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HD > Immunology 1: cells of the immune system (humoral & cellular immunity) > Flashcards

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

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2
Q

Study of structure and function of the immune system

A

Immunology

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3
Q

Study of out protection from foreign macromolecule or invading organisms and our response to them

A

Immunology

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4
Q

Foreign macromolecule (virus protein, worms, parasite) (everything that should not be in the body)

A

Antigen

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5
Q

Resistance of a host (human) to pathogens and their toxic effects

A

Immunity.

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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.

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7
Q

The immune system is a collection of what?

A

1- organs.
2- cells.
3- molecules (soluble factors).

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8
Q

Where do leukocytes develop?

A

Primary (central) lymphoid organs.

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9
Q

List primary (central) lymphoid organs?

A

1- bone marrow.
2- thymus.

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10
Q

Where does the immune response occur?

A

Secondary (peripheral) lymphoid organs.

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11
Q

List secondary (peripheral) lymphoid organs?

A

1- lymph nodes.
2- spleen.

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12
Q

Where is the bone marrow located?

A

Middle of bones (vertebrae, pelvic, and leg bones).

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13
Q

What does bone marrow generate?

A

T cells, B cells, and macrophages.

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14
Q

Where is the thymus located?

A

In the front of the upper chest.

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15
Q

What is the thymus function?

A

Acts like a nursery for the development of T cells.

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16
Q

Where are lymph nodes located?

A

Throughout the body.

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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.

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18
Q

Where is the spleen located?

A

In the upper left side of the abdomen.

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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.

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20
Q

What can be done to the spleen if it’s damaged?

A

It can be removed but that lowers resistance to infection.

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21
Q

List other lymphoid organs?

A

1- tonsils and adenoids.
2- payer’s patches.
3- appendix.
4- lymphatic vessels.

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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).

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23
Q

How are lymphatic organs interconnected?

A

By the blood and lymphatic vessels through which lymphocytes circulate.

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24
Q

All immune cells arise from which stem cell?

A

Hematopoietic stem cell.

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25
Q

List the 3 types of bone marrow progenitor?

A

1- common lymphoid progenitor.
2- myeloid progenitor.
3- erythroid progenitor.

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26
Q

Common lymphoid progenitor is precursor of which immune cells?

A

B cells, T cells and NK cells.

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27
Q

B cells are precursors of which cells?

A

Plasma cell.

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28
Q

T cells are a precursor of which cells?

A

Effector T cells.

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29
Q

Myeloid progenitor is a precursor of which immune cells?

A

Polymorphonuclear leukocytes (neutrophils, eosinophil, basophil).

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30
Q

Which immune cells come from an unknown precursor?

A

1- mast cells.
2- dendritic cells.

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31
Q

Monocytes are a precursor of which immune cells?

A

Macrophages.

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32
Q

List WBCs?

A

1- dendritic cells.
2- monocytes (macrophages).
3- eosinophil.
4- lymphocytes (B lymphocytes, T lymphocytes, NK cells).
5- neutrophils.
6- basophils.

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33
Q

What is the percentage of monocytes and macrophages in blood?

A

5-8%

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34
Q

_________ circulate in the blood, ________ in the tissues.

A

Monocytes, macrophages.

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35
Q

Monocytes and macrophages are an important link between what?

A

Innate and acquired immune responses.

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36
Q

Which changes occur during the change of monocytes to macrophages?

A

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.

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37
Q

Macrophages are dispersed throughout the body some becoming ________ macrophages, whereas others remain _______ and are called _____ or __________ macrophages.

A

Fixed,
Motile,
Free,
Wandering.

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38
Q

Macrophages play which important roles?

A

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.

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39
Q

List monokines that get secreted by macrophages?

A

1- IL-1.
2- IL-6.
3- IL-8.
4- IL-12.
5- IL-15.
6- IFN.
7- TNF.
8- prostaglandins.

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40
Q

Macrophages are activated by a variety of stimuli, list the?

A

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).

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41
Q

Where do dendritic cells originate from?

A

The bone marrow.

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42
Q

What makes dendritic cells very efficient at contact with foreign material?

A

They have dendriform (star shaped).

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43
Q

What do dendritic cells function as?

A

APC (capture antigen or bring it to the lymphoid organs where an immune response is initiated).

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44
Q

What do dendritic cells express?

A

Class I and II MHC (major histocompatibility complex) molecules.

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45
Q

Where are dendritic cells present?

A

Blood, LNs and epithelial cells.

