CELL MEDIATED IMMUNITY Flashcards
(161 cards)
1
Q
What is cell-mediated immunity (CMI)?
A
CMI is an immune response that does not involve antibodies but relies on T cells to fight infected or abnormal cells.
2
Q
Which type of immunity is mediated by T cells?
A
Cell-mediated immunity.
3
Q
What are the primary cells involved in cell-mediated immunity?
A
T cells (Cytotoxic T cells, Helper T cells), Macrophages, and Natura
4
Q
What is the function of a phagocyte in the immune system?
A
A phagocyte surrounds and engulfs particles or cells in a process called phagocytosis.
5
Q
What is phagocytosis?
A
Phagocytosis the process by which a phagocyte engulfs and digests pathogens or debris.
6
Q
What happens after a phagocyte engulfs a pathogen?
A
The pathogen is enclosed in a phagosome, which then fuses with a lysosome containing digestive enzymes to kill the pathogen.
7
Q
What roles do phagocytes play besides killing pathogens?
A
They also clean up debris and old cells.
8
Q
Why are phagocytes considered the first line of immunological defense?
A
Because they respond quickly to pathogens as part of the innate immune system.
9
Q
What is the first step in the phagocytosis process?
A
Chemotaxis and adherence of the microbe to the phagocyte.
10
Q
What receptors help macrophages recognize foreign particles?
A
Pattern Recognition Receptors (PRRs) detect Pathogen-Associated Molecular Patterns (PAMPs) on microbes.
11
Q
What structure forms after a phagocyte engulfs a microbe?
A
A phagosome, which is a vesicle containing the ingested microbe.
12
Q
How is the microbe digested inside the phagocyte?
A
The phagosome fuses with a lysosome, forming a phagolysosome, where digestive enzymes break down the microbe.
13
Q
What happens to the indigestible material after microbial digestion?
A
It forms a residual body and is later expelled as waste.
14
Q
What are the key steps in the phagocytosis process?
A
- Chemotaxis & adherence
- Ingestion of the microbe
- Formation of a phagosome
- Fusion with a lysosome (phagolysosome formation)
- Digestion by enzymes
- Formation of a residual body
- Exocytosis (discharge of waste)
15
Q
Which cells have phagocytic ability?
A
Macrophages, neutrophils, and dendritic cells.
16
Q
Describe the shape and movement of a macrophage.
A
Irregularly shaped and amoeboid in nature, allowing them to move through tissues and squeeze through capillary walls.
17
Q
What is the role of macrophages in the immune response?
A
They participate in innate immune responses and cooperate with lymphocytes of the adaptive immune response.
18
Q
Where can macrophages be found in the body?
A
They can exist freely roaming or fixed to reticular fibers of specific tissues.
19
Q
What is the first line of defense when pathogens breach the body’s barrier defenses?
A
Macrophages.
20
Q
What are Kupffer cells?
A
A type of macrophage found in the liver.
21
Q
What are histiocytes?
A
A type of macrophage found in connective tissue.
22
Q
Where are alveolar macrophages located?
A
In the lungs.
23
Q
What is a monocyte?
A
A circulating precursor cell that differentiates into either a macrophage or dendritic cell.
24
Q
What attracts monocytes to areas of infection?
A
Signal molecules of inflammation.
25
What is the primary location of macrophages?
Body cavities/organs.
26
What is the primary location of neutrophils and monocytes?
Blood.
27
What is the function of macrophages in the innate immune response?
Phagocytosis.
28
What is the function of neutrophils in the innate immune response?
Phagocytosis.
29
What is the function of monocytes in the innate immune response?
Precursor of macrophage/dendritic cell.
30
What type of cell is a neutrophil?
A phagocytic cell.
31
How are neutrophils attracted to infected tissues?
Via chemotaxis.
32
Describe the shape of neutrophils.
Spherical
33
Are neutrophils granulocytes or agranulocytes?
Granulocytes
34
What are cytoplasmic granules?
Membrane-bound enzymes and other mediators within the cytoplasm of granulocytes.
35
Give an example of a vasoactive mediator found in granulocytes.
Histamine
36
What is the function of natural killer (NK) cells?
To induce apoptosis in cells infected with intracellular pathogens.
37
What is apoptosis?
Programmed cell death.
38
What type of cells are NK cells?
Lymphocytes.
39
What is the cascade of events inside the cell called?
