Immunology Flashcards
1
Q
State the four hallmarks of immune deficiency
A
- serious infection
- persistent infection
- unusual infections
- recurrent infections
2
Q
Name eight features of immunodeficiency
A
- weight loss
- severe skin rash
- chronic diarrhoea
- mouth ulceration
- unusual autoimmune disease
- lymphoproliferative disorders
- cancer
- family history
3
Q
How can immunodeficiencies be classified?
A
primary & secondary
4
Q
Give an example of physiological cause SID
A
extremes of life
5
Q
Give an example of an infection causing SID
A
HIV & Measles
6
Q
Name a treatment intervention that causes SID
A
Chemo & Corticosteroids
7
Q
What types of malignancy can cause SID?
A
Malignancy of the immune system & Metastasis
8
Q
What biochemical/nutritional disorders cause SID?
A
Malnutrition & diabetes
9
Q
Name three common upper respiratory tract infections caused by PIDs
A
sinusitis
otitis media
laryngeal angioedema
10
Q
Name four common lower respiratory tract infections caused by PIDs
A
malignancies
interstitial lung disease
pneumonia
bronchitis/bronchiectasis
11
Q
Give two examples of PIDS that cause significant complications
A
- primary antibody deficiency
- complement system disorders
12
Q
Name the types primary antibody deficiency
A
- selective IgA deficiency
- common variable immunodeficiency
- specific antibody deficiency
- X linked agammaglobulinemia
13
Q
What other disease can these PIDs lead to?
A
Pneumonia
14
Q
Define neutropenia
A
abnormally low concentration of neutrophils in the blood
15
Q
What treatment can cause neutropenia?
A
Chemotherapy and radiotherapy for leukaemia
16
Q
State four potential problems with neutrophils
A
- defects in neutrophil development
- defects in neutrophil transendothelial migration
- defects in neutrophil killing
- defects in macrophage killing
17
Q
What is the problem in a neutrophil development defect?
A
The final differentiation stage, the GCSF gene. SCN type 1 is most common and is inherited in an autosomal dominant manner.
18
Q
What do neutrophil development defects cause?
A
- severe chronic neutropenia
- accumulation of precursor cells in bone marrow
- recurrent bacterial/fungal infections
19
Q
What is the treatment for neutrophil development defects?
A
Recombinant GCSF which reduces infections and improves survival. But there is an increased risk of AML and myelodysplasia
20
Q
How do defects in transendothelial migration arise?
A
failure to recognise activation markers expressed on endothelial cells neutrophils are mobilised and cannot exit the bloodstream
21
Q
What are the clinical features of defects in transendothelial migration?
A
recurrent fungal/bacterial infections
22
Q
What happens to blood count and at the site of infection when defects in TEM occur?
A
High neutrophils but no pus
23
Q
What are TEM defects caused by?
A
defect in CD18 gene
24
Q
Describe defects in neutrophil killing
A
chronic granulomatous disease is a deficiency of the intracellular killing mechanism of phagocytes resulting in an inability to generate oxygen/nitrogen free radicals and leads to impaired killing of micro-organisms
25
What are the clinical features of defects in neutrophil killing?
- recurrent deep bacterial infections
- recurrent fungal infections
- failure to thrive
- lymphadenopathy
- granuloma formation
26
Describe defects in macrophage killing
Some intracellular hide from the immune system by locating within cells some even hide within immune cells especially macrophage
27
What is the treatment for phagocyte deficiencies ?
- immunoglobulin replacement therapy
- aggressive management of infection
- definitive therapy (stem cell transplant, specific treatment, gene therapy)
28
How do B cells normally develop?
stem cells > lymphoid progenitors > Pro B Cells > Pre B cells > B cells with different antigen specificities
29
How are B cells activated?
They express opsonins and secrete antibodies. TFH cells have TCR peptides which recognise MHC II on B cell. This causes the B cell to differentiate from IgM to IgG, IgA & IgE
30
How do T cells normally develop?
In the bone marrow
stem cells> lymphoid progenitors > pre cells
In the thymus
pre t cells > thymocytes > CD4 & CD8 T cells
31
How are T cells activated?
