What are major Histocompatibility complex (MHC) molecules?
Proteins on the surface of host cells that those cells use to present antigen peptide fragments to T cells.
71
Cytotoxic T cells only recognize antigens presented on what class of MHC molecule?
MHC class I molecules
72
Helper T cells only recognize antigens presented on what class of MHC molecules?
MHC class II molecules
73
Which T cell type recognizes peptide fragments presented on MHC class I molecules?
Cytotoxic T cells
74
Which T cell type recognizes peptide fragments presented on MHC class II molecules?
helper T cells
75
Cytotoxic and helper T cells are identical microscopically. Which CD (cluster of differentiation markers) are typically associated with helper T cells?
CD4 markers
76
Cytotoxic and helper T cells are identical microscopically. Which CD (cluster of differentiation markers) are typically associated with cytotoxic T cells?
CD8 markers
77
What cells do dendritic stimulate?
T cells, using co-stimulatory molecules on both MHC class I and class II molecules.
78
Which types of cells produce MHC class II molecules for inspection by Th cells?
1. Dendritic cells (MHC class I and class II, co-stimulatory)
2. B cells
3. macrophages
79
What is the crucial difference between MHC class I and MHC class II molecules?
MHC class I are from endogenous antigens
MHC class II are from exogenous antigens
With the exception of cross-presentation by dendritic cells during T cells activation, MHC class I molecules are used to present antigens made by the self cells (endogenous antigens), MHC class II molecules are used to present antigens taken up by the self cell from it's surrounding environment (exogenous antigens).
80
During chronic inflammation, when regular macrophages are unable to kill microorganisms, macrophages activate and fuse together forming ______ ______.
Giant Cells
81
What are giant cells and why are they formed?
Giant cells are activated macrophages that have fused together. They can form granulomas when regular macrophages are unable to kill a microorganism--like is found in the case of Mycobacterium tuberculosis.
82
In the case of most antigens, B cells are required to be activated by what?
Th Cells
83
Cytotoxic/CD8 T cells recognize antigen peptide fragments on what molecules?
MHC class I molecules
84
What is the effector form of cytotoxic/CD8 T cells?
Tc Cell
85
What are potential targets for cytotoxic/CD8 T cells?
All nucleated cells
86
What are Tc cell's function?
Induces a target cell to undergo apoptosis.
87
What is the source of peptide recognized by Tc cells?
Endogenous antigen (produced within the target cell)
88
Helper/CD4 T cells recognize antigen peptide fragments on what molecule?
MHC class II molecules
89
What is the effector form of helper/CD4 T cells?
Th Cells
90
What are the potential targets for helper T cells (CD4)?
1. B cells
2. macrophages
91
What is the function of Th cells?
Activates a target cell. Either B cells or macrophages.
92
What is the source of peptide recognized by Th cells?
Exogenous antigens (produced outside of the target cells)
93
If an effector CD8 cell recognizes antigen presented on an MHC class I molecules, how should it respond? (microassessment 15.3)
A Tc (CD8) cell should:
1. induce apoptosis in the target cell that presented the MHC class I molecule
2. produce cytokines that increase the level of surveillance.
94
If an effector CD4 cell recognizes antigen presented on an MHC class II molecules, how should it respond? (microassessment 15.3)
Th (CD4) cells should:
1. activate the target cell that presented the MHC class II molecule (B cells and macrophages)
2. secrete cytokines that orchestrate the immune response
95
Why would a person who had AIDS be more susceptible to the bacterium that causes tuberculosis (Mycobacterium tuberculosis)?
AIDS directly affects and infects CD4 T cells, which play a crucial role in orchestrating the adaptive immune response. Without enough functional CD4 (Th) T cells, the body struggles to mount an effective immune response against many pathogens, including M. tuberculosis.
96
What happens if no Th cells recognize the peptides presented by a B cell?
That B cell may become anergic.
97
What is another word for immunoglobulins?
antibodies
98
What are the 5 classes/isotopes of immunoglobulin molecules?
1. IgM
2. IgG
3. IgA
4. IgD
5. IgE
Remember "GAMED".
99
What percentage of serum antibodies are IgM?
5-13%
100
How are IgM antibodies unique?
They are pentamer, as in composed of five Y-shaped subunits, making them particularly large. They also have 10 identical antigen-binding sites making them effective at cross-linking antigens.
101
Where are IgM antibodies typically found? Why?
In the blood stream as they are too large to cross from the bloodstream into tissues. Due to this, they primarily control bloodstream infections.
102
Which is the most abundant antibody isotope?
