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FOM 1 > Week 6 > Flashcards

Week 6 Flashcards

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1
Q

How are hypersensitivity reactions classified?

A

Gel and Coomb’s classification
Types 1 to 4

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2
Q

What type of hypersensitivity reaction is linked to allergy?

A

Type 1

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3
Q

What cell types are involved in allergic reactions and what Ig type?

A

Mast cells
B cells
TH2 cells
Eosinophils
IgE

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4
Q

What outcomes can there be from Th2 development?

A

Differentiation to Th1 and no allergies
Remain Th2 and allergies, asthma present

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5
Q

When an allergen is re-encountered by the immune system what occurs?

A

Binds to IgE coated mast cells and basophils leading to degranulation
Vasoactive mediators are released
Increased expression of pro-inflammatory cytokines and leukotrienes
Recruitment and activation of eosinophils

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6
Q

What antibodies mediate type 2 hypersensitivity reactions?

A

IgM/IgG

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7
Q

What is the difference between a type 2a and type 2b hypersensitivity reaction?

A

Type 2a - Destruction of antigen-positive cells
Type 2b - Stimulation of cell surface antigens

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8
Q

Describe type 3 hypersensitivity reactions.

A

Results from soluble antigen-antibody immune complexes passing between endothelial blood vessel cells and becoming trapped on the surrounding basement membrane leading to inflammation

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9
Q

Give some examples of type 3 hypersensitivity reactions.

A

Acute hypersensitivity pneumonitis
E.g. Farmer’s lung
Bird fancier’s lung

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10
Q

What T cell type drive type 4 hypersensitivity?

A

CD4+ T cells

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11
Q

What are the classic hallmarks of a type 4 hypersensitivity reaction?

A

Large number of macrophages at the reaction site
Takes an average of 24-48 hours for symptoms to manifest after re-exposure to the initiating antigen
Granulomas often form due to infectious pathogens/ foreign bodies that cannot be cleared

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12
Q

What occurs in a type 4 hypersensitivity reaction?

A

CD4+ T cells are activated by an antigen, proliferation and differentiation of effector Th1 cells leading to macrophage recruitment and activation.

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13
Q

What chromosome is the heavy chain locus found?

A

Chromosome 14

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14
Q

What chromosomes can the light chain locus be found on?

A

Chromosome 2 kappa locus
Chromosome 22 lambda locus

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15
Q

What are the 4 regions on the heavy chain of an Ig?

A

Variable region
Diversity region
Joining region
Constant region

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16
Q

What does the C region of an antibody determine?

A

The antibody class

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17
Q

What do the V, D and J regions of an antibody form?

A

Specific antigen binding site

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18
Q

What purpose does random recombination of V, D and J gene segments serve?

A

Gives each B cell its own unique antibody

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19
Q

How many antigen binding sites are present in an antibody molecule?

A

2

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20
Q

How does the immune system deal with autoreactive T and B cells?

A

Central tolerance - Deletion in primary lymphoid tissues.
Peripheral tolerance - Regulatory T cells can help inactivate in peripheral tissues.

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21
Q

What is the function of regulatory T cells?

A

Inactivation of lymphocytes

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22
Q

How do regulatory T cells suppress hyper-active or auto-reactive T cells?

A

Anti-inflammatory cytokines

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23
Q

What are the symptoms of IPEX syndrome?

A

Severe infections
Intractable diarrhoea
Eczema
Very early onset insulin dependent diabetes
Autoimmune manifestations

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24
Q

What is the treatment for IPEX syndrome?

