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Leila's Yr 5 Pathology > Immunology 1s - Introduction > Flashcards

Immunology 1s - Introduction Flashcards

1
Q

Skin - how does it act as a barrier to infection?

A

Physical barrier: tightly packed keratinised cells
Physiological factors: low pH and low oxygen tension
Sebaceous glands: produce hydrophobic oils and lysozymes

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2
Q

Mucosal surface - 5 ways it acts as a barrier to infection

A

Physical barrier - traps invading pathogens
Mucus contains secretory IgA - binds to pathogens
Lysozyme
Lactoferrin (Starves bacteria of iron)
Cilia

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3
Q

Commensal bacteria - how does it act as a barrier to infection?

A

100tn bacteria, competes with pathogens for resources

Produce fatty acids and bactericides which inhibit pathogen growth

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4
Q

Polymorphonuclear cells include?

A

Neutrophils
Basophils/mast cells
eosinophils

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5
Q

Soluble component of innate immune system

A

Complement
Acute phase proteins
Cytokines/chemokines

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6
Q

How do cells of the innate immune system identify pathogens?

A

PRRs

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7
Q

What receptors do polymorphonuclear cells express?

A

Receptors for cytokines/chemokines to detect inflammation
PRRs
Fc receptors for Ig (Detect immune complexes)

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8
Q

Actions of PMNCs

A

Migrate rapidly to site of injury
Express cytokine/chemokine receptors, Fc for Ig, PRRs
Phagocytosis, oxidative and non-oxidative killing
Release enzymes, histamine, lipid mediators of inflammation from granuels
Release cytokines and chemokines to regulate inflammation

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9
Q

Mononuclear cells include?

A

monocytes, macrophages, lymphocytes

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10
Q

What do monocytes differentiate in to and where does this happen?

A

Differentiate in to macrophages in tissues

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11
Q

How do monocytes differ from PMNCs?

A

They are able to express processed antigen to T cells

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12
Q

Difference between cytokines and chemokines

A

CYtokines –> activate vascular endothelium and enhance vascular permeability
Chemokines –> Attract phagocytes

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13
Q

What do PRRs recognise?

A

PAMPs e.g. bacterial sugars, DNA, RNA

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14
Q

What process is endocytosis facilitated by?

A

Opsonisation

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15
Q

2 ways in which microorganisms are recognised by innate immune response?

A
  1. PRRs e.g. TLRs and mannose receptors

2. Fc receptors for Fc portion of Ig to recognise immune complexes

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16
Q

3 examples of opsonins

A

Antibodies - bind to Fc receptor
APPs (CRP)
Complement (bind to complement receptors

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17
Q

2 killing methods by PMNCs

A

Oxidative killing - NADPH oxidase complex converts oxygen to reactive oxygen species (superoxide and hydrogen peroxide). Myeloperoxidases: production of hydrochlorous acid (an antimicrobial) from hydrogen peroxide and chloride

Non-oxidative killing - Release of lysozyme/lactoferrin from granules into phagolysosome

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18
Q

What happens to neutrophils after they phagocytose a lot?

A

Phagocytosis depletes the glycogen reserves of the neutrophil –> die. As they die, residual enzymes are released which causes liquefaction of adjacent tissue. Accumulation of dead neutrophils in infected tissue –> pus , accumulation of pus –> abscess

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19
Q

What are NK cells?

A

A type of lymphocyte. They are cytotoxic and kill altered-self cells or virus-infected cells

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20
Q

What do NK cells have on their surface which allows them to recognise non-self cells?

A

They have an activating and inhibitory receptor. The inhibitory receptor is for self-HLA molecules to prevent mal-activation by normal self. If inhibitory receptor not activated –> lysis

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21
Q

What do dendritic cells represent?

