Immunology Flashcards
(74 cards)
1
Q
What is innate immunity?
A
Non-specific immune response to pathogens
2
Q
What is adaptive immunity?
A
Specific acquired ammunity
3
Q
What cells are polymorphonuclear leukocytes?
A
- Neutrophil
- Eosinophil
- Basophil
4
Q
What cells are mononuclear leukocytes?
A
- Monocytes
- T cells
- B cells
5
Q
What are the cells of the immune system?
A
- Neutrophils (65%)
- Eosinophil (5%)
- Basophil (0.2%)
- Monocytes (5%)
- T cells (10%)
- B cells (15%)
- Mast cells
- Natural killer cells (15%)
- Dendritic cells
6
Q
What are the two main types of intracellular granules that neutrophils have?
A
- Primary - myeloperioxidase, muramidase, acid hydrolases, proteins
- Secondary - lactoferrin, lysosome
7
Q
What receptors do monocytes have on their cell wall?
A
- Fc
- Complement
- PRR
- Toll-like
- Mannose
- Scavenger
8
Q
What receptor is expressed on eosinophils?
A
CD125 receptor
9
Q
What is in eosin granules?
A
Major Basic Protein - this is toxic to helminth worms and activates neutrophils and induces histamine release from mast cells and promotes bronchospasms.
10
Q
What are mast cells?
A
- Tissue cells which are similar to basophils
- Express IgE receptor, binding to this receptor causes degranulation of histamine
11
Q
What are the four types of T cell and their role?
A
- T helper 1 – CD4 help immune response to intracellular pathogens
- T helper 2 – CD4 help produce antibodies to extracellular pathogens
- Cytotoxic T cell – CD8 can kill directly
- T regulatory (FoxP3 receptor) – regulate immune response and dampen the response
12
Q
What receptors do B cells have?
A
CD19 and CD20
13
Q
What cells do B cells mature into?
A
Plasma cells - these produce antibodies
14
Q
What is the role of natural killer cells?
A
To recognise and kill virus infected cells and tumour cells
15
Q
What are the three actions of the compliment pathway?
A
- Direct lysis
- Attract more leukocytes to the site of infection (chemotaxis)
- Coat invading organisms with C3b (opsonisation)
16
Q
What are the 5 different types of antibodies?
A
- IgG
- IgA
- IgM
- IgD
- IgE
17
Q
Definition of antibody
A
Protein produced in response to an antigen. It can only bind with the antigen that induced its formation.
18
Q
Definition of antigen
A
Molecule that reacts with preformed antibodies and specific receptors on T and B cells
19
Q
Definition of epitope
A
Part of an antigen that binds to the antibody/receptor binding site
20
Q
Definition of affinity
A
Measure of the binding strength between the epitope and an antibody binding site.
21
Q
What are cytokines and four examples of cytokines:
A
Signalling proteins secreted by immune and non-immune cells
- Interferons
- Interleukins
- Colony stimulating factors
- Tumour necrosis factor
22
Q
What are chemokines?
A
Group of 40 proteins which direct movement of leukocytes and other cells from the blood stream to tissue or lymph organs
23
Q
What components make up the innate immune system?
A
Anatomical barriers Mucous membranes Physiological barriers Phagocytic cells Serum proteins (complement)
24
Q
What is the inflammatory process following tissue damage?
A
- Stop the bleeding – coagulation
- Acute inflammation – leukocyte recruitment
- Kill pathogens, neutralise toxins, limit pathogen spread
- Clear pathogens – phagocytosis
- Proliferation of cells to repair damage
- Remove blood clot and remodel the extracellular matrix
- Re-establish normal structure and function of tissue
25
What are the two killing pathways present in neutrophils and macrophages?
1. O2 independent - lysosomes, defensins, TNF, pH
| 2. O2 dependent - free radicals
26
What is neutrophil extravasion following bacterial infection?
Movement of neutrophils from blood vessels into surrounding tissue in response to chemokine secretion from tissue macrophages
27
Explain the process of phagocytosis:
1. Pathogen is recognised by cell surface receptors on macrophage
2. Macrophage endocytoses the pathogen into a phagosome
3. The phagosome fuses with a lysosome to form a phagolysosome
4. Pathogen is degraded in the phagolysosome
28
What is passive immunisation
The transfer of preformed antibodies between humans
29
Two examples of passive immunisation
Transfer of maternal antibodies across the placenta
| Transfer of maternal antibodies through breast milk
30
One example of unnatural immunisation
Treatment of immunocompromised patients with immunoserum
31
What is a disadvantage of passive immunisation?
It does not elicit immunological memory, merely neutralises toxins with the finite amount of anti-toxins
32
Where can passive immunisation be used clinically?
To treat snake bites, jelly fish stings
| As a prophylaxis to prevent an infection following exposure to hepatitis/measles/rabies
33
What is active immunisation?
Manipulation of the immune system to generate a persistent protective response against pathogens by safely mimicking natural infection.
34
What is the predominant immunoglobulin in primary exposure to a pathogen?
IgM - low-affinity non-specific
35
What is the predominant immunoglobulin in secondary exposure to a pathogen?
IgG - high-affinity highly-specific
36
What are the 5 types of vaccine design?
