Chapter 1 7 Flashcards
Adaptive Immunity
1
Q
Vaccination
A
An immunity to disease by exposure to a harmless version of pathogens that mimic the adaptive response of the immune system
2
Q
What is the dual nature of adaptive immunity
A
It consists of a humoral immunity and cell-mediated immunity
3
Q
When does the body produce antibodies
A
When a substance is recognized as non self or alien
4
Q
What causes production of antibodies
A
antigens
5
Q
What happens after combination of an antibody with a particular antigen occurs
A
- Agglutination
2. Lysis (complement)
6
Q
Humoral immunity
A
Immunity brought about by antibodies
7
Q
B cells
A
- Lymphocyte
- Mature in bone marrow
- Recognize antigens and make specific antibodies against them
- Their recognition depends on their receptors located or coating the surface of the B-cell
8
Q
T cells
A
- Lymphocyte
- Mature under influence of thymus
- Basis of cellular immunity
- Also called T lymphocytes
9
Q
Where are T cells and B cells primarily found
A
in blood and lymphoid organs
10
Q
What do T cells respond to
A
They respond to antigens by way of receptors on their surface called (TCRs) T cell receptors
11
Q
What can contact with an antigen complimentary to a TCR cause
A
It can cause certain T cells to make and secrete cytokines rather than antibodies
12
Q
Immunogens
A
Antigens that cause a highly specific response, resulting in the production of antibodies that are capable of recognizing the antigen (humoral immunity)
13
Q
What components make up an antigen
A
Proteins or large saccharides
14
Q
What are antigenic components
A
Components of invading microbes such as capsules, cell walls, flagella, fimbriae, bacterial toxins, coats of viruses
15
Q
What are the specific regions on antigens that antibodies interact with
A
Epitopes or antigenic determinants
16
Q
Haptens
A
- Low molecular weight compounds
- Too small to provoke immune response
- Often not antigenic unless it is attached to a carrier molecule (Hapten-carrier conjugate)
17
Q
What are the recognizable antigens on pathogenic bacteria called
A
Pathogenic Associated Molecular Patterns
18
Q
What is a well known receptor that recognizes PAMPs
A
Toll-like receptor (TLRs)
19
Q
Antibodies
A
Globulin proteins or immunoglobulins made in response to an antigen, can recognize it and bind to it
20
Q
How many antigen-binding sites does an antibody have
A
At least 2 sites that bind to epitopes
21
Q
Valence
A
The number of antigen-binding sites on an antibody
22
Q
Bivalent
A
antibodies that have 2 binding sites
23
Q
Monomer
A
The simplest molecular structure such as a bivalent antibody
24
Q
What is the structure of a typical antibody monomer
A
- Four protein chains forming a Y shape: 2 identical light chains and 2 identical heavy chains, joined by disulfide links
- (V) Variable regions are the 2 sections at end of Y’s arms
- (Fc) Constant region is the stem, which is identical for a particular Ig class
25
What part of the antibody do epitopes bind to
Variable regions
26
Name the different Ig classes
IgG, IgM, IgA, IgD, IgE
27
IgG Antibodies
1. Monomer
2. 80% of all antibodies in serum
3. In blood, lymph, and intestines
4. Cross placenta: passive immunity
5. Protect against bacteria, viruses, enhance effectiveness of phagocytes, neutralize bacterial toxins, trigger complement system
6. Half life 23 days
28
IgM Antibodies
1. Pentamer, 10 binding sites
2. 5-10% of all serum antibodies i
3. Remain in blood vessels without entering surrounding tissues: blood, lymph, on B cells
4. Agglutinates microbes
5. Responds to ABO type antigens
6. First in response to a primary infection
7. Half-life 5 days
29
What does the detection of IgG antibodies against a pathogen mean
Immunity was acquired in the more distant past
30
What does the detection of IgM antibodies against a pathogen mean
A high concentration would indicate that the pathogen observed is causing the infection
31
IgA Antibodies
1. Dimer
2. 10-15% of serum antibodies
3. In secretions; mucus, saliva, tears, breast milk: colostrum
4. Mucosal protection: prevents attachment of microbial pathogens
5. Half-life 6 days
32
IgD Antibodies
1. Monomer
2. 0.2% of serum antibodies
3. In blood, lymph, and on B cells: initiate immune response
4. Half-life 3 days
33
IgE Antibodies
1. Monomer
2. 0.002% of serum antibodies
3. On mast cells, basophils, in blood
4. Allergic reactions, releases histamines and other chemical mediators
5. Attracts complement and phagocytic cells; lysis of parasitic worms
6. Half-life 2 days
34
What is the humoral response
It is an antibody-mediated response
35
What group of cells produce antibodies
Lymphocytes called B cells
36
What starts the production of antibodies
When B cells are exposed to free or extracellular, antigens
37
What does each B cell carry on their surface
Immunoglobulins that bind to antigens
38
When does the B cell become activated
When a B cells immunoglobulin binds to the epitope for which they are specific
39
What does an activated B cell undergo
Clonal expansion or proliferation
40
Which cell assistance is usually required by B cells to undergo clonal expansion
T helper cells
41
An antigen that requires a T helper cell for antibody production is called
