Chap 17 Flashcards
(260 cards)
1
Q
Adaptive immunity
A
defenses that target a specific pathogen
2
Q
adaptive immunity is acquired through
A
infection or vaccination
3
Q
Primary response
A
first time the immune system combats a particular foreign substance
4
Q
Secondary response
A
later interactions with the same foreign substance; faster and more effective due to “memory”
5
Q
Humoral immunity
A
Produces antibodies that combat foreign molecules known as antigens
6
Q
B cells
A
lymphocytes that are created and mature in red bone marrow
7
Q
B cells functions
A
Recognize antigens and make antibodies
8
Q
B cells named for
A
Named for bursa of Fabricius in birds
9
Q
Cellular immunity (cell-mediated immunity) produces
A
T lymphocytes
10
Q
T lymphocytes function
A
Recognize antigenic peptides processed by phagocytic cells
11
Q
T lymphocytes mature in the
A
Thymus
12
Q
T cell receptors (TCRs) located on
A
T cell surface
13
Q
TCRs function
A
contact antigens, causing the T cells to secrete cytokines instead of antibodies
14
Q
Pluripotent stem cells develop in
A
the red bone marrow or fetal liver
15
Q
Stem cell
A
diverges into
two cell lines
16
Q
Thymus
A
Differentiate to
T cells in thymus
17
Q
Migrate to lymphoid
tissue such as spleen,
but especially lymph
nodes
A
both B and T cells
18
Q
Differentiate to
B cells in
A
adult bone marrow
19
Q
Cellular immunity attacks antigens that have already
A
entered cells
20
Q
Cellular immunity attacks antigens that have already entered cells such as
A
some intracellular bacteria such as M. leprae and L. monocytogenes; viruses
21
Q
Humoral immunity fights
A
invaders and threats outside cells
22
Q
Humoral immunity fights invaders and threats outside cells such as
A
1.Extracellular bacteria and toxins
2.Viruses before they enter a host cell
23
Q
Cytokines
A
chemical messengers produced in response to a stimulus
24
Q
Interleukins (ILs)
A
cytokines between leukocytes
25
Chemokines
induce migration of leukocytes
26
Interferons (IFNs)
interfere with viral infections of host cells
27
Tumor necrosis factor alpha (TNF-α)
involved in the inflammation of autoimmune diseases
28
Hematopoietic cytokines
control stem cells that develop into red and white blood cells
29
Overproduction of cytokines leads to a
cytokine storm
30
Antigens
substances that cause the production of antibodies
31
Usually components of invading microbes or foreign substances
Antigens
32
Antibodies interact with
epitopes, or antigenic determinants, on the antigen
33
Haptens
antigens too small to provoke immune responses; attach to carrier molecules
34
Hapten-carrier conjugate
hapten molecules+ carrier molecules
35
Globular proteins called
immunoglobulins (Ig)
36
Valence
is the number of antigen-binding sites on an antibody
37
Bivalent antibodies have two
binding sites
38
Four protein chains form a
Y-shape
39
Two identical light chains and two identical heavy chains joined by
disulfide links
40
Variable (v) regions are at the ends of
the arms; bind epitopes
41
Constant (Fc) region is the
stem, which is identical for a particular Ig class
42
Five classes of Ig
IgG, IgM, IgA, IgD, IgE
43
IgG is a type of
monomer
44
80% of serum antibodies
IgG
45
IgG found in
blood, lymph, and intestine
46
Cross the placenta and protect the fetus; trigger complement; enhance phagocytosis; neutralize toxins and viruses
functions of IgG
47
Functions of IgG
1. Cross the placenta and protect the fetus;
2. trigger complement;
3. enhance phagocytosis;
4. neutralize toxins and viruses
48
Pentamer made of five monomers held with a J chain
IgM
49
6% of serum antibodies
IgM
50
Remain in blood vessels
IgM
51
Cause clumping of cells and viruses
IgM
52
First response to an infection; short-lived
IgM
53
Monomer in serum; dimer in secretions
IgA
54
13% of serum antibodies
IgA
55
Common in mucous membranes, saliva, tears, and breast milk
IgA
56
Prevent microbial attachment to mucous membranes
IgA
57
Monomer
0.02% of serum antibodies
IgD
58
Structure similar to IgG
IgD
59
In blood, in lymph, and on B cells
IgD
60
No well-defined function; assists in the immune response on B cells
IgD
61
Monomer
0.002% of serum antibodies
IgE
62
On mast cells, on basophils, and in blood
IgE
63
Cause the release of histamines when bound to antigen; lysis of parasitic worms
IgE
64
Major histocompatibility complex (MHC) genes encode
molecules on the cell surface
65
Class I MHC are on the membrane of
nucleated animal cells
66
Class I MHC identify
self
67
Class II MHC are on the surface of
antigen-presenting cells (APCs), including B cells
68
Inactive B cells contain surface Ig that
bind to antigen
69
B cell internalizes and
processes antigen
70
Antigen fragments are displayed on
MHC class II molecules
71
T helper cell (TH) contacts
the displayed antigen fragment and releases cytokines that activate B cells
72
B cell undergoes proliferation
clonal expansion
73
Activation of B Cells to Produce Antibodies step 1
APC receptors
recognize and
attach to antigen.