A

Hematopoietic stem cell transplant

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25
In IPEX syndrome what gene shows a mutation?
FOXP3
26
Where is there an immune failure in IPEX?
Peripheral tolerance due to absence of regulatory T cells
27
What type of MHC can be found on all nucleated cells?
6 MHC class 1 HLA-1, HLA-2 and HLA-C
28
What are the genes that code for MHC molecules?
Highly polymorphic HLA genes,
29
What are the class 2 MHC molecules that can be expressed on specialised cells?
HLA-DR, HLA-DQ, HLA-DP
30
What alleles can be associated with increased or decreased risk of autoimmunity development?
HLA alleles
31
What mechanisms can cause environmental factors to trigger autoimmunity?
Molecular mimicry Alterations to self-antigens Antigen sequestration Bacterial superantigens
32
Name some autoimmune conditions driven by type 2 hypersensitivity reactions.
Autoimmune haemolytic anaemia Grave's disease Goodpasture's syndrome Guillain Barre syndrome Myasthenia Gravis
33
What occurs in Goodpasture's syndrome?
Autoreactive antibodies to the alpha3 chain of type 4 collagen present in the basement membranes of alveoli and glomeruli
34
Name some autoimmune diseases driven by type 3 hypersensitivity reactions.
Systemic lupus erythematosus RA (secondary to type 4)
35
Name some autoimmune conditions driven by type 4 reactions.
Autoimmune myocarditis T1DM MS RA
36
What is a biofilm?
A complex aggregation of microorganisms marked by the excretion of a protective and adhesive matrix
37
What are persistor cells?
Metabolically inert cells that exist in a transient state
38
What is an EPS?
Extracellular Polymeric Substances, establish the functional and structural integrity of biofilms
39
What is the difference between cross resistance and multiple resistance?
Cross resistance - Occurs by single mechanism Multiple resistance - Occurs by multiple mechanisms
40
What are the 3 methods of horizontal gene transfer?
Bacterial transformation Bacterial transduction Bacterial conjugation
41
What are the 3 classes of Beta lactamases?
Penicillinase ESBL Carbapenemase
42
Name the 2 most common Beta-lactamase inhibitors.
Clavulanic acid Tazobactam
43
What does ESBL stand for?
Extended Spectrum Beta Lactamase
44
What is the issue with metalloenzyme?
Carbapenamase with only one remaining treatment
45
What does SPUR stand for in relation to immunodeficiency?
S - Serious infections P - Persistent infections U - Unusual infections R - Recurrent infections
46
What are primary immunodeficiency disorders?
Occur due to genetic mutations
47
When do primary immunodeficiency disorders present?
Infancy and early childhood
48
What leads to a humoral immunity deficiency?
B cell defects, reduced number of or absent/reduced Ig levels
49
50
What is the pathogenesis of a humoral immunity deficiency?
Block in B cell development or defective CD4+ Tfh cells
51
What is the pathogenesis of XLA?
Block in differentitation and development of pre B cells
52
Where does the mutation occur in XLA?
BTK gene
53
How is XLA treated?
IVIG
54
What is the pathogenesis of HIGM syndrome?
Defective interactions between B cells and Tfh cells
55
What are the immunological features of HIGM syndrome?
Normal B lymphocyte numbers Normal/elevated IgM Decreased IgG
56
Where is the most common mutation leading to HIGM?
CD40L gene
57
What is CD40L important as?
Important co-stimulatory molecule found on Tfh cells.
58
What is the pathogenesis of T cell mediated immunodeficiencies?
Developmental problem affecting thymus development Block in T cell development and differentiation Ig deficiencies often present due to lack of B cell/T cell interactions
59
What occurs in DiGeorge syndrome?
Developmental defect causing aplasia or hypoplasia of thymus and parathyroid glands, facial defects and congenital heart defects. Immune defects may be partial (some T cell function) or complete (Absent T cell function)
60
What are the immunological features of combined immunodeficiencies?
Decreased lymphocytes No thymus development or underdevelopment Small number of T cells that fail to respond to antigens Variable effect on B cells/NK cells and T cells depending on mutation
61
What is X-SCID?
X-linked Severe Combined Immunodeficiency Failure of T cell and NK cell development Usually B cells present but little Ig production
62
What occurs in phagocytic deficiencies?
Phagocytic cells are impaired cutaneous staphylococcal and gram -ve are characteristic
63
What are the most common phagocytic deficiencies?
Chronic granulomatous disease Leukocyte adhesion deficiency Chediak-Higashi syndrome
64
What is the pathogenesis of chronic granulomatous disease?
Defect in generation of oxidative radicals needed by phagocytic cells Can't assemble NADPH complex
65
Name some common secondary immune deficiency conditions?
HIV Measles Anti-cancer therapy Immunosuppressive therapy Cancers of the immune systems T1 and T2DM
66
What cells does HIV infect?
CD4+ T cells, macrophages and dendritic cells
67
What is the cell surface protein that the absence of has been known to "cure" HIV?
CCR5
68
What is the function of the epithelial barrier in the GI tract?
Physical barrier Secretory function Selectively permeable
69
What cell type are found in the base of the crypt in the GI epithelial barrier?
Lgr5+ stem cells
70
Where are immune cells found in the GI tract?
Lamina propria
71
Name the specialised immune cells found only in the GI tract.
Intra-epithelial T cells
72
How do immune cells impact intestinal epithelial cells?
Promote barrier repair Promote mucin production Macrophage and Treg derived mediators - Stimulate repair Impact on permeability
73
Where are M cells found?
In the GALT of the Peyer's patches of the small intestine
74
How are antigens brought across the GI epithelial barrier?
M cells take up the antigen by endocytosis and phagocytosis and transport it across to be bound by dendritic cells Dendritic cells can also extend across the epithelial layer to capture antigens from the lumen
75
What are the 3 signals that determine T cell response?
MCH/Peptide-TCR CD80-CD28 Cytokine
76
What on the endothelium do gut-homing effector T cells bind to?
MAdCAM-1
77
What are intraepithelial lymphocytes?
CD8+ T cells found in the epithelial lining of the gut
78
What immunoglobulin is important in the gut mucosa?
IgA
79
What are the 3 classifications for appropriate antibiotic prescribing?
Access Watch Reserve
80
What areas of the GI tract tend to be densely populated by microorganisms?
Colon Ileum
81
What areas of the GI tract tend to be sparsely populated?
Duodenum Stomach Jejunum
82
Name 2 common viral diseases of the GI tract?
Norovirus Rotavirus
83
What are the 3 most common prokaryotic infections of the GI tract?
E.Coli Campylobacter C.Diff
84
Name some common E.Coli variants?
Enteropathogenic Enterotoxigenic Shiga toxin-producing Enteroinvasive
85
What symptoms are experienced in E.coli 0157?
Diarrhoea Haemorrhagic colitis Abdominal cramps Little to no fever
86
Is E.coli 0157 a Shiga toxin bacteria?
Yes
87
What is first line treatment for C.Diff?
Vancomycin Stop predisposing antibiotic treatment
88

FOM 1 (14 decks)

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