Immunology 1: cells of the immune system (humoral & cellular immunity) Flashcards
1
Q
cells, tissues, and molecules that mediate resistance to infections.
A
Immune system
2
Q
Study of structure and function of the immune system
A
Immunology
3
Q
Study of out protection from foreign macromolecule or invading organisms and our response to them
A
Immunology
4
Q
Foreign macromolecule (virus protein, worms, parasite) (everything that should not be in the body)
A
Antigen
5
Q
Resistance of a host (human) to pathogens and their toxic effects
A
Immunity.
6
Q
Collective and coordinated response to the introduction of foreign substances in an individual mediated by the cells and molecules of the immune system.
A
Immune response.
7
Q
The immune system is a collection of what?
A
1- organs.
2- cells.
3- molecules (soluble factors).
8
Q
Where do leukocytes develop?
A
Primary (central) lymphoid organs.
9
Q
List primary (central) lymphoid organs?
A
1- bone marrow.
2- thymus.
10
Q
Where does the immune response occur?
A
Secondary (peripheral) lymphoid organs.
11
Q
List secondary (peripheral) lymphoid organs?
A
1- lymph nodes.
2- spleen.
12
Q
Where is the bone marrow located?
A
Middle of bones (vertebrae, pelvic, and leg bones).
13
Q
What does bone marrow generate?
A
T cells, B cells, and macrophages.
14
Q
Where is the thymus located?
A
In the front of the upper chest.
15
Q
What is the thymus function?
A
Acts like a nursery for the development of T cells.
16
Q
Where are lymph nodes located?
A
Throughout the body.
17
Q
What is the lymph nodes function?
A
Filters lymph fluid, removing antigens that get trapped in their web like structure where macrophages, antibodies, and T cells can destroy them.
18
Q
Where is the spleen located?
A
In the upper left side of the abdomen.
19
Q
List the 4 functions of the spleen?
A
1- filters out foreign organisms that infect blood.
2- removing old or damaged platelets and RBCs.
3- storing extra blood and releasing it as needed.
4- helping form some types of WBCs.
20
Q
What can be done to the spleen if it’s damaged?
A
It can be removed but that lowers resistance to infection.
21
Q
List other lymphoid organs?
A
1- tonsils and adenoids.
2- payer’s patches.
3- appendix.
4- lymphatic vessels.
22
Q
List the 3 types of accumulation of lymphoid tissues?
A
1- MALT (mucosa associated lymphoid tissue).
2- GALT (gut associated lymphoid tissue).
3- BALT (bronchus associated lymphoid tissue).
23
Q
How are lymphatic organs interconnected?
A
By the blood and lymphatic vessels through which lymphocytes circulate.
24
Q
All immune cells arise from which stem cell?
A
Hematopoietic stem cell.
25
List the 3 types of bone marrow progenitor?
1- common lymphoid progenitor.
2- myeloid progenitor.
3- erythroid progenitor.
26
Common lymphoid progenitor is precursor of which immune cells?
B cells, T cells and NK cells.
27
B cells are precursors of which cells?
Plasma cell.
28
T cells are a precursor of which cells?
Effector T cells.
29
Myeloid progenitor is a precursor of which immune cells?
Polymorphonuclear leukocytes (neutrophils, eosinophil, basophil).
30
Which immune cells come from an unknown precursor?
1- mast cells.
2- dendritic cells.
31
Monocytes are a precursor of which immune cells?
Macrophages.
32
List WBCs?
1- dendritic cells.
2- monocytes (macrophages).
3- eosinophil.
4- lymphocytes (B lymphocytes, T lymphocytes, NK cells).
5- neutrophils.
6- basophils.
33
What is the percentage of monocytes and macrophages in blood?
5-8%
34
_________ circulate in the blood, ________ in the tissues.
Monocytes, macrophages.
35
Monocytes and macrophages are an important link between what?
Innate and acquired immune responses.
36
Which changes occur during the change of monocytes to macrophages?
1- cell enlarge (5-10x).
2- intracellular organells increase in size and complexity.
3- cells acquire increased phagocytic ability.
4- increased secretion of many soluble factors.
37
Macrophages are dispersed throughout the body some becoming ________ macrophages, whereas others remain _______ and are called _____ or __________ macrophages.
Fixed,
Motile,
Free,
Wandering.
38
Macrophages play which important roles?
1- phagocytosis.
2- opsonization.
3- ADCC (Antibody-dependent cellular cytotoxicity).
4- APCs (Antigen presenting cells).
5- secretion of cytokines (called monokines).
6- synthesis of complement components.
39
List monokines that get secreted by macrophages?
1- IL-1.