74
Activation of B Cells to Produce Antibodies step 2
Antigen is
phagocytized and
digested
75
Activation of B Cells to Produce Antibodies step 3
Antigen fragments are
displayed on the B cell
surface, attracting a
matching T helper cell.
76
Activation of B Cells to Produce Antibodies step 4
T helper cell
secretes cytokines,
activating a B cell.
77
Activation of B Cells to Produce Antibodies step 5
The activated B cell begins
clonal expansion, producing an
army of antibody-producing
plasma cells and memory cells
(not shown).
78
Clonal Selection and Differentiation of B Cells step 1
Stem cells differentiate into mature B cells,
each bearing surface immunoglobulins
against a specific antigen.
79
Clonal Selection and Differentiation of B Cells step 2
B cell II encounters its specific antigen
and proliferates.
80
Clonal Selection and Differentiation of B Cells step 3
Some B cells proliferate into long-lived
memory cells, which at a later date can be
stimulated to become antibody-
producing plasma cells.
81
Clonal Selection and Differentiation of B Cells step 4
Other B cells proliferate
into antibody-producing
plasma cells.
82
Clonal Selection and Differentiation of B Cells step 5
Plasma cells secrete antibodies
into circulation.
83
T-dependent antigen
Antigen that requires a TH cell to produce antibodies
84
T-independent antigens stimulate
the B cell without the help of T cells
85
T-independent antigens provoke
a weak immune response, usually producing IgM
86
T-independent antigens do not generate which cells?
memory cells
87
T-independent antigen is which type of molecule?
polysaccharide
88
17-10 On what part of the antibody molecule do we find the amino acid sequence that makes the huge genetic diversity of antibody production possible?
variable region
89
An antigen–antibody complex forms when
antibodies bind to antigens
90
affinity
strength of the bond in antigen-antibody complex
91
how does the antigen-antibody complex protect the host?
Protects the host by tagging foreign molecules or cells for destruction
92
What happens after the antigen antibody complex is formed?
1.Agglutination
2.Opsonization
3.Antibody-dependent cell-mediated cytotoxicity
4. Neutralization
5.Activation of the complement system
93
results of agglutination
Reduces number of infectious
units to be dealt with
94
Results of opsonization
Coating antigen with antibody
enhances phagocytosis
95
results of Neutralization
1.Blocks adhesion of bacteria
and viruses to mucosa
2. Blocks attachment
of toxin
96
Results of Antibody-dependent cell-mediated cytotoxicity
Antibodies attached to target cell
cause destruction by macrophages,
eosinophils, and NK cells
97
Results of activation of complement
Causes inflammation and cell lysis
98
T cells combat
intracellular pathogens
99
Thymic selection
eliminates immature T cells
100
T cells migrate from
thymus to lymphoid tissues
101
T cells attach to antigens via
T-cell receptors (TCRs)
102
Pathogens entering the gastrointestinal tract pass through
microfold cells (M cells)
103
M cells located over
Peyer's patches
104
Microfold cells
Cells that take up and transfer antigens to lymphocytes, on Peyer’s patches.
105
Peyer's patches
Lymphoid organs on the intestinal wall
106
Transfer antigens to lymphocytes and antigen-presenting cells (APCs)
Peyer's patches
107
M cells and epithelial cells form specialized
tissue structures called
Peyer’s patches
108
There are closely packed microvilli on the epithelial cells surrounding
Peyer's patches
109
M cells facilitate contact between
antigens passing through the intestinal
tract and cells of the body's immune system.