Apoptosis
40
How do NK cells respond to chemical signals?
By expressing the Fas ligand.
41
What does the Fas ligand bind to?
The Fas molecule on the surface of the infected cell.
42
What happens after the Fas ligand binds to the Fas molecule?
It sends apoptotic signals, killing the cell and the pathogen within.
43
What is one method by which cytotoxic T cells induce their targets?
Apoptosis (cell suicide).
44
What type of cells are targeted by cytotoxic T cells?
Virus-infected cells.
45
What do granules of NK cells release?
Perforins and granzymes.
46
What is perforin?
A protein that forms pores in the membranes of infected cells.
47
What is granzyme?
A protein-digesting enzyme that enters the cell via perforin pores and triggers apoptosis intracellularly.
48
Against what type of cells are both perforin and granzyme mechanisms especially effective?
Virally infected cells.
49
What do phagocytic cells and cytotoxic NK cells recognize?
Patterns of pathogen-specific molecules.
50
What are examples of pathogen-specific molecules recognized by phagocytic cells and NK cells?
Bacterial cell wall components or bacterial flagellar proteins.
51
How do phagocytic cells and NK cells recognize pathogen-specific molecules?
Using pattern recognition receptors (PRR).
52
What is a pattern recognition receptor (PRR)?
A membrane-bound receptor that recognizes characteristic features of pathogens and molecules.
53
What releases PRRs?
Stressed or damaged cells.
54
What are soluble mediators?
Chemical signals that can induce cells to change various physiological characteristics.
55
What is an example of a physiological characteristic changed by soluble mediators?
Expression of a particular receptor
56
When are soluble factors secreted?
During innate or early induced responses, and later during adaptive immune responses.
57
What is a cytokine?
A signaling molecule that allows cells to communicate with each other over short distances.
58
Where are cytokines secreted?
Into the intercellular space.
59
What is the action of a cytokine on a receiving cell?
It induces the receiving cell to change its physiology.
60
What is a chemokine?
A soluble chemical mediator similar to cytokines, but its function is to attract cells (chemotaxis) from longer distances.
61
What is the main function of chemokines?
To attract cells (chemotaxis).
62
What is the main function of cytokines?
To allow cells to communicate with each other over short distances.
63
What are the T-cell effector subgroups listed?
Th1, Th2, Th9, Th17, Cytotoxic T lymphocyte.
64
What cell products are associated with Th1 cells?
Interferon-γ (IFN-γ).
65
What cell products are associated with Th2 cells?
Interleukin-4 (IL-4), Interleukin-5 (IL-5), Interleukin-13 (IL-13).
66
What cell products are associated with Th9 cells?
Interleukin-9 (IL-9), Interleukin-10 (IL-10).
67
What cell products are associated with Th17 cells?
Interleukin-17 (IL-17), Interleukin-21 (IL-21), Interleukin-22 (IL-22).
68
What cell products are associated with Cytotoxic T lymphocytes?
Interferon-γ (IFN-γ), Perforin, Granzyme.
69
What is the main function of IFN-γ?
Recruitment and cytotoxicity.
70
What cell types are targeted by Th1 cells?
Macrophages, Dendritic cells.
71
What cell types are targeted by Th2 cells?
Eosinophils, Basophils.
72
What cell types are targeted by Th9 cells?
Mast cells.
73
What cell types are targeted by Th17 cells?
Neutrophils.
74
What cell types are targeted by Cytotoxic T lymphocytes?
Virally infected cells.
75
What is the function of cytotoxic T cells (CD8+)?
They directly kill virus-infected cells, tumor cells, and intracellular pathogens.
76
How do helper T cells (CD4+) assist in cell-mediated immunity?
They release cytokines to activate macrophages and cytotoxic T cells.
77
Front: When are early induced proteins made?
Back: As they are needed early during the innate immune response.
78
Front: Give an example of an early induced protein.
Back: Interferons.
79
Front: What cells secrete interferons?
Back: Cells infected with viruses.
80
Front: What do interferons do?
Back: Travel to adjacent cells and induce them to make antiviral proteins.
81
Front: Name two early induced proteins made in the liver.
Back: Mannose-binding protein and C-reactive protein.
82
Front: What do mannose-binding protein and C-reactive protein bind to?
Back: Polysaccharide components of the bacterial cell wall.