A

INNATE-ADAPTIVE transformation

22
Q

Following phagocytosis, dendritic cells will…

A

Upregulate expression of HLA molecules
Express co-stimulatory molecules
Migrate via lymphatics to LNs (mediated by CCR7)
Present antigens to T cells in LNs to prime adaptive immune response

23
Q

Soluble components of adaptive immune system

A

Chemokines and cytokines

24
Q

Primary lymphoid organs

A 
bone marrow (T and B cells derived, B cells mature)
Thymus (T cells mature)
25
Q

Adaptive immune system, why is the receptor repertoire not entirely genetically encoded?

A

VDJ recombination means that a vast array of specificities can be generated

26
Q

Secondary lympoid organ examplesq

A

Spleen
MALT
Lymph nodes

27
Q

What process occurs to T cells in the thymus?

A

Positive and negative selection

28
Q

Which CD marker is found on ALL T-cells?

A

CD3

29
Q

Which cells are selected for in the thymus and what % is this?

A

Cells with intermediate affinity ~10% of T-cells

30
Q

What kind of peptides to CD4+ T helper cells recognise?

A

peptides derived from extracellular proteins presented on HLA Class II (HLA DR DP DQ)

31
Q

Which cells have MHC-1 and which have MHC-II?

A

MHC-1 (HLA-A HLA-B HLA-C) - all cells

mHC II - APCs

32
Q

Functions of CD4+ T-helper cells

A

Provide help for developing full B-cell response

Provide help for developing some CD8+ T-cell responses

33
Q

Funciton of CD8+ Cytotoxic killer T-cells?

A

Kill cells directly: perforin and granzymes, expression of Fas ligand
Particularly importnat in defence against viruses and tumours

34
Q

What markers do Tregs express?

A

FOXP3 and CD25

35
Q

What do Th1 cells secret?

A

IFN gamma and IL-2 (subset of CD4 T cell)

36
Q

Which CD4+ T-cell plays an important role in Ig class switching?

A

T follicular helper (Tfh) cells

37
Q

Central toelrance of B cells

A

No recognition of self in BM –> Survive

Recognition of self in BM –> negative selection

38
Q

B cell maturation

A

They originally exist in the periphery as IgM but then can undergo a germinal centre reaction to differentiate in to IgG, igE, IgA

39
Q

Germinal centre reaction

A
  1. Dendritic cell primes CD4+ T cells
  2. cD4+ T helper cell (TFh) help for B cell differentiation (required CD40L:CD40)
  3. B cell proliferation (somatic hypermutation and isotype switching)
40
Q

In which condition is there an absence of CD40L:CD40?

A

Hyper igM syndrome

41
Q

Which part of an immunoglobulin determines its class?

A

Heavy chain

42
Q

Which immunoglobulin predominates the B cell memory response?

A

Response is dominated by IgG antibodies of high affinity (AS opposed to primary response where you get big IgM)

43
Q

What is another difference between primary and secondary B cell response?

A

The memory response may be independent of help from CD4+ T cells

44
Q

What activates the classical complement pathway?

A

Immune complexes. Binding of antigen to antibody results in a conformational change in anitbody shape which exposes binding site for C1. Binding of C1 to immune complex –> activation of cascade.

45
Q

Which complement proteins are involved in the classical pathway?

A

C1,C2,C4

46
Q

Which complement proteins are involved in MBL pathway?

A

C2,C4

47
Q

What activates the MBL pathway?

A

Direct binding of MBL to microbial cell surface carbohydrates. Directly stimulates the classical pathway involving C2 and C4 but NOT C1. NOt dependent on adaptive immune response.

48
Q

What activates the alternative pathway?

A

Direct binding of C3 to bacterial cell wall components e.g. LPS (gram-ve) or teichoic acid (gram+ve).

49
Q

Which factors invovled in alternative complement pathway??

A

BIP

50
Q

Which complement protiens does the final common pathway include?

A

C5-C9 –> MAC (punches holes in bacterial cell walls)

51
Q

Which chemokines are important in dendritic cell homing to LN?

A

CCL19 and CCL21 are important ligands for CCR7 on DCs

Leila's Yr 5 Pathology (100 decks)

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