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46
Q

Give an example of dendritic cells?

A

Langerhan cells (skin).

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47
Q

List types of tissue macrophages and where are they?

A

1- alveolar macrophage (lung).
2- osteoclast (bone).
3- histiocyte (CT).
4- kupffer cell (liver).
5- microglia (brain).
6- intestinal macrophage (intestine).

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48
Q

Where are mast cells released from?

A

Bone marrow as undifferentiated and differentiate in the tissues (skin, CT, mucosal epithelium, etc).

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49
Q

Mast cell’s morphology and function similar to ________

A

Basophils.

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50
Q

Which receptors do mast cells have?

A

Have Fc receptors for IgE (FceRs).

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51
Q

Mast cells play a very important role in what response?

A

Allergic response.

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52
Q

What do mast cells produce?

A

A variety of cytokines.

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53
Q

What are polymorphonuclear leukocytes (PMNs)?

A

Granulocytes.

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54
Q

List the 3 types of granulocytes?

A

1- neutrophils.
2- eosinophils.
3- basophils.

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55
Q

What are PMNs important for?

A

Removal of bacteria and parasites from the body, they engulf these foreign bodies and degrade them using their powerful enzymes.

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56
Q

What is the percentage of neutrophils in the blood?

A

50-70% of circulating WBC.

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57
Q

A higher number of neutrophils are suggestive of what?

A

Bacterial infection.

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58
Q

Which WBC have multi-lobed nucleus with poorly stained fine granules?

A

Neutrophils.

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59
Q

What enzymes do neutrophils contain?

A

Bactericidal enzymes.

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60
Q

List the bactericidal enzymes found in neutrophils?

A

Lysozome, NADPH oxidase, lactoferrin and B-12 binding protein, defensins, elastase and myeloperoxidase.

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61
Q

Which WBCs are efficient phagocytes?

A

Neutrophils.

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62
Q

Neutrophils don’t function as what?

A

APCs.

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63
Q

Which type of receptors do neutrophils have?

A

Receptor for Fc region of IgG and C3b.

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64
Q

Which WBC are the first to arrive?

A

Neutrophils.

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65
Q

Which WBCs are the most important cells of the innate immune system?

A

Neutrophils.

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66
Q

Which is the percentage of eosinophils in the blood?

A

1-3% of circulating WBCs.

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67
Q

Which WBCs are bi-lobes nucleus and a heavily granulated cytoplasm?

A

Eosinophils.

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68
Q

Eosinophils don’t act as what?

A

APCs.

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69
Q

Which type of receptors do eosinophils have?

A

Receptors for complement.

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70
Q

What is the major role of the eosinophil?

A

Is believed to be against parasite.

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71
Q

How are eosinophils effective against parasites?

A

Bind to IgE on surface of a worm, the contents of the granules (hydrolytic enzymes) cause damage to the worm’s tegument.

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72
Q

What eosinophil protein is highly toxic to worms?

A

Major basic protein (MBP).

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73
Q

Eosinophils are classically seen with which conditions?

A

1- atopic allergies.
2- worm infections.
3- collagen vascular diseases.
4- neoplastic disorders.
5- skin rash.

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74
Q

What is the percentage of circulating basophils?

A

<1% of circulating WBC.

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75
Q

Basophils are only present where?

A

Bloodstream

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76
Q

Which WBC is a lobed nucleus- more variable, large coarse granules?

A

Basophils.

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77
Q

Basophils play a major role in what? And how?

A

Allergic response, they release histamine, serotonin, heparin, prostaglandin….. etc into the bloodstream.

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78
Q

Which receptors do basophils have?

A

Fc receptors for IgE (FceRs).

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79
Q

How do basophils act when an individual is exposed to an allergen? What happens upon re-exposure?

A

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].

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80
Q

Which WBCs are agranulocytes?

A

Lymphocytes.

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81
Q

Lymphocytes are responsible for what?

A

Specific immune response.

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82
Q

What is the percentage of circulating lymphocytes?

A

20-40%

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83
Q

Which lymphocytes return 99% of cells in lymph by extravasating and entering the tissues?

A

Lymphocytes

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84
Q

T and B lymphocytes are _____, ______, ___________ cells which ________ be distinguished from each other morphologically.

A

Small, motile, non-phagocytic cells which cannot be distinguished.

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85
Q

Which WBCs are small, 6um, contain a single nucleus, little visible cytoplasm around their nucleus?

A

Lymphocytes.

