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Year 5 path SW COPY > Immuno 1: Immune Response To Infection/primary Immune Deficiencies 1 > Flashcards

Immuno 1: Immune Response To Infection/primary Immune Deficiencies 1 Flashcards

1
Q

List 4 ways in which the skin is able to act as a barrier to infection ?

A

tightly packed keratinised cells
Low PH
Low oxygen tension
Sebaceous glands- hydrophobic oils, lysosymes, ammonia, defensins

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2
Q

List 4 ways in which the mucous membrane acts as a barrier to infection ?

A

Secretory IgA in the mucous- prevents bacteria from attaching and penetrating

Lysosymes
Lactoferrin- starves bacteria of iron
Cilia- actively traps and removes bacteria

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3
Q

Which receptors allow cells of the innate immune system to recognise pathogens ?

A

PRRs - pattern recognition receptors

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4
Q

List 3 polymorphonuclear cells ?

A

Neutrophils
Eosinophils
Basophils

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5
Q

How do Neutrophils detect immune complexes ?

A

They have Fc receptors for the Immunoglobulin (antibody) in the complex

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6
Q

Give one example of how neutrophils and Macrophages differ in function ?

A

Macrophages can also phagocytose pathogens but they are able to process the antigen and present the antigen to T cells

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7
Q

Give 2 examples of PRRs ?

A

Toll like receptors

Mannose receptors

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8
Q

Give 3 examples of opsonins ?

A

Antibodies
Complement
Acute phase proteins - CRP

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9
Q

Give 2 examples of enzymes involved in oxidative killing of pathogens ?

A

NADPH oxidase - converts oxygen into reactive oxygen species

Myeloperoxidase- catalysts the production of HCL acid

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10
Q

Give 2 examples of enzymes involved in non-oxidative killing of pathogens ?

A

Lactoferrin

Lysozyme

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11
Q

What is pus ?

A

Collection of dead and dying neutrophils in infected tissues

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12
Q

Which inhibitory receptors stop NK cells from destroying self cells ?

A

HLA receptors

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13
Q

Which activating receptor causes NK cells to become cytotoxic ?

A

Heparan sulphate receptors

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14
Q

Which chemokine receptor mediates the migration of dendritic cells into the lymphatics to lymph nodes ?

A

CCR7

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15
Q

What is the role of Dendritic cells ?

A

They reside in peripheral tissue and can phagocytose pathogens.
They then migrate into the lymphatics and present the processed antigen to T cells to prime the Adaptive immune system.

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16
Q

Where does lymph re enter the circulation ?

A

Thoracic duct

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17
Q

How do NK cells recognise infected cells ?

A

The infected cell (e.g dendritic cell )will down-regulate inhibitory molecules such as HLA and up-regulate activatory molecules such as modified pathogen antigen.

The NK cell can now recognise the cell as altered cell and starts cytotoxic killing

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18
Q

List 2 organs that are considered primary lymphoid organs ?

A

Bone marrow

Thymus

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19
Q

Where does T cell maturation occur ?

A

Thymus

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20
Q

Where do B cells undergo affinity maturation and isotope switching ?

A

Germinal centres

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21
Q

Give 3 examples of secondary lymphoid organs ?

A

Lymph nodes
Spleen
MALT- mucosal associated lymphoid tissue

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22
Q

What does the TCR do ?

A

Recognises peptide presented by the target or antigen presenting cell (APC)

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23
Q

Which T cells recognise peptide presented by HLA Class 1 ?

A

CD8+ T cells

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24
Q

Which T cells recognise peptide presented by HLA Class 2 ?

A

CD4+ T cells

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25
Q

Which T cells are thought to be associated with Autoimmune disease ?

A

Th17 T cells

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26
Q

Give 2 ways in which CD8+ T cells cause cytotoxic killing of cells infected by intracellular pathogens e.g viruses

A

Perforin (forms a pore into cell ) and granzyme

Express Fas Ligands

27
Q

Which T cells express Foxp3 and CD25 ?

A

T reg cells

28
Q

Which T cell helps in B cell maturation ?

A

Tfh cells (follicular helper)

29
Q

What is somatic hypermutation ?

A

The variable region of the B cell antibodies / receptor are edited

30
Q

What are the 3 pathways of complement activation ?

A

Classical
Alternative
MBL- mannose binding leptin

31
Q

How is the classical complement pathway activated ?

A

Immune complexes

32
Q

How is the MBL complement pathway activated ?

A

MBL binds to a microbial carbohydrate such as mannose

33
Q

How is the alternative complement pathway activated ?

A

Bacterial cell walls components bind directly to C3z

34
Q

What triggers the formation of the MAC (membrane attack complex) ?

A

activation of C3 convertase (common pathway of all 3 complement pathways)

35
Q

how do commensal bacteria inhibit growth of pathogens

A

compete with pathogenic bacteria for scarce resources

produce fatty acids and bactericidins that inhibit growth of pathogens

36
Q

list cells of the immune system

A

PMN cells
monocytes and macrophages
NK cells
dendritic cells

37
Q

list soluble components of the immune system

A

cmplement
APP
cytokines and chemokines

38
Q

what are the roles of PMN cells

A

express receptors for cytkines/ chemokines to detect inflammation
express PRR - to detect pathogens
express Fc receptors for Ig - to detect immune complexes
capable of phagocytosis + oxidative/ non oxidative killing
release enzymes, histamine, lipid mediators of inflammation from granules
secrete cytokines and chemokines to regulate inflammation

39
Q

what are the roles of cytokines and chemokines in phagocytes recruitment

A

cytokines - activate vascular endothelium enhancing permeability
chemokines - attract phagocytes