83
Front: What cells have receptors for mannose-binding protein and C-reactive protein?
Back: Phagocytes such as macrophages.
84
Front: What does the binding of mannose-binding protein and C-reactive protein enhance?
Back: Phagocytosis of the bacterium (opsonization).
85
Front: What is opsonization?
Back: The tagging of a pathogen for phagocytosis by the binding of an antibody or an antimicrobial protein.
86
What is the role of opsonins?
Back: To enhance phagocytosis by making pathogens more recognizable to phagocytic cells.
87
Front: What is the complement system?
Back: A series of proteins found in the blood plasma.
88
Front: Where are complement proteins made?
Back: In the liver.
89
Front: What is the "alternate pathway" of the complement system?
Back: A pathway that does not require an antibody.
90
Front: What is the "classical pathway" of the complement system?
Back: A pathway of the adaptive immune response that requires antibodies.
91
Front: What happens to complement proteins during activation?
Back: Several proteins enzymatically alter and fragment in a series (cascade).
92
Front: Is the series of reactions in the complement system reversible or irreversible?
Back: Irreversible.
93
Front: What happens when complement proteins bind to the cell membrane of a pathogen?
Back: They label it for phagocytosis (opsonisation).
94
Front: What do complement proteins act as?
Back: Chemotactic agents to attract phagocytic cells to the site of inflammation.
95
Front: What do complement proteins form in the plasma membrane of the pathogen?
Back: Damaging pores.
96
Front: What is the first step in the classical pathway shown in the image?
Back: C1 binds to an antigen-antibody complex on an invading pathogen.
97
Front: What happens after C1 binds in the classical pathway?
Back: It causes cleavage of components C2 and C4 into fragments.
98
Front: What forms the C3 convertase in the classical pathway?
Fragments from C2 and C4 combine.
99
Front: What does C3 convertase split into?
Back: C3a and C3b.
100
Front: What is the role of C3b in the classical pathway?
Back: Binds to the surface of the pathogen.
101
Front: What does C5 convertase split into?
Back: C5a and C5b.
102
Front: What forms the membrane attack complex (MAC)?
Back: Fragments from C5 join C6, C7, C8, and C9.
103
Front: What does the membrane attack complex (MAC) do?
Back: Forms pores in the pathogen's plasma membrane, causing water to rush into the cell and leading to lysis.
104
Front: What is the hallmark of the innate immune response?
Back: Inflammation.
105
Front: What triggers inflammation?
Back: Tissue damage (e.g., stub a toe, cut a finger).
106
Front: What are the four characteristics of inflammation?
Back: Heat, redness, pain, and swelling.
107
Front: What do mast cells detect in the inflammatory response?
Back: Injury to nearby cells.
108
Front: What do mast cells release in response to injury?
Back: Histamine.
109
Front: What does histamine initiate?
Back: The inflammatory response.
110
Front: What does histamine increase during inflammation?
Back: Blood flow to the wound sites.
111
Front: What does increased blood flow bring to the wound sites?
Back: Phagocytes and other immune cells.
112
Front: What do phagocytes and other immune cells do at the wound site?
Back: Neutralize pathogens.
113
Front: What does the blood influx cause at the wound site?
Back: Swelling, redness, warmth, and pain.
114
Front: Why is the adaptive immune response important even when innate responses occur?
Back: Innate responses are often ineffective at completely controlling pathogen growth.
115
Front: What are two roles of the innate immune response in relation to adaptive immunity?
Back: Slow down pathogen growth and allow time for the adaptive immune response to strengthen.
116
Front: What is the ultimate goal of the adaptive immune response?
Back: To either control or eliminate the pathogen.
117
Front: What does the innate immune response do in terms of the adaptive immune system?
Back: Sends signals to the cells of the adaptive immune system, guiding them in how to attack the pathogen.
118
Front: What is the primary adaptive immune response?
Back: The immune system's first exposure to a pathogen.
119
Front: What is the secondary adaptive immune response?
Back: The immune response upon re-exposure to the same pathogen.
120
Front: How does the secondary adaptive immune response compare to the primary response?
Back: Stronger and faster than the primary response.
121
Front: What does the secondary adaptive immune response often do before significant tissue damage or symptoms?
Back: Eliminates the pathogen.
122
Front: What is the basis of immunological memory?
Back: The secondary adaptive immune response.
123
Front: What does immunological memory protect us from?
