Immunity Flashcards
1
Q
Do most microorganisms cause disease in humans?
A
Most don’t, but some do
2
Q
What are pathogens?
A
Disease causing microorganisms
3
Q
What do pathogens include?
A
- Protozoa
- Bacteria
- Viruses
- Fungi
- Worms
4
Q
What are both humans and pathogens made from?
A
Proteins, carbohydrates and lipids
5
Q
What are the roles of protein in pathogens?
A
- Nutrient acquisition
- Reproduction
- Locomotion
- Respiration
6
Q
How do humans and pathogens differ in their proteins?
A
They posses radically different proteins, that allow them to survive in their respective niches
7
Q
What do different proteins have?
A
Different amino acid sequences
8
Q
What is the significance in the difference in amino acid sequences?
A
The immune system detects this difference
9
Q
What is damage to the host an inevitable consequence of?
A
Breaking through barriers in order to gain access to regions that are most prosperous
10
Q
What is an inevitable consequence of damage to the barriers?
A
Alert
11
Q
What is the first barrier to infection?
A
Epithelia
12
Q
What does epithelia do to prevent infection?
A
Keep body clear of pathogens
13
Q
How do we facilitate the clearance of pathogens from epithelial surfaces?
A
- Rapid epithelial regeneration
- Blinking
- Flow of tears
- Ear wax
- Nasal hairs
- Coughing
- Sneezing
- Mucociliary escalator
- Vomiting
- Digestive enzymes
- Peristaltic gut movement
- Regular urine flow
14
Q
How quickly do epithelial cells function on contact with a pathogen?
A
Within seconds
15
Q
Essentially, what is epithelium?
A
A mechanical, selectively permeable barrier between the ‘outside’ and the ‘inside’
16
Q
What may epithelial cells posses?
A
Motile cilia
17
Q
Can epithelial cells renew?
A
Yes, rapidly
18
Q
What is the purpose of motile cilia on epithelial cells?
A
Keep surface free of bacteria
19
Q
What do epithelial cells produce?
A
- Natural antibodies
- Cytokines
- Chemokines
- May produce mucins
20
Q
What kind of natural antibodies do epithelial cells produce?
A
Cationic antibacterial peptides
21
Q
Give 2 examples of cationic antibacterial peptides?
A
- Defensins
- Cathelicidins
22
Q
What are cytokines?
A
Proteins that alter the behaviour of other cells
23
Q
What are chemokines?
A
Proteins that attract other cells by gradients
24
Q
Where to epithelial cells transport antibodies to and from?
A
From inside to outside
25
What is the primary role of epithelial cells?
To block the entry of microorganisms
26
What must be done for pathogens with non-self proteins to break through the epithelial barrier?
They must damage it
27
What happens to epithelial cells on contact with microorganisms?
They are activated
28
What do activated epithelial cells produce?
Chemokines and cytokines
29
What is the result in the production of chemokines and cytokines?
A much more permeabilised epithelium
30
What is the result of a more permeabilised epithelium?
#NAME?
31
What is the result of opsonisation of foreign materials?
Pathogens more readily phagocytosed
32
What happens after a pathogen is phagocytosed?
It raises a specific response
33
What is the result of the specific response to a phagocytosed pathogen?
Interaction with other cells of the innate and adaptive immune system
34
What promotes vascular permeability?
Many inflammatory mediators- immunoglobulin and complement
35
What is the result of vascular permeability?
Mediators are leaked into the inflamed site through the endothelial cells lining blood vessels
36
What do inflammatory mediators do?
- Increase permeability
- Increase migration of macrophages, neutrophils and lymphocytes into tissue
- Increases SA to volume ratio
37
What does increased permeability allow?
Increased fluid leakage from blood vessels and extravasation of antibodies and complement at site of infection
38
What is the result of increased migration of macrophages, neutrophils and lymphocytes?
Increases microbicidal activity
39
What is the result of an increased SA to volume ratio?
Better gas exchange
40
What is the result of action of inflammatory mediators?