T-dependent antigen
42
T helper cell
contacts the displayed antigen fragment (MCH II) and releases cytokines that activate B cells
43
What are T-dependent antigens
Mainly proteins , such as those found on viruses, bacteria, foreign RBCs, haptens with carrier molecules
44
Major histocompatibility complex (MHC)
genes that encode molecules on the cell surface
45
Class I MHC
A collection of genes that encode molecules of genetically diverse glycoproteins that are found on the plasma membranes of mammalian nucleated cells
46
What type of cells do class MHC I identify
self vs non self; this class identifies the host and prevents immune system from making antibodies that would be harmful to the host
47
MCH class II
Are found on the surface of antigen-presenting cells such as B cells
48
Steps involved in activation of B cells to produce Antibodies
1. APC receptors on B cell recognize and attach to antigens
2. Antigen is internalized and processed, within the B cell a fragment of the antigen combines with MCH II
3. MHC II antigen-fragment complex is displayed on B cell surface
4. The helper T cell recognizes this and secretes cytokines, activating B cell
5. B cell is activated and begins clonal expansion, producing antibody-producing plasma cells and memory cells
49
What are memory cells responsible for
they are long lived and are responsible for the enhanced secondary response to a specific antigen
50
What is clonal selection
The differentiation of B cells into memory and plasma cells
51
Clonal deletion
The elimination by apoptosis of harmful B cells that have receptors for self antigens, occurs at immature lymphocyte stage in bone marrow and thymus
52
T-independent antigens
1. Antigens that stimulate B cells directly without the help of T cells
2. Provoke a weak response, usually producing only IgM
3. No memory cells generated
53
What do plasma cells secrete
antibodies into circulation
54
Recognition of self vs nonself
1. Self is normal host and non self are foreign substances
2. The clonal selection hypothesis and clonal deletion hypothesis
3. This mechanism removes lymphocytes that can destroy host tissues and thereby creates tolerance for self
55
Immunology
the study of immunity and how the immune system responds to specific infectious agents and toxins
56
What type of antigens do children under the age of 2 normally have
T-independent antigens
57
What develops when an encounter between an antibody and its specific antigen occurs
antigen-antibody complex
58
What results from antigen-antibody binding
1. Agglutination
2. opsonization
3. neutralization
4. Antibody-dependent cell mediated cytotoxicity
5. Activation of complement
59
Agglutination
the aggregation and clumping together of cells for easier digestion by phagocytes
60
Opsonization
coating antigen with antibody enhances phagocytosis
61
Antibody-dependent cell mediated cytotoxicity
Antibodies attach to target cell and cause destruction by macrophages, eosinophils, and NK cells
62
Neutralization
Blocks adhesion of bacteria and viruses to mucosa, blocks attachment of toxin
63
Activation of complement system
Triggered by either IgG or IgM, causes inflammation and cell lysis
64
Antibody titer
is the amount of Antibody in serum, reflects intensity of antibody-mediated humoral response
65
Primary response
occurs after initial contact with antigen, first is IgG
66
Secondary response
(memory or anamnestic) Occurs after second exposure, when antigen recognized by memory cells enters the blood
67
What are the 2 mechanisms that can occur as a result of a primary response
1. B cells activate by binding antigen, proliferation, and forming plasma cells, no memory cells (T-indep ant)
2. B cells become APCs and memory cells are formed (T-dep ant)
68
T cells
1. Has specificity for a particular antigen
2. Have (TCRs) T-cell receptors instead of Ig
3. Develop from stem cells in red bone marrow
4. Mature in thymus
5. Located in blood, lymphatic system and tissues
69
Thymic selection
1. Elimination of an immature T cells that do not recognize self molecules
2. Happens in thymus
3. Prevents body from attacking own tissues
70
Gateway cells? Where are they located?
1. microfold cells (M cells)
| 2. Peyer's patches and under epithelial-cell layer in intestinal wall
71
Function of microfold cells
A secondary lymphoid organ that has adapted to take up antigens from intestinal tract and allow transfer to lymphocytes and APCs of immune system
72
What is the most abundant kind of antibodies that are formed in the Peyer's patches
IgA, essential for mucosal immunity
73
What kind of immune cells are located on Peyer's patch
Dendritic cells and macrophages
74
In what other tract are M cells seen
respiratory tract
75
Antigenic-Presenting Cells
cells that digest antigens and break them down into small peptides, and present these antigenic fragments on their surface with a molecule of MHC
76
What cells are considered APCs
B cells, Dendritic cells, Activated macrophages
77
A T cytotoxic cell can differentiate into..
an effector cell called a cytotoxic T lymphocyte
78
T cells are classified by certain glycoproteins on surface, what is this called?
