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FOM 1 > Week 6 > Flashcards

Week 6 Flashcards

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
Q

In IPEX syndrome what gene shows a mutation?

A

FOXP3

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26
Q

Where is there an immune failure in IPEX?

A

Peripheral tolerance due to absence of regulatory T cells

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27
Q

What type of MHC can be found on all nucleated cells?

A

6 MHC class 1
HLA-1, HLA-2 and HLA-C

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28
Q

What are the genes that code for MHC molecules?

A

Highly polymorphic HLA genes,

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29
Q

What are the class 2 MHC molecules that can be expressed on specialised cells?

A

HLA-DR, HLA-DQ, HLA-DP

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30
Q

What alleles can be associated with increased or decreased risk of autoimmunity development?

A

HLA alleles

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31
Q

What mechanisms can cause environmental factors to trigger autoimmunity?

A

Molecular mimicry
Alterations to self-antigens
Antigen sequestration
Bacterial superantigens

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32
Q

Name some autoimmune conditions driven by type 2 hypersensitivity reactions.

A

Autoimmune haemolytic anaemia
Grave’s disease
Goodpasture’s syndrome
Guillain Barre syndrome
Myasthenia Gravis

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33
Q

What occurs in Goodpasture’s syndrome?

A

Autoreactive antibodies to the alpha3 chain of type 4 collagen present in the basement membranes of alveoli and glomeruli

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34
Q

Name some autoimmune diseases driven by type 3 hypersensitivity reactions.

A

Systemic lupus erythematosus
RA (secondary to type 4)

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35
Q

Name some autoimmune conditions driven by type 4 reactions.

A

Autoimmune myocarditis
T1DM
MS
RA

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36
Q

What is a biofilm?

A

A complex aggregation of microorganisms marked by the excretion of a protective and adhesive matrix

37
Q

What are persistor cells?

A

Metabolically inert cells that exist in a transient state

38
Q

What is an EPS?

A

Extracellular Polymeric Substances, establish the functional and structural integrity of biofilms

39
Q

What is the difference between cross resistance and multiple resistance?

A

Cross resistance - Occurs by single mechanism
Multiple resistance - Occurs by multiple mechanisms

40
Q

What are the 3 methods of horizontal gene transfer?

A

Bacterial transformation
Bacterial transduction
Bacterial conjugation

41
Q

What are the 3 classes of Beta lactamases?

A

Penicillinase
ESBL
Carbapenemase

42
Q

Name the 2 most common Beta-lactamase inhibitors.

A

Clavulanic acid
Tazobactam

43
Q

What does ESBL stand for?

A

Extended Spectrum Beta Lactamase

44
Q

What is the issue with metalloenzyme?

A

Carbapenamase with only one remaining treatment

45
Q

What does SPUR stand for in relation to immunodeficiency?

A

S - Serious infections
P - Persistent infections
U - Unusual infections
R - Recurrent infections

46
Q

What are primary immunodeficiency disorders?

A

Occur due to genetic mutations

47
Q

When do primary immunodeficiency disorders present?

A

Infancy and early childhood

48
Q

What leads to a humoral immunity deficiency?

A

B cell defects, reduced number of or absent/reduced Ig levels

49
Q
A
50
Q

What is the pathogenesis of a humoral immunity deficiency?

A

Block in B cell development or defective CD4+ Tfh cells

51
Q

What is the pathogenesis of XLA?

A

Block in differentitation and development of pre B cells

52
Q

Where does the mutation occur in XLA?

A

BTK gene

53
Q

How is XLA treated?

A

IVIG

54
Q

What is the pathogenesis of HIGM syndrome?

A

Defective interactions between B cells and Tfh cells

55
Q

What are the immunological features of HIGM syndrome?

A

Normal B lymphocyte numbers
Normal/elevated IgM
Decreased IgG

56
Q

Where is the most common mutation leading to HIGM?

A

CD40L gene

57
Q

What is CD40L important as?

A

Important co-stimulatory molecule found on Tfh cells.

58
Q

What is the pathogenesis of T cell mediated immunodeficiencies?

A

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
Q

What occurs in DiGeorge syndrome?

A

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
Q

What are the immunological features of combined immunodeficiencies?

A

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
Q

What is X-SCID?

A

X-linked Severe Combined Immunodeficiency
Failure of T cell and NK cell development
Usually B cells present but little Ig production

62
Q

What occurs in phagocytic deficiencies?

A

Phagocytic cells are impaired cutaneous staphylococcal and gram -ve are characteristic

63
Q

What are the most common phagocytic deficiencies?

A

Chronic granulomatous disease
Leukocyte adhesion deficiency
Chediak-Higashi syndrome

64
Q

What is the pathogenesis of chronic granulomatous disease?

A

Defect in generation of oxidative radicals needed by phagocytic cells
Can’t assemble NADPH complex

65
Q

Name some common secondary immune deficiency conditions?

A

HIV
Measles
Anti-cancer therapy
Immunosuppressive therapy
Cancers of the immune systems
T1 and T2DM

66
Q

What cells does HIV infect?

A

CD4+ T cells, macrophages and dendritic cells

67
Q

What is the cell surface protein that the absence of has been known to “cure” HIV?

A

CCR5

68
Q

What is the function of the epithelial barrier in the GI tract?

A

Physical barrier
Secretory function
Selectively permeable

69
Q

What cell type are found in the base of the crypt in the GI epithelial barrier?

A

Lgr5+ stem cells

70
Q

Where are immune cells found in the GI tract?

A

Lamina propria

71
Q

Name the specialised immune cells found only in the GI tract.

A

Intra-epithelial T cells

72
Q

How do immune cells impact intestinal epithelial cells?

A

Promote barrier repair
Promote mucin production
Macrophage and Treg derived mediators - Stimulate repair
Impact on permeability

73
Q

Where are M cells found?

A

In the GALT of the Peyer’s patches of the small intestine

74
Q

How are antigens brought across the GI epithelial barrier?

A

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
Q

What are the 3 signals that determine T cell response?

A

MCH/Peptide-TCR
CD80-CD28
Cytokine

76
Q

What on the endothelium do gut-homing effector T cells bind to?

A

MAdCAM-1

77
Q

What are intraepithelial lymphocytes?

A

CD8+ T cells found in the epithelial lining of the gut

78
Q

What immunoglobulin is important in the gut mucosa?

A

IgA

79
Q

What are the 3 classifications for appropriate antibiotic prescribing?

A

Access
Watch
Reserve

80
Q

What areas of the GI tract tend to be densely populated by microorganisms?

A

Colon
Ileum

81
Q

What areas of the GI tract tend to be sparsely populated?

A

Duodenum
Stomach
Jejunum

82
Q

Name 2 common viral diseases of the GI tract?

A

Norovirus
Rotavirus

83
Q

What are the 3 most common prokaryotic infections of the GI tract?

A

E.Coli
Campylobacter
C.Diff

84
Q

Name some common E.Coli variants?

A

Enteropathogenic
Enterotoxigenic
Shiga toxin-producing
Enteroinvasive

85
Q

What symptoms are experienced in E.coli 0157?

A

Diarrhoea
Haemorrhagic colitis
Abdominal cramps
Little to no fever

86
Q

Is E.coli 0157 a Shiga toxin bacteria?

A

Yes

87
Q

What is first line treatment for C.Diff?

A

Vancomycin
Stop predisposing antibiotic treatment

88
Q
A

FOM 1 (14 decks)

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