Allows for immunofunction to be increased
41
What is inflammation a response to?
Infection
42
What does inflammation lead to?
- Heat
- Swelling
- Redness
- Pain
- Loss of function
43
What is the purpose of inflammation?
Protects area from further damage
44
What is the innate immune response?
Inbuilt immunity to resist infection
45
When is innate immunity present from?
Birth
46
Is innate immunity specific?
No
47
Is innate immunity enhanced by secondary exposure?
No
48
What kind of components does innate immunity use?
Cellular and humoral
49
Is innate immunity effective alone?
No, poorly effective without adaptive immunity
50
What is innate immunity involved in?
Triggering and amplification of adaptive immune response
51
What is adaptive immunity?
Immunity established to adapt to infection
52
How is adaptive immunity obtained?
Learnt by experience
53
What does adaptive immunity confer?
Pathogen-specific immunity
54
Is adaptive immunity enhanced by second exposure?
Yes
55
Does adaptive immunity have memory?
Yes
56
What kind of components does adaptive immunity use?
Cellular and humoral
57
Is adaptive immunity effective without innate immunity?
No
58
What do antibodies reflect?
Infections to which an individual has been exposed to already
59
What are antibodies diagnostic for?
Infection
60
How has the adaptive immune system evolved?
#NAME?
61
What is the importance of innate immunity implied by?
- Rarity of inherited deficiencies in innate immune mechanisms
- Considerable impairment of protection when deficiencies in innate immunity occurs
62
What cells are involved in innate immunity?
- Macrophages and monocytes
- Neutrophils
- Basophils
- Eosinphils
- Natural killer cells
63
What are the roles of macrophages and monocytes?
- Phagocytosis
| - Presentation to lymphocytes
64
What are the roles of neutrophils?
- Phagocytic
| - Anti-bacterial
65
What is special about polymorphonucleur neutrophils?
They have 5 lobes to their nuclei
66
What are the roles of mast cells and basophils?
#NAME?
67
What are the roles of eosinphils?
- Anti-parasite
| - Causes allergies
68
Describe the nucleus of lymphocytes?
It almost fills the cytoplasm
69
What kind of cells are phagocytes?
#NAME?
70
What is meant by a phagocyte?
A cell able to engulf and destroy bacteria, extracellular viruses and immune complexes
71
What is phagocytosis?
Active engulfment of particles into a phagosome
72
What is formed form a phagosome and a lysosome?
Phagolysosome
73
What occurs in a phagolysosome?
Digestion
74
What happens to neutrophils in healthy tissues?
They are normally excluded
75
Why are bites taken so seriously?
Because the mouth is the most contaminated site in the body, and the microbes in the mouth can enter the wound when bitted
76
What are neutrophils specialised for?
Working under anaerobic conditions
77
Why are neutrophils adapted for working anaerobic conditions?
Because these prevail in damaged tissues
78
When does neutrophil arrival occur in an inflammatory response?
First event
79
What happens once a neutrophil has been activated?
They become unable to synthesise new granules
80
What happens once all granules have been used up?
The neutrophil dies
81
What do patients with neutrophil deficiencies suffer from?
Recurrent infection, often by microbes of the normal commensal flora
82
Why do patients with neutrophil deficiencies often suffer from recurrent infections?
Because they have limited phagocytic action
83
What can phagocytes sometimes to?
Release their lysosome contents on the outside of pathogens
84
Why would phagocytes release their lysosomal contents onto the surface of pathogens?
If they were too big to digest
85
What binds to neutrophil receptors?
Bacteria
86
What does bacterial binding to neutrophil receptors induce?
Phagocytosis and microbal killing
87
What do neutrophils have for phagocytosis?
Elaborate receptors
88
What do neutrophils do to the bacteria bound to them?
Engulf and digest
89
What do CD14 and CR4 bind to?
Bacterial lipopolysaccharide (LPS)
90
What do macrophages do?
Phagocytose microbal, or damaged and unwanted cells
91
What do macrophages release?