IgG
103
What percentage of serum antibodies are IgG?
80-85%
104
Which antibody class provides the longest-term protection?
IgG
105
Which antibody class can cross the placenta?
IgG
106
Which antibody class is found in mucus and accounts for mucosal immunity?
IgA, more specifically secretory IgA (sIgA)
107
What percentage of serum antibodies are IgA?
10-13%
108
What percentage of serum antibodies are IgD?
<1%
109
What are the responsibilities of IgD?
Development and maturation of the antibody response.
110
What percentage of serum antibodies are IgE?
It is barely detectable.
111
Where are IgE antibodies found?
They are rarely in free circulation, instead they are tightly bound via the Fc region to basophils and mast cells, allowing these cells to detect and respond to antigens.
112
Which antibody class is associated with histomine release and allergies?
IgE
113
Which antibody class is found in breast milk and protects the intestinal tract of breast-fed infants?
IgA
114
B cells that are most effective at binding antigen are most likely to proliferate and, in turn, the plasma cells that descend from these cells secrete antibodies that bind the antigen more effectively. This is a form of natural selection among proliferating B cells, what is the term for this?
Affinity maturation
115
Explain "class switching" of B cells.
All B cells initially differentiate into plasma cells that secrete IgM. As the activated B cells multiply, however, some are induced to switch that genetic program through loss of DNA, causing them to differentiate into plasma cells that secrete other antibody classes. B cells in the lymph nodes most commonly switch to IgG production. B cells in the mucosa-associated lymphoid tissues generally switch to IgA production, providing mucosal immunity.
116
What is the primary immune response?
Initial exposure to an antigen.
The first detectable levels of IgM production begins.
A germinal center (GC) is established in a secondary lymphoid organ.
Affinity maturation occurs over generations of plasma cells.
Class switching among B cells.
Memory B cells begin forming.
117
What is the Secondary Immune Response?
Second, or more, exposure to an antigen.
Because of memory lymphocytes, the secondary immune response is much faster and more efficient than the primary immune response.
IgG antibodies accumulate quickly.
Often the secondary immune response occurs without the host being aware that anything happened.
118
What is a T-dependent antigen?
B cells that bind to them cannot be activated without a Th cells interaction.
119
What are T-independent antigens?
B cells binding to them can be activated without the assistance of Th cells.
120
Are gram-negative bacteria a t-dependent or t-independent antigen?
t-independent
121
Describe the significance of class switchig. (microassessment 15.4)
They allow a swift and more effective secondary immune response.
122
How does the ability to bind antigen increase as B cells multiply? (microassessment 15.4)
B cells proliferate into plasma cells that produce antibodies. B cells also bind to antigens, stimulating an activation response from Th and B cells. The more B cells available, the higher the antibody concentration. B cells only begin to decrease once there are no more antigens to bind and thereby stimulating B cell multiplication.
123
Why should B cells residing in the mucosa-associated lymphoid tissues produce IgA?
Because secretory IgA (sIgA) is capable of existing outside the body, and in many other mucus membranes like the intestines, tears, and saliva, creating a powerful mucosal immunity.
124
Aside from Th and Tc Cells, what is a recently described third type of T cell?
T reg Cells, or Regulatory T Cells
125
What is neutralization?
The coating and "neutralizing" of viruses and toxins. Preventing them from being able to attach to cells and damaging them.
126
Which type of cell is primarily responsible for antibody-dependent cellular cytotoxicity (ADCC)?
Natural killer (NK) cells
127
What is difference in effect between the binding of antibodies on flagella and pili?
The binding of flagella prevent the bacteria from moving. The binding of pili prevent the bacteria from attaching to surfaces.
128
How many polypeptide chains make up a T cell's receptor?
2, it is similar to a single branch of a "Y" antibody in the Fab region.
129
How long does it take after naive B cells are activated to produce a substantial amount of antibodies?
10 - 14 days, or up to 2 weeks.
130
CD4+ is related to what cell?
helper T Cell
131
What are the 4 subsets of Th cells?
1. Th1
2. Th2
3. Th17
4. Tfh (follicular)
132
What do the cytokines produced by Th1 cells do?
Activate macrophages and stimulate Tc cells
133
What do the cytokines produced by Th2 cells do?
Recruit eosinophis and basophils against multicellular pathogens.
134
What do the cytokines produced by Th17 cells do?
Recruit neutrophils, directing a response against extracellular pathogens.
135
What do the cytokines produced by Tfh (follicular) cells do?
Promote an effective humoral response.
136
How many heavy chain molecules are found in an antibody?
2
137