Back: Getting diseases repeatedly from the same pathogen.
124
Front: How does the antibody concentration in the secondary response compare to the primary response?
Back: It is significantly higher.
125
Front: What is an important feature of the adaptive immune response?
Back: Its ability to distinguish between self-antigens and foreign antigens.
126
Front: What happens as T and B cells mature?
Back: There are mechanisms that prevent them from recognizing self-antigens.
127
Front: What is the purpose of preventing T and B cells from recognizing self-antigens?
Back: Preventing a damaging immune response against the body.
128
Front: What are the primary cells that control the adaptive immune response?
Back: Lymphocytes, specifically T and B cells.
129
Front: What do T cells control?
Back: A multitude of immune responses that is control B cell immune responses in many cases.
130
Front: What type of decisions do T cells make about pathogens?
Back: Many decisions about how to attack a pathogen.
131
Front: How do T lymphocytes recognize antigens?
Back: Based on a two-chain protein receptor.
132
Front: What is the name of the T cell receptor?
Back: Alpha-beta T cell receptors.
133
Front: How many types of receptors does each T cell produce?
Back: Only one type of receptor.
134
Front: What is the specificity of each T cell?
Back: Specific for a single particular antigen.
135
Front: What are the two chains of the T cell receptor called?
Back: Alpha and beta chains.
136
Front: What regions are present in each chain of the T cell receptor?
Back: Constant and variable regions.
137
Front: What anchors the T cell receptor to the cell membrane?
Back: The transmembrane region.
138
Front: What is the function of the variable region of the T cell receptor?
Back: To bind to a specific antigen.
139
Front: What is the function of the constant region of the T cell receptor?
Back: To provide structural stability and interact with other molecules.
140
Front: What are antigens generally like in terms of size and complexity?
Back: Usually large and complex.
141
Front: What are antigens composed of?
Back: Many antigenic determinants.
142
Front: What is an antigenic determinant (epitope)?
Back: One of the small regions within an antigen to which a receptor can bind.
143
Front: What limits the size of an antigenic determinant?
Back: The size of the receptor itself.
144
Front: What is the typical size of an antigenic determinant in a protein?
Back: Less than 6 amino acid residues.
145
Front: What is the typical size of an antigenic determinant in a carbohydrate antigen?
Back: 1-2 sugar moieties.
146
Front: Where are carbohydrate antigens found?
Back: Bacterial cell walls and red blood cells (ABO blood group antigens).
147
Front: How would you describe protein antigens?
Back: Complex.
148
Front: What is a characteristic of the shapes of protein antigens?
Back: Variety of three-dimensional shapes.
149
Front: For what types of immune responses are protein antigens especially important?
Back: Immune responses to viruses and parasites.
150
Front: What does the image show about a typical protein antigen?
Back: It has multiple antigenic determinants.
151
Front: What does the image show about T cells and antigenic determinants?
Back: T cells with different specificities bind to different parts of the same antigen.
152
Front: Why are protein antigens important for immune responses against viruses and parasites?
Back: Because they are complex and have a variety of three-dimensional shapes, allowing for specific recognition by the immune system.
153
Q: What is the role of cytotoxic T cells in CMI?
A: Cytotoxic T cells destroy virus-infected cells, tumor cells, and cells with intracellular pathogens.
154
Q: How do helper T cells (CD4+) contribute to CMI?
A: They release cytokines that activate macrophages, cytotoxic T cells, and other immune responses.
155
Q: What is the major histocompatibility complex (MHC), and why is it important in CMI?
A: MHC is a set of cell surface proteins essential for recognizing antigens and activating T cells.
156
Q: What are cytokines, and what role do they play in CMI?
A: Cytokines are signaling molecules that regulate immune responses, including activation of T cells and macrophages.
157
Q: What is the difference between cell-mediated and humoral immunity?
A: Cell-mediated immunity involves T cells targeting infected cells, while humoral immunity involves antibodies produced by B cells.
158
Q: How do macrophages participate in CMI?
A: Macrophages present antigens to T cells and release cytokines to enhance immune responses.
159
Q: What is the role of natural killer (NK) cells in cell-mediated immunity?
A: NK cells kill infected or cancerous cells without prior sensitization.
160
Q: How does memory in T cells enhance cell-mediated immunity?
A: Memory T cells allow for a quicker and stronger response upon re-exposure to the same pathogen.
161