Dendritic cells present MHC Class 1 & 2 leading to clonal proliferation and differentiation. The cytotoxic T cells then go on to kill infected tissue cells.
32
What 4 defects can happen in leukocyte development?
1. defects in haemopoietic stem cells
2. defects in lymphoid precursor cells
3. defects in thymocyte development
4. defects in B cell development
33
Define reticular dysgenesis
failure to produce all leukocytes which is fatal unless corrected with HSC transplantation
34
What is severe combined immunodeficiency?
collection of genetic immunodeficiency disorders involving both B and T cells
35
When do symptoms of SCID begin?
once maternal antibodies no longer protect the patient
36
What are the symptoms of SCID?
- persistant diarrohoea
- failure to thrive
- infections
- unusual skin disease
- family history of early infant death
37
What are the treatment options for SCID?
- prophylactic (avoid infections)
- definitive (involves stem cell transplant from HLA)
- gene therapy (up and coming)
38
Give an example of defects in thymocyte development
DiGeorge Syndrome - results in failure to produce CD4 + and CD8+ T cells
39
What are the symptoms of DiGeorge syndrome?
- Structural abnormalities ; eyes to the chest
- Absence of thymus
- Loss of parathyroid gland (leading to loss of calcium homeostasis)
- recurrent viral infections
40
Why do patients with DiGeorge have recurrent viral infections?
The absence of cytotoxic T cells means infected cells are not killed. TH1 cells will not activate macrophage and CD4+ cells cannot help B cells make antibodies
41
What is the management for DiGeorge syndrome?
- correct metabolic/cardiac abnormalities
- prophylactic antibodies
- early & aggressive treatment of infection
- immunoglobulin replacement
42
Give an example of defects in B cell development
X linked agammaglobulinaemia - a gene on the X chromosome encodes for an enzyme BTK where the defect is found
43
What are the typical presentations of X linked agammaglobulinaemia?
- upper and lower resp infections
- diarrhoea
- cellulitis
- meningitis
- sepsis
44
What type of bacteria are infections usually caused by?
Gram positive as the phagocytes cannot bind very well due to the hidden PAMPs in the polysaccharide layer
45
Describe defects in T cell effector functions
T helper cells will not respond to IL12 so therefore won't produce interferon gamma to stimulate macrophage
46
Name two types of defects in B cell effector functions
- hyper IgM syndromes
| - selective IgA deficiencies
47
Describe hyper IgM syndromes
severe reduction in serum IgG & IgA but normal IgM and normal number of B cells. Due to inability of antigen activated cells to switch antibodies
48
Define hypersensitivity diseases
immune response that results in bystander damage to the self
49
How can hypersensitivity diseases be classified?
Type 1 - 4
50
What is type 1 characterised by?
Allergy - enhanced sensitivity to normal innocuous substances
IgE mediated antibody response to external antigen
51
Give six examples of common allergens
1. house dust mite
2. pollen & animal dander
3. foods
4. drugs
5. latex
6. bee & wasp venom
52
When the allergen presents what cells does it activate?
- Dendritic cell
| - B cell
53
Describe the pathway following activation of dendritic cells
1. dendritic cells activate CD4+ T cells
| 2. CD4+ differentiate into TFH and TH2 cells
54
What do the TH2 cells do?
Produce IL 5 to activate eosinophils
| Produce IL 4,5,13 to stimulate IgE production from B cells
55
What does the TFH cell do?
Binds to MHC class 2 receptor on B cells leading to IgM plasma cell production and IgE production
56
What do mast cells and eosinophils express receptors for?
