Lecture 5 and 6: Microbial Recognition and Signal Transduction

Question 1

What protects the skin and membranes?

Answer 1

• Acidic pH
• Commensals
• Enzymes
• Mucous
• IgA

Question 2

What are the natural antibiotics?

Answer 2

Restriction Factors - block viral establishments
Interferons - released at the site of viral entry
Lysozyme - lytic enzyme made by macrophages
Defensin - antibacterial peptide made at mucosal surfaces

Question 3

Microbial success depends on…….

Answer 3

• The ability to evade, inhibit or resist the immune response
• Persist in the host
• The ability to leave the body and spread

Question 4

The C’ and phagocytic response occur within _________ of infection

Answer 4

minutes

Question 5

C3 + antibody ________________ to phagocytic cells via ___ and ___ receptors. This is called ___________.

Answer 5

enhance attachment
Fc and C3 receptors
Opsonisation

Question 6

When inside the cell, microbes are killed and degraded by _________________ and _____________.

Answer 6

Reactive oxygen species

Lysosomal enzymes

Question 7

Helper T cells respond to __________________ and stimulate _________ synthesis. They also secrete ________ to help attract and stimulate _________.

Answer 7

presented antigen
Antigen
Cytokines
CD8s and macrophages/eosinophils

Question 8

NK cells kill _____________ in a non-specific way and are activated by the __________________________.

Answer 8

virally infected

loss of host cell MHC1

Question 9

What is sequestration?

Answer 9

When a microbe can’t be eliminated it is walled off by macrophages and fibroblast to form a granuloma

Question 10

What are the soluble recognition molecules?

Answer 10

C’ - get triggered by contact with bacteria
Mannose-Binding Lectin - activate C’ or phagocytosis
Acute Phase Proteins - contribute to recognition and some are PRRs

Question 11

What is a PRR?

Answer 11

A Pattern Recognition Receptor that recognises highly conserved features of microbes called PAMPs

Question 12

What is a PAMP?

Answer 12

A Pathogen Associated Molecular Pattern, highly conserved feature of a microbe i.e. LPS (Lipopolysaccharide)

Question 13

TcRs recognise ___________ bound to ______

Answer 13

Small peptide bound to MHC

Question 14

How are NK cells activated?

Answer 14

2 signals:
Activating receptors - analogous to PPRs and recognise changes associated with stress and viral infection
Inhibiting receptors - recognise MHC1 and prevent the NK cells from killing

Question 15

What is a DAMP?

Answer 15

Damage Associated Molecular Pattern activates some innate PRRs in the absence of infection

Question 16

What are the Dectin-1 and Mannose receptors and what do they do?

Answer 16

Sugar binding proteins that recognise the CHOs of the walls of bacteria and fungi and cause phagocytosis

Question 17

Describe the structure of a Toll-Like Receptor (TLR)?

Answer 17

A horseshoe shaped transmembrane protein that has an intracytoplasmic TIR region which associates with adapter molecules

Question 18

What do TLRs do?

Answer 18

Used to differentiate between self and non-self antigens and activate the release of chemical messengers as soon as they are activated by a PAMP

Question 19

TLR4 recognises _________________

Answer 19

Lipopolysaccharide (LPS)

Question 20

What does NFkB control?

Answer 20

Regulation of genes involved in:

• Innate immunity
• Inflammation
• Stress responses
• B cell development
• Lymphoid organogenesis

Question 21

Where are TLRs located?

Answer 21

On the cell membrane and on endosomal membranes

Question 22

What is an inflammasome?

Answer 22

Multimolecular complex found in the cytoplasm of macrophages and some epithelial cells that is assembled in response to NOD-like receptors (NLRs) that leads to the secretion of pro-inflammatory cytokines IL-1 and IL-8