40
Q

how are microorganisms recognised by phagocytes

A

PPRs like TLLs and mannose receptors recognise generic motifs known as PAMPs
Fc receptors on these cells allows them to bind to the Fc portion of immunoglobulins allowing phagocytes to recognise immune complexes

41
Q

what is the role of opsonins in phagocytosis

A

forms a bridge between the pathogen and the phagocytes receptors
complement components can bind complement receptors
APPs also promote phagocytosis

42
Q

how is a phagolysosome formed

A

pathogen taken up into a phagosome
fuses with a lysosome
killing of the pathogen via oxidative and non-oxidative methods

43
Q

how do phagocytes die

A

phagocytosis depleats glycogen reserves in the neurtophil
causes neutrophil death
accumulation –> pus

44
Q

how do NK cells work

A

express inhibitory receptors for self HLA

express activating receptors including those that recognise heparan sulphate proteoglycans

45
Q

what are the roles of dendritic cells

A 
reside in peripheral tissues 
express PRRs
express Fc receptors 
capable of phagocytosis
following phagocytosis, densritic cells:
- upregulate expression of HLA molecules
express co-stimulatory molecules
migrate via lymphatics to LN (mediated by CCR7)
46
Q

how are microorganisms recognised by phagocytes

A

PPRs like TLLs and mannose receptors recognise generic motifs known as PAMPs
Fc receptors on these cells allows them to bind to the Fc portion of immunoglobulins allowing phagocytes to recognise immune complexes

47
Q

what is the role of opsonins in phagocytosis

A

forms a bridge between the pathogen and the phagocytes receptors
complement components can bind complement receptors
APPs also promote phagocytosis

48
Q

how is a phagolysosome formed

A

pathogen taken up into a phagosome
fuses with a lysosome
killing of the pathogen via oxidative and non-oxidative methods

49
Q

how do phagocytes die

A

phagocytosis depleats glycogen reserves in the neurtophil
causes neutrophil death
accumulation –> pus

50
Q

how do NK cells work

A

express inhibitory receptors for self HLA

express activating receptors including those that recognise heparan sulphate proteoglycans

51
Q

what are the roles of dendritic cells

A 
reside in peripheral tissues 
express PRRs
express Fc receptors 
capable of phagocytosis
following phagocytosis, densritic cells:
- upregulate expression of HLA molecules
express co-stimulatory molecules
migrate via lymphatics to LN (mediated by CCR7)
52
Q

what are the components of the adaptive immune system

A

humoral immunity - B lymphocytes and antibodies
cellular immunity - T lymphocytes
soluble components - cytokines and chemokines

53
Q

list the functions of antibodies

A

identification of pathogens and toxins (Fab mediated)
interact with other components of immune respones to remove pathogens (Fc mediated)
especially involved in defence against bacteria

54
Q

describe T lymphocyte maturation

A 
CD4+ recognises peptides presented by HLA class II
CD8+ recognises peptides presented by HLA class I
intermediate affinity = positively selected
55
Q

features of CD4+ (T helper cells)

A

recognise peptides derived from extracellular protiens
peptides presented on HLA class II molecules (HLA-DR - DP, DQ)
help for the development of a full B cell response
provide help for development on some CD8+ responses

56
Q

list subsets of CD4 T cells

A 
Th 1 - helps CD8+ T cells and macrophages 
Th17 - helps neutrophil recruitment 
T reg - IL-10/TGF beta expressing 
TFh - follicular helper 
Th2 - helper
57
Q

features of CD8+ cytotoxic T cells

A

recognise peptides derived from intracellular proteins presented on HLA class I (HLA A-B-C-)
kills cells directly - perforin and granzymes, expression of fas ligand
secrete cytokines
important against viral infections and tumours

58
Q

descibe what happens when B cells encounter an antigen

A

early IgM response -differentiates into an IgM secreting plasma cell
In germinal centre:
- dendritic cells prime CD4+ T helper
- CD4+ cells provide help for B cell differentiation
- mediated by CD40L:CD40
- with help of CD4+ cells, B cells proliferate
- undergo somatic hypermutation and isotope switching (from IgM to IgG/A/E)

59
Q

difference with B memory cells

A

lag time between antigen exposure and antibody production is decreased
titres of antibody produced is increased
response dominated by IgG antibodies of high affinity

60
Q

what is complement

A

20+ tightly regulated, linked proteins
made by liver
in circulation as inactivated molecules
when triggered, they activate a biological cascade

61
Q

what are the 3 pathways in complement activation

A

classical (C1,2,4): activated by immune complexes, forming antigen antibody complexes causes a conformational change - exposes the binding site for C1) - activates the cascade

mbl (C2,4): activated by direct binding of MBL to microbial cell surface carbohydrates, directly stimulates the classical pathway involving C2+ 4 NOT 1)
not dependent on adaptive immune response

alternative: directly triggered by binding of C3 to bacterial cell wall components
not dependent on adaptive response
involves factors: BIP

(final common pathway C5-9 –> MEMBRANE ATTACK COMPLEX)

62
Q

what are the roles of complement

A 
increase vascular permeability 
opsonisation of immune complexes
opsonisation of pathogens 
activation of phagocytes 
promotes mast cell/ basophil degranulation 
punches holes in bacterial membranes
63
Q

cytokines vs chemokines

A

cytokines = small protein messengers
immunomodulatory function
autocrine and paracrine dependent action
eg IL2,6,10,12,TNF a, TGF b

chemokines = subset of cytokines
direct recruitment/homing of leukocytes in an inflammatory response
CCL19 + CCL21 are ligands for CCR7 and important in directing dendritic cell trafficking to lymph nodes

Year 5 path SW COPY (106 decks)

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