110
Dendritic cells (DCs)
Engulf and degrade microbes and display them to T cells
111
Dendritic cells found in
skin, genital tract, lymph nodes, spleen, thymus, and blood
112
Macrophages activated by
cytokines or the ingestion of antigenic material
113
Macrophages migrate to
the lymph tissue, presenting antigen to T cells
114
Clusters of differentiation
CD
115
CD4+
T helper cells (TH)
116
What do CD4+ T helper cells do?
Cytokine signaling with B cells; interact directly with antigens
117
CD4+ Bind
MHC class II molecules on B cells and APCs
118
CD8+
Cytoxic T lymphocytes (CTL)
Bind MHC class I molecules
119
TCR on the TH cell recognize and bind to
the antigen fragment and MHC class II on APC
120
APC or TH secretes a
costimulatory molecule, activating the TH cell
121
TH cells produce cytokines and differentiate into
TH1,TH2,TH17, memory cells
122
Activation of CD4+ T Helper Cells step 1
An APC encounters and ingests a microorganism. The antigen is enzymatically processed into short peptides, which combine with MHC class II molecules and are displayed on the surface of
the APC.
123
Activation of CD4+ T Helper Cells step 2
A receptor (TCR) on the surface of the CD4+ T helper cell (TH cell) binds to the MHC–antigen complex. The
TH cell or APC is stimulated to secrete a costimulatory molecule. These two signals activate the TH cell, which produces cytokines.
124
Activation of CD4+ T Helper Cells step 3
The cytokines cause the TH cell (which recognizes a dendritic cell
that is producing costimulatory molecules) to become activated.
125
TH 17 cells produce
IL-17 and contribute to inflammation
126
TH1 cells produce
IFN-y
127
IFN-Y activates
1. Macrophages
2. Complement
3. Antibody production (phag)
macrophages, enhances complement, and stimulates antibody production that promotes phagocytosis
128
TH2 cells release
IL-4 cytokine
129
IL-4 cytokine activates
B cells to produce IgE; activate eosinophils
130
secrete cytokines that
promote inflammatory responses;
recruit neutrophils for protection
against extracellular bacteria
and fungi
TH 17 cells
131
Important in allergic responses,
especially by production of IgE.
Activate eosinophils to control
extracellular parasites such as
helminths (see ADCC discussion).
IL4 TH2 cells
132
cytokines (such as IFN-γ and IL-2) activate CD8+ T cells and NK cells, which control intracellular pathogens by killing infected host cells. They also enhance phagocytosis by antigen-presenting cells such as macrophages.
TH1
133
T regulatory cells
Lymphocytes that appear to suppress other T cells
134
Subset of CD4+ cells; carry an additional CD25 molecule
T regulatory cells
135
functions of T regulatory cells
1.Suppress T cells against self;
2.protect intestinal bacteria required for digestion;
3.protect fetus
136
Precursor T cytotoxic cells (CTLp) are activated to become
cytotoxic T lymphocytes (CTLs)
137
Activated into cytotoxic T lymphocyte (CTL) with the help of
TH cells and costimulatory signals
138
CTLs recognize and
kill self-cells altered by infection
139
Self-cells carry
endogenous antigens
140
endogenous antigens are carried on
surface presented with MHC class I molecules.
141
endogenous antigens
(1) infection caused by an opportunistic pathogen from an individual’s own normal microbiota. (2) Surface antigens on human cells produced as a result of infection.
142
CTL releases ________ and __________ that induce apoptosis in the infected cell
perforin and granzymes
143
releases perforin and granzymes that induce apoptosis in the infected cell
Cytotoxic T Lymphocytes (CD8+ T Cells)
144
A normal cell will not trigger a response
by a cytotoxic T lymphocyte (CTL), but
a
virus-infected cell or a cancer
cell produces abnormal endogenous antigens
145
The abnormal antigen is presented on
the cell surface in association with
MHC
class I molecules.
146
Binding of a TH1 cell
promotes
secretion of cytokines
147
cytokines activate a
precursor CTL (CTLp),
which
produces a clone
of CTLs.
148
CTL induces destruction of
virus-infected cell by apoptosis.
149
What prevents the spread of infectious viruses into other cells?
Apoptosis
150
During apoptosis, cells cut their genome into
fragments, causing the membranes to bulge outward via blebbing
151
Blebbing
bulging of plasma membranes as the cell dies
152
Natural Killer cells kill which cells?
