Lecture 5 and 6: Microbial Recognition and Signal Transduction Flashcards
What protects the skin and membranes?
- Acidic pH
- Commensals
- Enzymes
- Mucous
- IgA
What are the natural antibiotics?
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
Microbial success depends on…….
- The ability to evade, inhibit or resist the immune response
- Persist in the host
- The ability to leave the body and spread
The C’ and phagocytic response occur within _________ of infection
minutes
C3 + antibody ________________ to phagocytic cells via ___ and ___ receptors. This is called ___________.
enhance attachment
Fc and C3 receptors
Opsonisation
When inside the cell, microbes are killed and degraded by _________________ and _____________.
Reactive oxygen species
Lysosomal enzymes
Helper T cells respond to __________________ and stimulate _________ synthesis. They also secrete ________ to help attract and stimulate _________.
presented antigen
Antigen
Cytokines
CD8s and macrophages/eosinophils
NK cells kill _____________ in a non-specific way and are activated by the __________________________.
virally infected
loss of host cell MHC1
What is sequestration?
When a microbe can’t be eliminated it is walled off by macrophages and fibroblast to form a granuloma
What are the soluble recognition molecules?
C’ - get triggered by contact with bacteria
Mannose-Binding Lectin - activate C’ or phagocytosis
Acute Phase Proteins - contribute to recognition and some are PRRs
What is a PRR?
A Pattern Recognition Receptor that recognises highly conserved features of microbes called PAMPs
What is a PAMP?
A Pathogen Associated Molecular Pattern, highly conserved feature of a microbe i.e. LPS (Lipopolysaccharide)
TcRs recognise ___________ bound to ______
Small peptide bound to MHC
How are NK cells activated?
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
What is a DAMP?
Damage Associated Molecular Pattern activates some innate PRRs in the absence of infection
What are the Dectin-1 and Mannose receptors and what do they do?
Sugar binding proteins that recognise the CHOs of the walls of bacteria and fungi and cause phagocytosis
Describe the structure of a Toll-Like Receptor (TLR)?
A horseshoe shaped transmembrane protein that has an intracytoplasmic TIR region which associates with adapter molecules
What do TLRs do?
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
TLR4 recognises _________________
Lipopolysaccharide (LPS)
What does NFkB control?
Regulation of genes involved in:
- Innate immunity
- Inflammation
- Stress responses
- B cell development
- Lymphoid organogenesis
Where are TLRs located?
On the cell membrane and on endosomal membranes
What is an inflammasome?
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