A variety of cytokines
92
What are the cytokines released by macrophages important for?
Innate and adaptive immunity
93
Do macrophages live long?
Yes
94
Why are macrophages long-lived?
Because they continue to generate more lysosomes as needed
95
What do macrophages act as?
Professional antigen presenting cells (APCs)
96
Where are APCs important?
In the development of adaptive immunity
97
What do APCs do?
Show antigens to T lymphocytes for their action
98
What is opsonisation?
The coating of an microorganism by antibodies or complement to render in recognisable as foreign by phagocytes
99
What does opsonisation enhance?
Phagocytosis
100
When are encapsulated bacteria more efficiently phagocytosed?
When coated with antibody and C36
101
What can encapsulated bacteria not be engulfed by?
Neutrophils
102
What does antibody bound to bacteria activate?
Complement binding of C3b to bacteria
103
What is engulfment of bacteria by neutrophils mediated by?
Fc receptors and complement receptors
104
What do granules fuse with?
Phagosomes
105
What happens when granules fuse with phagosomes?
Toxic oxygen metabolites that kill bacteria released
106
What are natural killer (NK) cells a part of?
Innate immune system
107
Are NK cells T or B cells?
Neither
108
Do NK cells have classical antigen receptors?
No
109
What do NK cells do?
Recognise and kill abnormal cells
110
Give an example of an abnormal cell NK cells can kill?
Tumour cells
111
What is the result of NK cells killing tumour cells?
Stops cancer developing
112
What do NK cells do in virus-infected cells?
Directly induce apoptosis
113
How do NK cells induce apoptosis in virus-infected cells?
By pumping proteases through pores that they make in target cells
114
What are NK cells similar to?
Cytotoxic T cells
115
How do NK cells differ from cytotoxic T cells?
They have no specific T cell receptors
116
What do NK cells provide?
Innate immunity against intracellular infections
117
What happens in people lacking NK cells?
They suffer from persistent viral infections, particularly herpes virus
118
What leads to NK cell activation in most cells?
IFNα and IFNß
119
What leads to NK cell activation in macrophages?
IL-12 and TNFα
120
What do NK cells provide regarding a virus infection?
An early response
121
What do viral infections induce?
Cells to secrete a burst of cytokines
122
What do cytokines induce?
The proliferation and activation of NK cells
123
What happens while NK cells act?
A slower cytotoxic T cell response develop which helps to clear the infection
124
What are the secretory molecules of the innate response also known as?
Humoral components
125
What are the humoral components on the innate immune respose?
- Transferrin and lactoferrin
- Interferon
- Lysozyme
- Fibronectin
- Complement components and their products
- TNF-α
126
What does transferrin and lactoferrin do?
Deprives microorganisms of iron
127
What does interferon do?
Inhibits vital replication and activates other cells which kill pathogens
128
Where are lysozymes found?
In serum and tears
129
What do lysozymes do?
They break down the bacterial cell wall of some gram+ bacteria
130
What are lysozymes in synergism with?
Antimicrobal peptides
131
What does fibronectin do?
Opsonises bacteria, and promotes their rapid phagocytosis
132
What do complement proteins and their products cause?
Destruction of microorganism, directly or with help of phagocytic cells
133
What does TNF-α do?
Suppresses viral replication and activates phagocytes
134
Why is the complement system so named?
Because is was discovered as heat-labile components which complemented or enhanced the oponising effects of antibody
135
What does the complement system do?
Marks pathogens for destruction
136
How does the complement system mark pathogens for destruction?
By covalently binding to their surface
137
Evolutionarily, what came first, the complement system or the antibody response?
The complement system
138
What did the antibody response evolve to do?
Enhance the mechanism of complement activation and phagocytosis
139
Where are complement proteins found?
Ubiquitous in the blood and lymph
140
How long after an infection begins can the complement system be used?
Immediately
141
What does an antibody do to the complement system?
Enhances complement activation
142
What are the complement components?
C1-C9
143
How do different complement proteins differ from each other?