Fc region of IgE antibody
57
Name some products of mast cells
- mediators (histamine, tryptase, heparin)
- leukotrienes, prostaglandins
- pro-inflammatory cytokines
58
State four effects of mast cells production
- increased blood flow
- contraction of smooth muscle
- increased vascular permeability
- increased secretions at mucosal surfaces
59
Name seven clinical features of type 1 hypersensitivity
1. asthma
2. urticaria
3. angioedema
4. allergic rhinitis
5. allergic conjunctivitis
6. diarrhoea & vomiting
7. anaphylaxis
60
State six ways to manage type 1 hypersensitivity
1. avoid allergen
2. block mast cell activation
3. prevent effects of mast cell activation
4. anti-inflammatory agents
5. management of anaphylaxis
6. immunotherapy
61
What is type 2 hypersensitivity?
normal adaptive immune responses lead to the production of IgG/M antibodies to self antigens
62
Name three immunological mechanisms of type 2 hypersensitivity
- complement activation
- opsonisation & phagocytosis
- ADCC via NK cells or eosinophils
63
Give an example of type 2 hypersensitivity
Goodpasture's Syndrome - affects the lungs and kidney's due to the presence of auto reactive antibodies to alpha 3 chain of collagen in basement membranes.
64
What causes Goodpastures's syndrome?
Smoking in a person with genetic susceptibility
65
In type 2 hypersensitivity. What are the three consequences of B cells producing antibodies directed against cell membrane proteins?
1. Activation of complement & osmotic lysis of the cell
2. NK cell and eosinophil activation = antibody dependent cellular cytotoxicity
3. Antibody acts as opsonin for phagocytes leading to phagocytosis of antigen cells
66
Name three mechanisms of type 3 hypersensitivity
1. immune complexes are deposited in the walls of blood vessels
2. immune complexes activate complement and attract inflammatory cells
3. Enzymes released from neutrophils cause damage to endothelial cells of basement membrane
67
What is the management for type 3 hypersensitivity?
- corticosteroids (decrease inflammation)
| - immunosuppression (decrease antibody production)
68
What is type 4 hypersensitivity?
Delayed type hypersensitivity
69
Define autoimmunity
the presence of immune responses against self tissue/cells
70
Define self tolerance
non-responsiveness of lymphocytes to specific self antigens
71
Define central tolerance
deletion of self reactive lymphocytes in primary lymphoid tissue
72
Define peripheral tolerance
inactivation of self reactive lymphocytes in peripheral tissues that escape central tolerance
73
What is the significance of Treg cells?
They are involved in lymphocyte suppression and are activated by IL 10 and TGF beta
74
How does a autoimmune disease/phenomena arise?
Genetic susceptibility & initiating event leads to the breakdown of immune tolerance to self antigens
75
What factors contribute to autoimmune disease?
- genes
| - environment
76
What are monogenic disorders?
Single gene defects causing autoimmune disease
77
Describe IPEX syndrome
presents early in childhood and is characterised by overwhelming systemic autoimmunity
78
What are the symptoms of IPEX?
Severe infections, intractable diarrhoea, eczema, type 1 diabetes
79
What is the treatment for IPEX?
stem cell transplant or supportive care
80
Describe the pathogenesis of IPEX
X linked so only males are affected.
Mutation on FOXP3 gene which is essential for the development of regulatory T cells
Failure of peripheral tolerance mechanisms
81
What is another name for MHC molecules?
HLA molecules
82
Describe HLA/MHC molecules
```
Polymorphic in order to maintain diversity of antigen responsiveness at population & individual level
Single class 1/2 molecules is able to present to many different peptides
```
83
Name three groups that are at high risk of autoimmunity
Pregnant women
People with family history
People of certain race/ethnic background
84
State four aspects of the environment that affect autoimmunity
- infection
- smoking
- hormone levels
- antigen sequestration
85
What is antigen sequestration?
tissues which do not communicate with blood/lymph. Self antigens normally hidden from the immune system can become exposed and cause immune reaction
86
How can autoimmune diseases be classified?
Pathological (gel & coombs)
| Clinical (organ/non-organ specific)
87
What is grave's disease?
leading cause of hyperthyroidism, auto-antibodies are generated that bind to the thyroid stimulating the hormone receptor
Type 2 hypersensitivity
88
Explain Lupus disease
Type 3 hypersensitivity
Target is nuclear antigens, 90% of cases are female, strong genetic predisposition
Auto-antibodies against nuclear antigens, multi system disease
89
What are the symptoms of lupus?
- vasculitis
- sickness
- nephritis
- alveolitis
90
Describe the pathogenesis of lupus
increased apoptosis, defective clearance of apoptotic material & dysregulation of neutrophil NETs