86
Q

Once lymphocytes are stimulated with antigen they enlarge _____ into a ________ cell (called _________).

A

Enlarge 15um into a blast cell, lymphoblasts.

87
Q

What happens to lymphoblasts?

A

They further differentiate into effector cells or memory cells. (Plasma cells, T-helper cells, T-cytotoxic cells).

88
Q

Different maturational stages of lymphocytes can be distinguished by what?

A

By their expression of membrane CD molecules (CD= cluster of differentiation).

89
Q

Which CD markers are present on monocytes?

A

CD45+, CD14+

90
Q

Which CD markers are present on granulocyte?

A

CD45+, CD15+

91
Q

Which CD markers are present on T lymphocytes?

A

CD45+, CD3+

92
Q

Which CD markers are present on T helper lymphocytes?

A

CD45+, CD3+,CD4+

93
Q

Which CD markers are present on T cytotoxic lymphocytes?

A

CD45+, CD3+, CD8+

94
Q

Which CD markers are present on B lymphocytes?

A

CD45+, CD19+

95
Q

Which CD markers are present on natural killer cells?

A

CD45+, CD16+, CD56+, CD3-

96
Q

How long is the life span of effector cells?

A

Short lived - 2 weeks.

97
Q

How long is the life span of immunological memory?

A

Long lived - 3yrs or more for life.

98
Q

They are molecules by which we can identify T cells and divide them to subsets

A

T cell surface markers

99
Q

What are T cell surface markers required for?

A

Interactions between T cells and APC and for antigen recognition.

100
Q

What T cells receptors are present on activated T cells?

A

CD3
CD4 or CD8
CD2
CD28
And CD40L

101
Q

A kind of membrane on T cells that can specially bind to the antigenic peptide-MHC molecule complex

A

T cell receptor.

102
Q

List types of TCR?

A

1-Alpha beta TCR.
2- Gamma delta TCR.

103
Q

What is the structure of TCR?

A

1- extracellular region.
2- transmembrane region.
3- cytoplasmic region.

104
Q

What is the structure of extracellular region of TCR?

A

V region: V alpha and V beta antigen binding site.
CDR1, CDR2, CDR3.
C region: C alpha and C beta.

105
Q

What is the structure of transmembrane region of TCR?

A

Positive charge.

106
Q

What is the structure of cytoplasmic region of TCR?

A

Can’t transduce signal (3~12aa).

107
Q

What does CDR stand for?

A

Complementing determining regions.

108
Q

What is the co receptor of CD4 and CD8?

A

CD4: class II MHC.
CD8: class I MHC.

109
Q

CD4 and CD8 can also participate in _________ after TCR bind __________ specifically.

A

Signal transduction,
Antigen

110
Q

CD28 on resting or activated T cells binds to what on APC?

A

B7 (CD80/CD86).

111
Q

T cells can be turned on by stimulating which receptor?

A

CD28 receptor

112
Q

Which co-stimulatory receptor transmit a stimulatory signal to T cells?

A

CD28.

113
Q

What does CTLA-4 stand for?

A

Cytotoxic T Lymphocyte Antigen-4, CD152.

114
Q

What does CTLA-4 on activated T cells bind to?

A

B7.

115
Q

What co-stimulatory receptor sends an inhibitory signal to T cells and can turn it off?

A

CTLA-4.

116
Q

What is a CD2?

A

Co-stimulatory receptor, LFA-2, sheep red blood cell receptor.

117
Q

Where is CD2 expressed?

A

On 90% mature T cells (none on B cells).

118
Q

What is the ligand of CD2? And where is it expressed?

A

CD58 (LFA3), expressed on APC, RBC of human or sheep.

119
Q

List the functions of CD2?

A

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
Q

Where is CD40L present?

A

On activated TH cells.

121
Q

What is CD40L involved in?

A

Activation of B cells.

122
Q

What does CD40L bind to?

A

CD40 molecules on APCs.

123
Q

TH17 cells are another ________ __ _____ ______?

A

Effector T cell subset.

124
Q

What induces TH17 cells?

A

Induced from naive CD4+ or CD8+ T cells.

125
Q

What inhibits TH17 cells?

A

Inhibited by IL-2, IL-4 and IFN- gamma.

126
Q

What do TH17 cells produce?

A

IL-17 and IL-22.

127
Q

What does IL-17 induce?

A

Induces expression of G-CSF and chemokines for inflammation with neutrophils.

128
Q

What does IL-22 induce?

A

Induces anti-bacterial proteins.