Granular leukocytes destroy cells that don't express MHC class I self-antigens
153
function of NK cells
Kill virus-infected and tumor cells and attack parasites
154
NK cells not always stimulated by
an antigen
155
NK cells form pores in the target cells leading to
lysis or apoptosis
156
Activates cells related to cell-mediated immunity; macrophages, CTLs, and natural killer cells
TH1 (THelper)
157
Stimulates production of eosinophils, IgM and IgE
T Helper TH2 cell
158
Recruits neutrophils; stimulates production of antimicrobial proteins
T helper TH17 cell
159
Destroys target cells on contact by inducing apoptosis
Cytotoxic T Lymphocyte CTL
160
Regulates immune response and helps maintain self-tolerance
T regulatory cell
161
Enhanced phagocytic activity; attacks cancer cells
Activated macrophage
162
Attacks and destroys target cells; participates in antibody-dependent cell-mediated cytotoxcicity
Natural Killer cell (NK)
163
are too large to be phagocytized
Protozoans and helminths
164
Protozoan or helminth target cell is coated with
antibodies
165
Immune system cells attach to which region of antibodies?
Fc regions of antibodies
166
Target cell is lysed by chemicals secreted by
the immune system cell
167
Antibody-Dependent Cell-Mediated Cytotoxicity
The killing of antibody-coated cells by natural killer cells and leukocytes.
168
too large for ingestion by phagocytic cells must be attacked externally
organisms and many parasites
169
Occurs after the second exposure to an antigen
Secondary (memory or anamnestic) response
170
Class switching
where initial IgM response shifts to IgG, IgE, or IgA, occurs
171
More rapid, lasts many days, greater in magnitude
Secondary (memory or anamnestic) response
172
Memory cells produced in response to the initial exposure are activated by the
secondary exposure
173
Antibody titer
relative amount of antibody in the serum
174
Antibody titer reflects
intensity of the humoral response
175
Resulting from infection
Naturally acquired active immunity
176
Transplacental or via colostrum
Naturally acquired passive immunity
177
Injection of vaccination (immunization)
Artificially acquired active immunity
178
Injection of antibodies
Artificially acquired passive immunity
179
The serum fraction containing immunoglobulins (antibodies); also called immune serum globulin.
gamma globulin
180
Gamma globulin
The serum fraction containing immunoglobulins (antibodies); also called immune serum globulin.
181
Control of freely circulating pathogens
humoral adaptive immunity
182
control of intracellular pathogens
Cellular immune system
183
Humoral immunity also called
antibody-mediated immunity
184
Humoral immunity is directed at
Freely circulating pathogens and depends on B cells
185
Cellular immunity, also called cell-mediated immunity, depends on
T cells to eliminate intracellular pathogens, reject foreign tissue, destroy tumor cells
186
The adaptive immune system provides
specificity, clonal expansion, and memory
187
Examples of innate nonspecific defenses
1. first line (skin and mucous membranes)
2. Phagocytosis
3. inflammation
4. complement system
188
Two main divisions of adaptive defense
humoral immunity, cell-mediated immunity
189
Humoral immune response
consists of B cells, and the antibodies they produce
190
cell-mediated immunity
fights intracellular pathogens and cancer cells
191
protagonists of cell-mediated immunity
T lymphocytes
192
types of T lymphocytes
1. Helper T cells
2. Cytotoxic T cells
193
secrete cytokines to activate other cells of the immune system
Helper T cells
194
Attack infected cells directly
cytotoxic T cells
195
the innate and adaptive immune system are interdependent, meaning
they work together to carry out host defenses
196
Humoral immune response
Activity of B cells and the antibodies they produce
197
antigen presenting cells
certain phagocytic cells of the immune system, show what is captured
198
Infected cell needs to show that it was
infected
199
Antigen processing and presentation
is a way for a cell to display information about its activities
200
The process of B cell activation is called
clonal selection
201
What happens during clonal selection?
B cell with a specific antigen receptor recognizes an antigen.
202
The B cell with the specific antigen proliferates to
a clone of cells with the same specificity. a lot of cells with the same specificity
203
The clones of B cells differentiate into
memory B cells and plasma cells
204
clonal expansion
making a lot of cell copies to fight a specific pathogen
205
plasma cells make
antibodies with several functions
206
The antibodies bind to antigens to produce the
humoral response
207
in the simplest form of B cell activation, an antigen called a T-independent antigen
enters the lymphatic tissues and binds to a B cell receptor on the surface of a B cell
208
B cell receptors on a particular B cell are identical and very specific to
just one antigen
209
once the BCR binds to the T-independent antigen, the B cell becomes
activated
210
When the B cell becomes activated, it is ready to
proliferate
211
most antigens are not potent enough to activate B cells themselves, so
the B cell will require a second opinion from a helper T cell to activate
212
T dependent antigens
B cell that needs second opinion from helper T cell to become activated
213
The helper T cell recognizes the antigen as its presented by the B cell and secretes
cytokines to tell the B cell to become activated
214
What happens to the B cell once it becomes activated?