2- IL-6.
3- IL-8.
4- IL-12.
5- IL-15.
6- IFN.
7- TNF.
8- prostaglandins.
40
Macrophages are activated by a variety of stimuli, list the?
1- activating comes from chemokines.
2- phagocytosis itself is an important activating stimulus.
3- cytokines secreted by T helper cells (IFN - gamma).
4- mediators of the inflammatory response.
5- microbial products (such as LPS).
41
Where do dendritic cells originate from?
The bone marrow.
42
What makes dendritic cells very efficient at contact with foreign material?
They have dendriform (star shaped).
43
What do dendritic cells function as?
APC (capture antigen or bring it to the lymphoid organs where an immune response is initiated).
44
What do dendritic cells express?
Class I and II MHC (major histocompatibility complex) molecules.
45
Where are dendritic cells present?
Blood, LNs and epithelial cells.
46
Give an example of dendritic cells?
Langerhan cells (skin).
47
List types of tissue macrophages and where are they?
1- alveolar macrophage (lung).
2- osteoclast (bone).
3- histiocyte (CT).
4- kupffer cell (liver).
5- microglia (brain).
6- intestinal macrophage (intestine).
48
Where are mast cells released from?
Bone marrow as undifferentiated and differentiate in the tissues (skin, CT, mucosal epithelium, etc).
49
Mast cell’s morphology and function similar to ________
Basophils.
50
Which receptors do mast cells have?
Have Fc receptors for IgE (FceRs).
51
Mast cells play a very important role in what response?
Allergic response.
52
What do mast cells produce?
A variety of cytokines.
53
What are polymorphonuclear leukocytes (PMNs)?
Granulocytes.
54
List the 3 types of granulocytes?
1- neutrophils.
2- eosinophils.
3- basophils.
55
What are PMNs important for?
Removal of bacteria and parasites from the body, they engulf these foreign bodies and degrade them using their powerful enzymes.
56
What is the percentage of neutrophils in the blood?
50-70% of circulating WBC.
57
A higher number of neutrophils are suggestive of what?
Bacterial infection.
58
Which WBC have multi-lobed nucleus with poorly stained fine granules?
Neutrophils.
59
What enzymes do neutrophils contain?
Bactericidal enzymes.
60
List the bactericidal enzymes found in neutrophils?
Lysozome, NADPH oxidase, lactoferrin and B-12 binding protein, defensins, elastase and myeloperoxidase.
61
Which WBCs are efficient phagocytes?
Neutrophils.
62
Neutrophils don’t function as what?
APCs.
63
Which type of receptors do neutrophils have?
Receptor for Fc region of IgG and C3b.
64
Which WBC are the first to arrive?
Neutrophils.
65
Which WBCs are the most important cells of the innate immune system?
Neutrophils.
66
Which is the percentage of eosinophils in the blood?
1-3% of circulating WBCs.
67
Which WBCs are bi-lobes nucleus and a heavily granulated cytoplasm?
Eosinophils.
68
Eosinophils don’t act as what?
APCs.
69
Which type of receptors do eosinophils have?
Receptors for complement.
70
What is the major role of the eosinophil?
Is believed to be against parasite.
71
How are eosinophils effective against parasites?
Bind to IgE on surface of a worm, the contents of the granules (hydrolytic enzymes) cause damage to the worm’s tegument.
72
What eosinophil protein is highly toxic to worms?
Major basic protein (MBP).
73
Eosinophils are classically seen with which conditions?
1- atopic allergies.
2- worm infections.
3- collagen vascular diseases.
4- neoplastic disorders.
5- skin rash.
74
What is the percentage of circulating basophils?
<1% of circulating WBC.
75
Basophils are only present where?
Bloodstream
76
Which WBC is a lobed nucleus- more variable, large coarse granules?
Basophils.
77
Basophils play a major role in what? And how?
Allergic response, they release histamine, serotonin, heparin, prostaglandin….. etc into the bloodstream.
78
Which receptors do basophils have?
Fc receptors for IgE (FceRs).
79
How do basophils act when an individual is exposed to an allergen? What happens upon re-exposure?
When an individual is exposed to an allergen, allergen specific IgE is produced, this IgE binds to the surface of basophils.
Upon re-exposure to the allergen, the allergen binds to IgE on the surface of basophils resulting in degranulation [effector phase].
80
Which WBCs are agranulocytes?
Lymphocytes.
81
Lymphocytes are responsible for what?
Specific immune response.
82
What is the percentage of circulating lymphocytes?
20-40%
83
Which lymphocytes return 99% of cells in lymph by extravasating and entering the tissues?