129
Q

What are TH17 cells important for?

A
  • Anti-bacterial and anti-fungal infections;
  • Chronic autoimmune inflammation in skin, joints and CNS.
130
Q

Class of bacterial toxins (staphylococcal enterotoxins) & retroviral proteins that can activate very large numbers of T cells irrespective of their antigenic specificities?

A

Super antigens.

131
Q

List the 3 features of super Ags?

A

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
Q

What are BCRs?

A

Membrane immunoglobulin’s (mIgM and mIgD).

133
Q

What do BCRs consist of? (Shape)

A

Consists of 2 identical heavy chains and 2 identical light chains, linked by several disulfide bridges.

134
Q

What is the function of BCRs?

A

Recognize and bind to specific, intact antigens.

135
Q

List B-cell co-receptors complexes?

A

1- CD21 (CR2).
2- CD19.

136
Q

List function of CD21 (CR2)?

A

Enhancing the binding of BCR and antigen and pass activating signal to CD19.
EB virus receptor.

137
Q

List the function of CD19?

A

Transmit activating signal into B cell.

138
Q

List B-cell co-stimulatory receptor?

A

1-CD40.
2- B7.
3- MHC molecules.
4- Mitogen receptor.
5- Cytokine receptor.

139
Q

What does the CD40 on B cells bind to?

A

CD40L on activated T cell.

140
Q

List the functions of CD40?

A

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
Q

Where is B7 expressed on?

A

B cells or other APC.

142
Q

What is stimulatory B7? and what is the inhibitory B7?

A
  • B7-CD28 (stimulatory).
  • B7-CTLA-4 (inhibitory) (cytotoxic T lymphocyte antigen-4).
143
Q

List MHC molecules?

A

Class 1,2, MHC molecules.

144
Q

List mitogen receptors?

A

LPS.

145
Q

List cytokine receptors?

A

IL-4R, IL-5R, IL-6R.

146
Q

B-cell subpopulation is listed based on what?

A

According to expression of CD5 or not.
1- B1 cell (CD5+).
2- B2 cell (CD5-).

147
Q

List the different properties of B1 and B2, based on development, BCR, CD5, reproduction, Ab type, Ab avidity, function?

A

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
Q

List the functions of B cell?

A

1- produce the antibody ——— HI (humoral immunity).
2- present antigen ——— APC.
3- participate in immunological regulation.

149
Q

The measure of the total binding strength of an antibody at every binding site is termed what?

A

Avidity.

150
Q

Avidity is also known as what?

A

Functional affinity.

151
Q

Humoral immunity is the immunity to infection through the release of what?

A

Antibodies (immunoglobulins).

152
Q

What are antibodies and where are they produced from?

A

1- gamma globulins (proteins) called immunoglobulins (Ig).
2- produced by plasma cells (B-cells firstly turn into plasma cells).

153
Q

Abs constitute which % of total serum proteins?

A

20-25%

154
Q

Where are Abs located?

A

In the blood, extravascular tissues, secretions and excretions.

155
Q

What do Abs bind to and where?

A

Bind pathogenic microorganism and their toxins in extracellular compartments.

156
Q

List the 2 forms of Abs?

A

1- membrane bound Abs.
2- secreted Abs.

157
Q

____ lymphocytes use ______ _____ Abs to interact with ___.

A

B lymphocytes,
Membrane bound Abs,
Interact with Ags.

158
Q

What is the structure of Abs?

A

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
Q

L chain of Abs is attached to H chain by which bond?

A

Disulphide and non - covalent bonds.

160
Q

What are the 2 forms of L chain of Abs?

A

1- kappa (k)
2- lambda.

161
Q

Ig has which L chain form?

A

Either k or lambda, never both.

162
Q

What are the 2 regions of L and H chains of Abs?

A

1- Constant (Cl) (Ch) at C - terminal.
2- Variable (Vl) (Ch) at N - terminal.

163
Q

List the H chain for each Ig class?

A

1- IgM - mu (u).
2- IgA - alpha.
3- IgG- gamma (y)
4- IgE - Eplison (E)
5- IgD- delta.

164
Q

List the subclasses of the Ch region on an Ab?

A

1- Ch1.
2- Ch2.
3- Ch3.

165
Q

Regions on Abs are also called what?

A

Domains.

166
Q

What is the shape of the domains in Abs? And what bond stabilizes them?

A

Globular in shape.
Stabilized by intrachain disulphide bonds.

167
Q

Where are Ags binding site located on an Ab?