Clusters of differentiation (CD)
79
What are CDs used for
these membrane molecules are important for adhesion to receptors
80
What are the CDs of greatest interest and what cells carry them
1. CD4 and CD8
| 2. CD4+, CD8+
81
How are Helper T cells classified and what do they bind to
1. CD4
| 2. Bind to MHC class II, on B cells and APCs
82
How are T cytotoxic Cells classified and what do they bind to
1. CD8
| 2. MHC class I
83
What is the initial signal for CD4+ T cell activation
its T-cell receptor recognizes an antigen and MHC II on APC
84
What is the secondary signal for CD4+ T cell
Toll like receptors are a costimulatory signal, present on the APC and the T helper cell
85
Activation of T helper cell causes
1. Differentiation into subsets: TH1, TH2, TH17, and long lived memory cells
2. cytokines
86
What do TH 1 produce
IFN-y, which activates cells related to cell-mediated immunity, macrophages, and antibodies--> *phagocytosis, * complement
87
What do TH 2 produce
activate eosinophils and B cells to produce antibodies, especially IgE
88
What do TH 17 produce
large quantities of cytokine IL-17, situated in skin and lining of GI tract, stimulate innate system
89
CD8 or T cytotoxic cells are activated into
CTLs; cytotoxic T lymphocytes
90
The target cells of CTLs are
self-cells that have been altered by infection, carrying fragments of endogenous antigens in combination with MHC I
91
What do target cells carrying endogenous antigens normally include
viral, parasitic, tumor cells, transplanted foreign tissue
92
Can CTLs attack any cell
only MHC , class I, these are nucleated cells, so any host cell that has been altered
93
What CTL release after it attaches to target cell
1. pore-forming protein--> similar action to complement membrane attack complex
2. perforin
3. Granzymes: proteases that induce apoptosis (programmed cell death)
94
Apoptosis
genomes are cut into fragments, external membranes bulge outward (blebbing), signal on surface attract phagocytes
95
Cells associated with cellular immunity
T cells, Dendritic cells, macrophages
96
T regulatory cells
1. T reg cells, CD4 and CD25 on surface
2. Suppress T cells against self immunity
3. form memory cells on skin and around hair follicles, maintain microbiome, protects baby in womb
97
NK cells
1. Granular leukocytes that destroy cells that do not express MHC I or express it in small amounts
2. Kill viruses-infected host cells and tumor cells
3. Attack parasites
98
Cytokines
chemical messengers produced in response to a stimulus
99
Overproduction of cytokines causes
cytokine storm
100
Interleukin-1
(IL-1) stimulates Helper T cells in presence of antigens, attracts phagocytes
101
Interleukin-2
(IL-2) proliferation of antigen-stimulated CD4+ T helper cells, proliferation and differentiation of B cells; activation of CD8+ T cells and NK cells
102
Interleukin-12
(IL-12) inhibits humoral immunity; activates
| TH 1 cellular immunity
103
Natural Immunity
acquired adaptive immunity most often obtained by having a specific disease, through exposure
104
Artificial immunity
acquired adaptive immunity obtained by receiving an antigen by injection of vaccine or immune serum, immune response without disease
105
Active immunity
1. Natural exposure to infectious agent; infection
| 2. Artificial immunization; injections Ag (immunization)
106
Passive immunity
Ready made antibodies
1. Natural maternal antibodies; transplacental, colostrum
2. Artificial antibodies from other sources; injection antibodies (immunoglobulins)
107
Vaccine
a substance that contains an antigen to which the immune system responds
108
toxoid
an inactivated toxin that is no longer harmful, but retains its antigenic properties
109
recommend vaccinations
1. DTap, toxoid-d/taxoid-t/acellular-p
2. Polio vaccine
3. MMR, live virus
110
Cellular immunity
1. produces T lymphocytes
| 2. T cell receptors
111
T lymphocytes
recognize antigenic peptides processed by phagocytic cell
112
TCRs
on T cell surface contact antigens, causing the T cells to secrete cytokines instead of antibodies
113
ILs
cytokines between leukocytes
114
Chemokines
induce migration of WBCs--. inflammation, phagocytes
115
Interferons
interfere with viral infections of host cells
116
TNF-a
tumor necrosis factor alpha; involved in the inflammation of autoimmune diseases
117
Hematopoietic cytokines
control stem cells that develop into red and white blood cells
118
BCR
B cell receptor: a type of antibody that can attach to harmful organism to destroy it