Lymphocytes
84
T and B lymphocytes are _____, ______, ___________ cells which ________ be distinguished from each other morphologically.
Small, motile, non-phagocytic cells which cannot be distinguished.
85
Which WBCs are small, 6um, contain a single nucleus, little visible cytoplasm around their nucleus?
Lymphocytes.
86
Once lymphocytes are stimulated with antigen they enlarge _____ into a ________ cell (called _________).
Enlarge 15um into a blast cell, lymphoblasts.
87
What happens to lymphoblasts?
They further differentiate into effector cells or memory cells. (Plasma cells, T-helper cells, T-cytotoxic cells).
88
Different maturational stages of lymphocytes can be distinguished by what?
By their expression of membrane CD molecules (CD= cluster of differentiation).
89
Which CD markers are present on monocytes?
CD45+, CD14+
90
Which CD markers are present on granulocyte?
CD45+, CD15+
91
Which CD markers are present on T lymphocytes?
CD45+, CD3+
92
Which CD markers are present on T helper lymphocytes?
CD45+, CD3+,CD4+
93
Which CD markers are present on T cytotoxic lymphocytes?
CD45+, CD3+, CD8+
94
Which CD markers are present on B lymphocytes?
CD45+, CD19+
95
Which CD markers are present on natural killer cells?
CD45+, CD16+, CD56+, CD3-
96
How long is the life span of effector cells?
Short lived - 2 weeks.
97
How long is the life span of immunological memory?
Long lived - 3yrs or more for life.
98
They are molecules by which we can identify T cells and divide them to subsets
T cell surface markers
99
What are T cell surface markers required for?
Interactions between T cells and APC and for antigen recognition.
100
What T cells receptors are present on activated T cells?
CD3
CD4 or CD8
CD2
CD28
And CD40L
101
A kind of membrane on T cells that can specially bind to the antigenic peptide-MHC molecule complex
T cell receptor.
102
List types of TCR?
1-Alpha beta TCR.
2- Gamma delta TCR.
103
What is the structure of TCR?
1- extracellular region.
2- transmembrane region.
3- cytoplasmic region.
104
What is the structure of extracellular region of TCR?
V region: V alpha and V beta antigen binding site.
CDR1, CDR2, CDR3.
C region: C alpha and C beta.
105
What is the structure of transmembrane region of TCR?
Positive charge.
106
What is the structure of cytoplasmic region of TCR?
Can’t transduce signal (3~12aa).
107
What does CDR stand for?
Complementing determining regions.
108
What is the co receptor of CD4 and CD8?
CD4: class II MHC.
CD8: class I MHC.
109
CD4 and CD8 can also participate in _________ after TCR bind __________ specifically.
Signal transduction,
Antigen
110
CD28 on resting or activated T cells binds to what on APC?
B7 (CD80/CD86).
111
T cells can be turned on by stimulating which receptor?
CD28 receptor
112
Which co-stimulatory receptor transmit a stimulatory signal to T cells?
CD28.
113
What does CTLA-4 stand for?
Cytotoxic T Lymphocyte Antigen-4, CD152.
114
What does CTLA-4 on activated T cells bind to?
B7.
115
What co-stimulatory receptor sends an inhibitory signal to T cells and can turn it off?
CTLA-4.
116
What is a CD2?
Co-stimulatory receptor, LFA-2, sheep red blood cell receptor.
117
Where is CD2 expressed?
On 90% mature T cells (none on B cells).
118
What is the ligand of CD2? And where is it expressed?
CD58 (LFA3), expressed on APC, RBC of human or sheep.
119
List the functions of CD2?
1- formation of E-rosette.
2- Enhancing the binding of TCR and antigen peptide-MHC molecule complex.
3- participate in signal transduction of T cell activation.
120
Where is CD40L present?
On activated TH cells.
121
What is CD40L involved in?
Activation of B cells.
122
What does CD40L bind to?
CD40 molecules on APCs.
123
TH17 cells are another ________ __ _____ ______?
Effector T cell subset.
124
What induces TH17 cells?
Induced from naive CD4+ or CD8+ T cells.
125
What inhibits TH17 cells?
Inhibited by IL-2, IL-4 and IFN- gamma.
126
What do TH17 cells produce?
IL-17 and IL-22.
127
What does IL-17 induce?
Induces expression of G-CSF and chemokines for inflammation with neutrophils.
128
What does IL-22 induce?
Induces anti-bacterial proteins.
129
What are TH17 cells important for?
- Anti-bacterial and anti-fungal infections;
- Chronic autoimmune inflammation in skin, joints and CNS.
130
Class of bacterial toxins (staphylococcal enterotoxins) & retroviral proteins that can activate very large numbers of T cells irrespective of their antigenic specificities?
