Innate Immunity Year 2 Flashcards
GIve some examples of pentraxins.
CRP, serum amyloid P (SAP), and PTX3
What is the function of pentraxins?
Soluble pattern recognition molecules that trigger complement activation and/or phagocytosis
CRP activates complement through the classical pathway by binding C1q
Which ligand(s) do pentraxins bind?
Ligands found on bacterial membranes and/or exposed on apoptotic cells
CRP binds microbial phosphorylcholine
SAP binds phosphatidylethanolamine
Give some examples of collectins
MBL and surfactant proteins SP-A and SP-D
What are the two function(s) of MBL?
- Activate complement through the lectin pathway
- Act as an opsonin
What are the four function(s) of SP-A and SP-D?
- Maintain the ability of alveoli to expand by reducing surface tension
- Act as opsonins
- Activate macrophages
- Inhibit bacterial growth
Which ligand(s) does MBL recognize?
Carbohydrates with terminal mannose and fucose
Which ligand(s) do surfactants recognize?
Various microbial structures
What are the two functions of ficolins?
- Opsonize bacteria
- Activate complement in a similar way to MBL
Which ligand(s) do ficolins bind?
N-acetylglucosamine and lipoteichoic acid components of gram positive bacterial cell walls
What are the three functions of complement?
- Opsonize microbes
- Recruit phagocytes to sites of inflammation
- Directly kill microbes
What triggers the classical complement pathway?
Binding of C1q to either pentraxins or the Fc portion of antibodies bound to the surfaces of other microbes
What triggers the alternative complement pathway?
Binding of C3 to microbial surfaces, such as LPS
What triggers the lectin complement pathway?
Binding of MBL to terminal mannose residues on microbial glycoproteins and glycolipids
Which TLRs are located in the plasma membrane?
TLR1, TLR2, TLR4, TLR5, TLR6
Which TLRs are located in endosomes?
TLR3, TLR7, TLR8, TLR9
Which TLR(s) bind gram positive bacteria?
TLR1:TLR2
TLR2
TLR2:TLR6
Which TLR(s) bind gram-negative bacteria?
TLR4
Which TLR(s) bind all flagellated bacteria?
TLR5
Which TLR(s) binds dsRNA?
TLR3
Which TLR(s) binds ssRNA?
TLR7
TLR8
Which TLR(s) binds CpG DNA?
TLR9
Which TLR(s) bind bacterial lipopeptides?
TLR1:TLR2
TLR2:TLR6
Which TLR(s) bind bacterial peptidoglycan?
TLR2
Which TLR(s) bind bacterial flagellin?
TLR5
Which TLR ligand(s) are produced by viruses only?
dsRNA
ssRNA in endosomes
Which TLR ligand(s) are produced by viruses, bacteria and fungi?
CpG DNA
Deficiency in the encoded protein for which gene results in increased susceptibility to herpes simplex encephalitis?
UNC93B1
What is the function of the protein encoded by the UNC93B1 gene?
Trafficking nucleotide sensing toll-like receptors to the endolysosome from the endoplasmic reticulum
What is IRAK4?
A kinase that activates NF-kappaB in both the Toll-like receptor (TLR) and T-cell receptor (TCR) signaling pathways
IRAK4 = interleukin 1 receptor associated kinase 4