it proliferates making a clone of cells specific to the same antigen
215
some B cells differentiate into
long-lived memory B cells
216
Most B cells differentiate into
plasma cells that secrete antibodies against the antigen that activated them
217
Antibodies can enter the blood stream and travel throughout
the body
218
Plasma cells only live for
a few days
219
Each plasma cell makes approximately how many antibodies per second
2000, enormous quantities of circulating antibodies
220
The antibodies produced by plasma cells have several
functions
221
Since each antibody has at least two antigen binding sites,
antibodies can bind to more than one microbial cell, resulting in agglutination, or clumping
222
helps remove microorganisms from the body
Agglutination
223
neutralize toxins, viruses and bacteria
antibodies
224
How do antibodies neutralize toxins, viruses and bacteria
by binding to critical portions of the toxin, or blocking proteins necessary for attachment to cells.
225
antibodies also act as _______ for phagocytosis
opsonins
226
can activate the complement system
antibodies
227
Have two classes of special proteins used to present antigens on their surfaces
APCs such as macrophages and dendritic cells
228
MHC
proteins used to present antigens on surfaces of APCs
229
Class I MHC proteins
used to present antigens produced within the cell
230
MHC II proteins
used to present antigens engulfed by antigen presenting cells
231
Most of the other cells in the body, including infected cells are also able to
present antigens
232
Most of the other cells in the body, including infected cells are also able to present antigens, however, these cells only have the
Class I MHC proteins
233
Each cytotoxic T cell produces a unique
T cell receptor which corresponds to a specific antigen
234
Each cytotoxic T cell also produces a receptor called
CD8
235
function of CD8
recognizes the MHC molecules of infected cells
236
When a cytotoxic T-cell encounters an infected cell with the specific antigen bound in an MHC molecule
the cytotoxic T cell produces receptors for IL-2 and other cytokines, and IFN-Y
237
The cytotoxic T cell can ten be activated by
cytokines from activated helper T cells
238
What happens when a cytotoxic T-cell becomes activated,
it proliferates, forming a clone of cells specific to the same antigen
239
some of these cytotoxic T cells differentiate into
long lived memory cells
240
Most cytotoxic T cells differentiate into
mature T cells and attack and destroy infected cells
241
cytotoxic T cells can destroy infected cells through multiple
pathways
242
perforin-granzyme cytotoxic pathway
when the cytotoxic T cell encounters an infected cell with the target antigen bound in an MHC molecule, the T cell secreted two types of proteins called perforin and granzyme
243
perforin forms a
pore in the membrane of the target cell, allowing granzyme to enter the cell.
244
granzyme activates
enzymes inside the cell leading to apoptosis
245
the humoral immune response experiences periods of
ramping up and gradual diminishing in response to a foreign invader
246
after the first exposure to an antigen, there is a lag period in which
the exposed person's serum does not contain any detectable antibodies
247
after several days, the concentration of antibodies slowly
rises
248
after slowly rising, there is a gradual ________ of antibodies
decline
249
if memory b cells become stimulated by the original antigen, even years later
They rapidly produce antibody-secreting plasma cells
250
epitopes,
or antigenic determinants, on the antigen
251
Where to find IgA ?
1.mucous membranes,
2.saliva,
3.tears
4. breast milk
252
Where to find IgD ?
In blood, in lymph, and on B cells
253
IgE location
1.mast cells,
2.basophils,
3. blood
254
IgD function
No well-defined function; assists in the immune response on B cells
255
Function of IgM
1. Clumping of cells and viruses
2. First response to infection
3. Remain in blood vessels
256
Function of IgA
Prevent microbial attachment to mucous membranes
257
IgE function
1. Releases histamine
2. lysis of parasitic worms
258
Cytoxic T lymphocytes (CTL)
Bind MHC class ___ molecules
I
259
Why do macrophages migrate to lymph tissue?
To present antigen to T cells
260
What causes endogenous antigens?
1. Opportunistic normal microbes
2. Antigens made by infection
infection caused by an opportunistic pathogen from an individual’s own normal microbiota. (2) Surface antigens on human cells produced as a result of infection.