Super antigens.
131
List the 3 features of super Ags?
1- not processed.
2- interact with the MHC class 2 molecule outside of the peptide - binding groove.
3- bind only to the VB segment of TCR.
132
What are BCRs?
Membrane immunoglobulin’s (mIgM and mIgD).
133
What do BCRs consist of? (Shape)
Consists of 2 identical heavy chains and 2 identical light chains, linked by several disulfide bridges.
134
What is the function of BCRs?
Recognize and bind to specific, intact antigens.
135
List B-cell co-receptors complexes?
1- CD21 (CR2).
2- CD19.
136
List function of CD21 (CR2)?
Enhancing the binding of BCR and antigen and pass activating signal to CD19.
EB virus receptor.
137
List the function of CD19?
Transmit activating signal into B cell.
138
List B-cell co-stimulatory receptor?
1-CD40.
2- B7.
3- MHC molecules.
4- Mitogen receptor.
5- Cytokine receptor.
139
What does the CD40 on B cells bind to?
CD40L on activated T cell.
140
List the functions of CD40?
1- transmit an important co-stimulatory signal to B cells.
2- up-regulate expression of B7 on B cells.
3- participate in class switching of antibody.
141
Where is B7 expressed on?
B cells or other APC.
142
What is stimulatory B7? and what is the inhibitory B7?
- B7-CD28 (stimulatory).
- B7-CTLA-4 (inhibitory) (cytotoxic T lymphocyte antigen-4).
143
List MHC molecules?
Class 1,2, MHC molecules.
144
List mitogen receptors?
LPS.
145
List cytokine receptors?
IL-4R, IL-5R, IL-6R.
146
B-cell subpopulation is listed based on what?
According to expression of CD5 or not.
1- B1 cell (CD5+).
2- B2 cell (CD5-).
147
List the different properties of B1 and B2, based on development, BCR, CD5, reproduction, Ab type, Ab avidity, function?
Development: B1 (early), B2 (late).
BCR: B1 (mIgM), B2 (mIgM and mIgD).
CD5: B1 (+), B2 (-).
Reproduction: B1 (self-renewing), B2 (from pre-B cell in BM).
Ab type: B1 (IgM > IgG), B2 (IgG > IgM).
Ab avidity: B1 (low), B2 (high).
Function: B1 (innate immunity), B2 (adaptive immunity).
148
List the functions of B cell?
1- produce the antibody ——— HI (humoral immunity).
2- present antigen ——— APC.
3- participate in immunological regulation.
149
The measure of the total binding strength of an antibody at every binding site is termed what?
Avidity.
150
Avidity is also known as what?
Functional affinity.
151
Humoral immunity is the immunity to infection through the release of what?
Antibodies (immunoglobulins).
152
What are antibodies and where are they produced from?
1- gamma globulins (proteins) called immunoglobulins (Ig).
2- produced by plasma cells (B-cells firstly turn into plasma cells).
153
Abs constitute which % of total serum proteins?
20-25%
154
Where are Abs located?
In the blood, extravascular tissues, secretions and excretions.
155
What do Abs bind to and where?
Bind pathogenic microorganism and their toxins in extracellular compartments.
156
List the 2 forms of Abs?
1- membrane bound Abs.
2- secreted Abs.
157
____ lymphocytes use ______ _____ Abs to interact with ___.
B lymphocytes,
Membrane bound Abs,
Interact with Ags.
158
What is the structure of Abs?
Y- shaped chains: 2 (L) light, 2 heavy (H).
L chain is smaller and low molecular wt.
H chain is larger and high molecular wt.
159
L chain of Abs is attached to H chain by which bond?
Disulphide and non - covalent bonds.
160
What are the 2 forms of L chain of Abs?
1- kappa (k)
2- lambda.
161
Ig has which L chain form?
Either k or lambda, never both.
162
What are the 2 regions of L and H chains of Abs?
1- Constant (Cl) (Ch) at C - terminal.
2- Variable (Vl) (Ch) at N - terminal.
163
List the H chain for each Ig class?
1- IgM - mu (u).
2- IgA - alpha.
3- IgG- gamma (y)
4- IgE - Eplison (E)
5- IgD- delta.
164
List the subclasses of the Ch region on an Ab?
1- Ch1.
2- Ch2.
3- Ch3.
165
Regions on Abs are also called what?
Domains.
166
What is the shape of the domains in Abs? And what bond stabilizes them?
Globular in shape.
Stabilized by intrachain disulphide bonds.
167
Where are Ags binding site located on an Ab?
In the variable domains.