They have different functions
144
What are C5a, C3a and C4a responsible for?
Recruitment of inflammatory response
145
What is recruitment of inflammatory cells important for?
Recruitment for host defence against infection
146
What is C3b responsible for?
Opsonisation
147
What is responsible for the direct killing of pathogens?
MAC (membrane attack complex) using C5-C9
148
What does the MAC do?
Assembles to make a pore in the pathogen membrane
149
What does the MAC assemble?
- C5b binds to C6 and C7
- C5b, 6 and 7 complexes bind to membrane via C7
- C8 binds to the complex, and inserts itself into the membrane
- C9 molecules bind to the complex and polymerise
- 10-16 molecules of C9 bind to form a pore in the membrane
150
What happens if there is a deficiency in C1, 2 or 4?
Immune complex disease (type III)
151
What happens if there is a deficiency in C3?
Recurrent bacterial infection
152
What happens if there is a deficiency in C5-9
Recurrent Neisserial infection
153
What do T and B lymphocytes respond to?
Antigens
154
What are antigens?
Molecules that elicit a specific immune response when introduced to the tissues of an animal
155
What does the common lymphocyte precursor (CLP) give rise to?
T cells and B cells
156
Where do T cells develop?
Thymus
157
Where do B cells develop?
Bone marrow
158
What to T cells give rise to?
T helper cells (Th) and cytotoxic T lymphocytes (CTL)
159
What do Th cells do?
Activate B cells and macrophages
160
What do CTLs do?
Kill virus infected cells
161
What do B cells give rise to?
Plasma cells
162
What do plasma cells do?
Produce antibodies
163
What happens when B cells are activated?
They get much bigger with lots of RER
164
What is true of T and B cells until they encounter an antigen?
They are essentially inactive
165
What do T and B cells express?
Antigen receptors
166
What is the B cell receptor?
A membrane bound antibody surface immunoglobulin
167
What is the T cell receptor?
A distinct molecule called a T cell antigen receptor
168
What does each antigen receptor bind to?
A different antigen
169
How many antigen specificity does each cell have?
1
170
What does the T cell receptor resemble?
A membrane bound Fab fragment
171
What are 3 main ways antibodies protect the host from infection?
- Neutralisation
- Opsonisation
- Complement activation
172
What happens in antibody neutralisation?
Prevents bacterial adherence, stopping it binding to the cell
173
What does each lymphocyte express?
A single antigen receptor specificity
174
How many lymphocytes are there in the body?
Millions
175
What does each naive lymphocyte bearing a unique receptor represent?
A potential progenitor of a genetically identical clone of daughter cells
176
What does the clonal distribution of antigen receptors mean?
That lymphocytes of a particular specificity will be too infrequent to mount an effective response
177
What is the purpose of clonal selection?
It raises the clonal frequency of cells with a particular antigen specificity
178
What does antigen interaction lead to?
Lymphocyte activation
179
What do daughter cells of activated lymphocytes bear?
Identical antigen specificity to the parent cell
180
What does a B lymphocyte do on activation?
Attaches to foreign material
181
What does the attachment of B lymphocytes to foreign material cause?
Clonal expansion
182
What does clonal selection induce?
Proliferation and increase in effector frequency
183
What are the phases of the adaptive immune response?
- Recognition phase
- Activation phase
- Effector phase
- Decline homeostasis
- Memory
184
What happens during the recognition phase?
Clonal selection
185
What happens during the activation phase?
Clonal expansion
186
What happens during the effector phase?
Differentiation to effector cells
187
What does the clonal nature of the adaptive immune response allow for?
Immune logical memory
188
What must happen for T helper cells to be able to ‘see’ something foreign?
Presentation to them by antigen presenting cell
189
What must happen for B cells to become plasma cells?
Must be given permission by T helper cells
190
What does almost every cell type bear?
MHC class 1
191
What is the result of almost every cell type possessing MHC class 1?
Can present endogenous antigen to cytotoxic T cells