A

In the variable domains.

168
Q

Where is the hinge region located?

A

Segment of H chain between Ch1 and Ch2.

169
Q

Hinge region is flexible to what?

A

Ab.

170
Q

Hinge region is susceptible to what?

A

Enzymes and chemicals (e.g. pepsin and papain).

171
Q

List the 2 fragments of immunoglobulins?

A

1-Fab.
2-Fc.

172
Q

Fc fragment of Ab is composed of what?

A

Carboxy terminal of H chain.

173
Q

Fc fragment of Ab determines what?

A

Determines the biological properties of Ig molecule.

174
Q

Receptors for Fc portion is expressed by what?

A

1- mononuclear cells.
2- neutrophils.
3- NK cells.
4- eosinophils.
5- mast cells.

175
Q

Amino acid sequence in the _____ of L and H are not _______ ________.

A

Variable region,
Not uniformly variable.

176
Q

What does the hypervariable regions consist of?

A

Some highly variable (hypervariable) and some relatively invariable zones.

177
Q

Highly variable zones actually make contact with the epitope on an Ag and are called what?

A

Complementarity determining regions (CDRs).

178
Q

_________ is the longest and most variable of the three CDRs

A

CDR3.

179
Q

5 classes of Igs are based on what?

A

Constant region of heavy chains.

180
Q

______ subtypes of IgG and __ of IgA.

A

4 (IgG1-4),
2 (IgA1, IgA2).

181
Q

Which Ig has the highest number of antigen - binding sites

A

IgM (10)

182
Q

Which Ig has the heaviest molecular weight?

A

IgM (900,000 daltons).

183
Q

Which Ig has the lowest molecular weight?

A

IgG (500,000 daltons).

184
Q

Which Ig has the highest percentage of total antibody in the serum?

A

IgG (80%) (major).

185
Q

Which Igs have the lowest percentage of total antibody in the serum?

A

IgD and IgE (>1%).

186
Q

Which Ig can cross the placenta?

A

IgG.

187
Q

Which Igs fix complements?

A

IgG and IgM

188
Q

Fc of IgG binds to what?

A

Phagocytes.

189
Q

Fc of IgE binds to what?

A

Mast cells and basophils.

190
Q

What is the function of IgG?

A

Neutralization,
Agglutination,
Complement activation,
Opsonization,
And antibody-dependent cell-mediated cytotoxicity.

191
Q

What Ig is the major Ab of secondary response?

A

IgG.

192
Q

What is the function of IgM?

A

Neutralization,
Agglutination,
And complement activation.
The monomer form serves as the B cell receptor.

193
Q

Which Ig is 1st immune response?

A

IgM.

194
Q

What is the function of secretory IgA?

A

Neutralization and trapping of pathogens in mucus.

195
Q

What is the function of IgD?

A

B-cell receptor.

196
Q

What is the function of IgE?

A

Activation of basophils and mast cells against parasites and allergens.

197
Q

Which immune cells are large granular lymphocytes?

A

NK cells.

198
Q

Which immune cells is CD3 -ve, CD16 +ve and CD56 +ve?

A

NK cells.

199
Q

List the 4 functions of NK cells?

A

1- mainly in innate immunity.
2- kill tumor cells.
3- kill virus/bacteria infected cells (intracellular pathogens).
4- graft cells.

200
Q

How do NK cels recognize foreign Ags?

A

Independent of MHC.

201
Q

How are NK cells activated?

A

By cytokines (IL-2, IL-12, IL-15, IFN-alpha, IFN- beta).

202
Q

What do NK cells secret?

A

IFN- gamma.

203
Q

NK cells activated by IL-2 are also called what?

A

Lymphokine activated killer (LAK).

204
Q

What is LAK used in?

A

Cancer immunotherapy.

205
Q

How do NK cells differ from CTLs?

A

1- non-specific.
2- act spontaneously (no recognition nor activation).
3- not MHC restricted.
4- it is ADCC.

206
Q

List the 3 mechanisms of NK cells?

A

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
Q

Why do NK cells not kill normal cells?

A

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
Q

What are toll-like receptors (TLRs)?

A

Transmembrane proteins.

209
Q

Where are Toll-like receptors (TLRs) present on?

A

Macrophages, denderitic cells, epithelial cells.

210
Q

Why are TLRs an important part of innate immune system?

A

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
Q

List the molecules of the immune system?

A

1- antibodies.
2- complement.
3- cytokines.
4- interleukins.
5- interferons.

HD (14 decks)

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