168
Where is the hinge region located?
Segment of H chain between Ch1 and Ch2.
169
Hinge region is flexible to what?
Ab.
170
Hinge region is susceptible to what?
Enzymes and chemicals (e.g. pepsin and papain).
171
List the 2 fragments of immunoglobulins?
1-Fab.
2-Fc.
172
Fc fragment of Ab is composed of what?
Carboxy terminal of H chain.
173
Fc fragment of Ab determines what?
Determines the biological properties of Ig molecule.
174
Receptors for Fc portion is expressed by what?
1- mononuclear cells.
2- neutrophils.
3- NK cells.
4- eosinophils.
5- mast cells.
175
Amino acid sequence in the _____ of L and H are not _______ ________.
Variable region,
Not uniformly variable.
176
What does the hypervariable regions consist of?
Some highly variable (hypervariable) and some relatively invariable zones.
177
Highly variable zones actually make contact with the epitope on an Ag and are called what?
Complementarity determining regions (CDRs).
178
_________ is the longest and most variable of the three CDRs
CDR3.
179
5 classes of Igs are based on what?
Constant region of heavy chains.
180
______ subtypes of IgG and __ of IgA.
4 (IgG1-4),
2 (IgA1, IgA2).
181
Which Ig has the highest number of antigen - binding sites
IgM (10)
182
Which Ig has the heaviest molecular weight?
IgM (900,000 daltons).
183
Which Ig has the lowest molecular weight?
IgG (500,000 daltons).
184
Which Ig has the highest percentage of total antibody in the serum?
IgG (80%) (major).
185
Which Igs have the lowest percentage of total antibody in the serum?
IgD and IgE (>1%).
186
Which Ig can cross the placenta?
IgG.
187
Which Igs fix complements?
IgG and IgM
188
Fc of IgG binds to what?
Phagocytes.
189
Fc of IgE binds to what?
Mast cells and basophils.
190
What is the function of IgG?
Neutralization,
Agglutination,
Complement activation,
Opsonization,
And antibody-dependent cell-mediated cytotoxicity.
191
What Ig is the major Ab of secondary response?
IgG.
192
What is the function of IgM?
Neutralization,
Agglutination,
And complement activation.
The monomer form serves as the B cell receptor.
193
Which Ig is 1st immune response?
IgM.
194
What is the function of secretory IgA?
Neutralization and trapping of pathogens in mucus.
195
What is the function of IgD?
B-cell receptor.
196
What is the function of IgE?
Activation of basophils and mast cells against parasites and allergens.
197
Which immune cells are large granular lymphocytes?
NK cells.
198
Which immune cells is CD3 -ve, CD16 +ve and CD56 +ve?
NK cells.
199
List the 4 functions of NK cells?
1- mainly in innate immunity.
2- kill tumor cells.
3- kill virus/bacteria infected cells (intracellular pathogens).
4- graft cells.
200
How do NK cels recognize foreign Ags?
Independent of MHC.
201
How are NK cells activated?
By cytokines (IL-2, IL-12, IL-15, IFN-alpha, IFN- beta).
202
What do NK cells secret?
IFN- gamma.
203
NK cells activated by IL-2 are also called what?
Lymphokine activated killer (LAK).
204
What is LAK used in?
Cancer immunotherapy.
205
How do NK cells differ from CTLs?
1- non-specific.
2- act spontaneously (no recognition nor activation).
3- not MHC restricted.
4- it is ADCC.
206
List the 3 mechanisms of NK cells?
1- have granules that contain perforins which create pores in target cell membrane.
2- have granzymes that enter through pores and induce apoptosis of target cells.
3- mediate Ab-dependent cellular toxicity (ADCC), kill opsonized or Ab-coated cells (it has Fc receptors, CD16, for IgG).
207
Why do NK cells not kill normal cells?
Activation and recognition of target cells is regulated by a combination of
1- killer activating receptors (KARs) and,
2- killer inhibitory receptors (KIRs) on NK cells.
Normally, KIRs bind to MHC1 which is present among all normal cells, so they inhibit NK cells action.
Activation of KARs is induced by binding of KARs to stress molecules on infected cells.
208
What are toll-like receptors (TLRs)?
Transmembrane proteins.
209
Where are Toll-like receptors (TLRs) present on?
Macrophages, denderitic cells, epithelial cells.
210
Why are TLRs an important part of innate immune system?
1- they look out for microbes (or their components).
2- they bind to the microbes (or their components).
3- they trigger a cascade of events to kill or protect against pathogens.
211
List the molecules of the immune system?
1- antibodies.
2- complement.
3- cytokines.
4- interleukins.
5- interferons.