1. Whole organism - live attenuated or killed inactivated
2. Subunit
3. Synthetic peptide
4. DNA vaccines
5. Engineered virus - recombinant vector vaccines
37
What is a vaccine adjuvant?
Substances added to a vaccine to stimulate the immune system
38
Why do we need the adaptive immune system?
- Some microbes can evade the innate immune system
- Intracellular viruses and bacteria hide in cells
- Immunological memory
39
What cells are involved in the immune system?
T cells and B cells
40
Where do T cells mature?
Thymus
41
Where do B cells mature
Bone marrow
42
What other molecules are required for the adaptive immune system to function?
- Major histocompatibility complex
- Intrinsic/endogenous/intracellular antigens
- Extrinsic/exogenous/extracellular antigens
43
What type of antigens do T cells respond to?
Intracellular presented antigens (not soluble antigens)
44
What is T cell selection?
The process of T cells which recognise self-tissue being killed in the foetal thymus to prevent autoimmunity
45
What other immune structure is a T cell receptor similar to?
Fab region of an antibody
46
How are intracellular viruses processed by nucleated cells and presented to T cells?
Viral proteins are broken down and presented on the cell surface alongside MCH1. These are recognised by CD8 T cells and destroyed.
47
How are CD8 cells activated?
WHen they react with MHC1/peptide the CD8 cells is activated into a cytotoxic T cell. This produces proteolytic granules and released perforins and granulysin which damage the infected cell.
48
How are CD4 cells activated
APC presents the antigen via MHC2. Interleuekin 12 produced by APC causes activation of CD4 cell into Th1 cell.
Production of interleukin 2 by the T cell stimulates activation into Th2 cell ???
49
What is clonal expansion?
Replication and proliferation of Th2 cells
50
What is humoral adaptive immunity?
Antibody mediated immunity
51
Are B cells antigen presenting cells?
Yes
52
What is the process of gaining humoral immunity?
- Antigen interacts with B cell receptor
- B cell ingulf antigen and process antigen
- B cell presents antigen alongside MHC2
- T cell receptor (Th2) binds to B cell and secrete IL4,5,10,13
- B cells either differentiate into plasma cells or memory cells
- Plasma cells produce more antibodies
- Memory cells remain in the circulation and are activated into plasma cells
53
What is the neutropaenic phase in cancer patients following chemotherapy?
The 2-4 week phase were patients don't have any circulating neutrophils
54
What is a pattern recognition receptor?
A molecule that recognises patterns on harmful foreign bodies that stimulates an immune response despite no previous exposure.
55
What components/features of gram -ve cell walls make them identifiable by PRRs?
- Lipopolysaccharides
- Peptidoglycans
- Hydrophobicity
56
What components/features of gram +ve cell walls make them identifiable by PRRs?
- Acidic polysaccharides
| - Peptidoglycans
57
What are the secreted and circulating PRRs?
```
Antimicrobial peptides (secreted in lining fluids) - defensins, cathelicidin
Lectins and collectins e.g. mannose binding lectin, work by binding to carbohydrates/lipids in microbe walls and activating complement and phagocytosis
Pentraxins e.g. C-Reactive Protein which have antimicrobial actions (interact with C protein of pneumococci and activate complement)
```
58
What are the cell associated PRRs?
- Toll-like receptor
- Mannose binding receptor on macrophages (recognise fungi)
- Dectin-1 found on phagocytes (recognise beta glucans in fungi)
- Scavenger receptor on macrophages
- Nod-like receptor
- Rig-like receptor
59
What does TLR1/2 recognise?
Gram +ve bacteria lipopeptides
60
What does TLR3 recognise?
Double stranded viral RNA
61
What does TLR4 recognise?
Lipopolysaccharides on gram -ve bacteria, viral proteins, pneumolysin
62
What does TLR5 recognise?
Flagellin (bacterial motor protein)
63
What does TLR2/6 recognise?
Gram +ve lipopeptides
64
What does TLR7 recognise?
Single stranded RNA
65
What does TLR8 recognise?
Single stranded RNA
66
What does TLR9 recognise?
Bacterial DNA as there is an extra methyl group on cytosine residues of bacterial DNA
67
What do TLRs do?
Activate pro-inflammatory gene transcription and promote antiviral immunity through enhancing NF-kappaB driven inflammation and stimulating interferon release
68
How do nod-like receptors detect intracellular pathogens?
Detect peptidoglycans and muramyl dipeptide.
| NOD2 - recognises muramyl dipeptide which is a breakdown product of peptidoglycan in gram +ve cell walls
69
What disease arises from over-active NOD2 receptor?
Blau's syndrome - chronic granulomatous inflammation of the skin and eyes
70
What disease arises from under-active NOD2 receptor?
Chron's disease
71
What are Rig-like helicase receptors?
Receptors which detect double stranded viral RNA and DNA.
| They stimulate interferon production facilitating an antiviral response
72
Why does the innate immune system also deal with tissue damage?
Innate immune system is also triggered by damage molecules released from the body.
73
What are cellular damage molecules?
- Fibrinogen
- Hyaluronic acid
- Tenascin C
- HMGB1
- mRNA
- Heat shock proteins
- Uric acid
- Stathmin
74
Where can TLR receptor agonists be used clinically?
- Vaccine adjuvants to stimulate an immune response
| - Skin cancer ointments to elicit an immune response against the cancerous cells
