Innate

Question 1

Antimicrobial proteins

Answer 1

▪️lysozyme
-enzyme attack bacterial cell walls 
▪️defensins, cathelicidins 
-disrupt membrane 
▪️c-type lectins 
-RegIIIy

Question 2

APP

Answer 2

▪️produced in liver in response to inflammatory
▪️recruit ICs
▪️pattern recognition and activation of CS
▪️bind and kill pathogen
▪️opsonisation-enhance phagocytosis
▪️ex complement proteins, collectins

Question 3

Collectins

Answer 3

▪️APP
▪️soluble PRR 
▪️bind to PAMPs on microbes 
▪️opsonisation, stimulation of phagocytosis and CS
▪️eg mannose binding lectin

Question 4

Complement system activation

Answer 4

▪️detection and destruction of pathogens
▪️activation: recognition of the surface of microbe
-classical- antibody
-alternative- direct contact
-lectin- carbohydrate binding mediators

Question 5

Classical pathway

Answer 5

▪️IgG molecules bind to antigen on pathogen
▪️C1q binds to two or more IgG molecules
▪️initiates generation of C3 convertase

Question 6

Alternate pathway

Answer 6

▪️C3 undergoes spontaneous hydrolysis

▪️initiates deposition of C3 convertase on microbial surfaces

Question 7

Lectin pathway

Answer 7

▪️different lectins bind to specific molecules on microbial surfaces
▪️lead to generation of C3 convertase

Question 8

Cleavage of C3

Answer 8

▪️C3 convertase cleaves C3 into C3a and C3b
▪️C3a-increases vasodilation and vascular permeability and recruits ICs
▪️C3b- opsonisation

Question 9

C5 and the membrane attack complex

Answer 9

▪️C5T convertase cleaves C5 into C5a and C5b
▪️C5a- increases vascular permeability
▪️C5b together with C6,7,8,9 form a membrane attack complex which binds to pathogen surface to create a pore- free diffusion of molecules causing it to die

Question 10

PRR families

Answer 10

▪️toll like receptors
-on plasma membrane 
-responds to DNA, RNA, peptidoglycan, PAMPs from B,V,P and self 
▪️NOD like receptors 
-cytoplasm 
-responds to DAMPs
-self and B

Question 11

Triggering TLR4 on dendritic cells

Answer 11

▪️dendritic cells recognise bacteria surface through TLR4 leading to:
-production of pro-inflammatory cytokines
-up-regulation of molecules needed for T cell activation
-up-regulation of class II MHC
▪️enhance adaptive immune response

Question 12

NK cells

Answer 12

▪️bone marrow lymphocytes
▪️10% of peripheral lymphocytes
▪️granulated
▪️protection from viral infection and cancers
▪️produce pro-inflammatory cytokines which enhance AIS
▪️kill virus infected and tumour cells
▪️kills cells lacking class I MHC

Question 13

NK killing mechanism

Answer 13

▪️viruses-infected and tumour cells down regulates class I MHC to avoid T cells
▪️NK cell inhibitory receptors recognise class I MHC, if cell does not have it, NK is activated
▪️secrete perforin and granzymes
▪️perforin create pores and granzymes enter to induce apoptosis