L1.3 Specific/adaptive immunity

Question 1

What are dendritic cells

Answer 1

• Are Antigen presenting cells (APC)
• Senses/engulfs external particles → display foreign antigens on surface

Question 2

What are lymphocytes

Answer 2

• T-cells
  
  • Helpers (CD4+) cytokines
  • Cytotoxic (CD8+)
• B-cells → creates AB

Question 3

Features of asthma

Answer 3

• caused by sustained mucosal infections in the lungs
• Tissue damage & altered
• Mechanism:
  
  • Dendritic cells pick up allergens → T2 cells → B cells (which produces IgE - only in asthma) & cytokines → both stimulating inflammatory cells (mast/eosinophils)
    
    • Causes tissues damage/S.M damage/attenuates repair
    • IgG is normally made in place of IgE

Question 4

What is the normal non-asthmatic immune response?

Answer 4

• Foreign material in airway → inflammation recruits neutrophils & lymphocytes; dendritic cells activated → leaves tissues into lymph node
• Dendritic cells presents antigens to T-cells (MHC 1 & 2) → Co-stimulates IL-2 and allows proliferation of T-cells
  
  • Dendritic cells recycled back to tissues
• T-cells help B-cells produce antibody → bind & neutralise antigen

Question 5

What is the role of AB

Answer 5

• Neutralization of toxins
• Activation of complement: kill/ingest
• Opsonisation for macrophages
  
  • (identify foreign particles for macrophages)
• B cell antigen recognition system
• Persistent protection (usually)

Question 6

What is the mechanism of dendritic cells in lymph nodes

Answer 6

• Capture foreign antigen & present on MHC surface → to T cell R. CD4/8 (which is randomly generated)
  
  • T-cells determine magnitude of response
  • As T-cells are randomly generated, they circulate in tight lymph node env to find correct match for presented antigen

Question 7

T-cell R (Th1 & 2)

Answer 7

• Th1 → for bacteria
  
  • Goes wrong → Multiple sclerosis; Rheumatoid arthritis
• Th2 → Parasites
  
  • Goes wrong → asthma

Question 8

How do diseases become chronic? (e.g. asthma)

Answer 8

• Innate starts asthma → Th2 pathway (for first few years of childhood) → ILC 2 expands
  
  • ILC 2 don’t require normal activation - having innate properties
    
    • Activated by PRR & [ILC2] usually low
• With ↑[ILC2] → simple tissue damage (i.e. inflammation…) releases cytokine activating factors (same as Th2 cells)
• Innate response now primes disease → becomes chronic

Question 9

CD8 cells

Answer 9

• CD8 cells have perforins & granzymes

1. Perforin punch holes in
2. Granzymes enter cells
3. Proteolytic cascade → kill cells

• Usually MHC1 molecules send signals to prevent CD8 cells from killing it

Question 10

Mechanism of influenza

Answer 10

• Viral infection, antigens presented on MHC1 molecules (asthma on MHC2)

1. TLR (within molecule) recognises viral infection
2. interferon spreads to neighbouring cells
3. turns off protein synthesis & ↑ anti-viral mechanism
4. CD8 attacks infected cells
5. CD8 apoptose afterwards (due to ↓interferon signals)
6. Tm (t-memory cells) survive → trigger B-cells to have long term defense