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Flashcards in Lecture 2 Deck (36):

What is primary lymphoid tissue 

Site of production for B cells and T cells 

  • Bone marrow and thymus 


What is secondary lymphoid tissue 


sites where B and T cells become activated by antigen 

  • Lymph nodes
  • Pyers patch
  • Adenoid tonsils 


What is lymphoedma

  • Lymphatic obstruction 
  • Inherited 
  • Cancer treatment 
  • Parasitic infections
  • Tissues with lyphodema are at are higher risk of infection


Describe the features of the innate immune system 

  • Rapid responce - mins to hrs 
  • The same responce is produced to a many different pathogens 


Describe the adaptive immune systems 

  • Slow responce - days
  • Unique responce to each individual pathogen
  • Mediated by T cells and B lymphocytes 
  • Immunological memory 


Define acute inflammation 

  • Rapidly cleared by the immune system
  • Lasting immunological memory 


Describe latent infection

  • Controlled by the immune system 
  • Periodic episode of pathogen reactivation and replication 


Decribe Chronic infection 

  • Immune system fails 
  • On-going pathogen replication 


How do the two system act in responce to an infection 


How do the two systems communicate with each other 

  1. Direct communication - Via receptor ligand interactions
  2. Indirect communication - production and secretion of cytokines 


Describe the direct contact between the arms of the immund system

Via receptor ligand interactions 


  • Peptide: MHC or TCR 
  • PAMP: PRR 


Decribe the indirect contact between the two arms 

synthesis and secrtion of cytokines by activated immune cells or injured tissue cells


Give some examples of cytokines 

  • Interferones 
  • TNF 
  • leukoriences 


What do virally-infected cells produce


Interferons - INF 


What is the function of Interferons 

  • Signals neighboring uninfected cells to destroy RNA and reduce proteins synthesis 
  • Signaling neighboring infected cells to undergo Apoptosis 
  • Activates immune cells - natural killer cells 


What are the early innate immune responces 

  • Acute inflammation 
  • Macrophages 
  • Mast cells 
  • NK cells


How does the innate immune system recognise and respond to pathogens 

  1. Recognition phase
  2. Activation phase
  3. Effector phase 


Describe the Recognition phase 

Pathogens express Pathogen associated Molecular Patterns - PAMPs

  • These are common to many different species of pathogen
  • Innate immune cells express Receptors for these PAMPs
  • Pattern-recognition receptors - PRR 
  • PRR - are found on cell surface and intracellularly - for extra and intracellular pathogens 


Give examples of PAMP:PRRS

  1. Toll-like receptor 4 : Lypopolysaccharide LSP (gram -ve bacteria)
  2. Dectin 1 : B - Glucans (fungi)
  3. Toll like receptor 7 : ssRNA (viruses)


What are all the innate immune cells that are tissue-resinant 

  • Macrophages
  • Mast cells
  • Natural killer cells 
  • Dendritic cells 


How do apoptotic cells get cleared from the body

  • When a cell undergoing apoptosis it releases Eat me signals
  • Binds to engulfment receptors on apoptotic body and is cleared 


Decribe the process of phagocytosis 

  • Apoptotic cell will release eat me signals which will bind to engulfment receptors on phagocyte 
  • Formation of phagocytic cup 
  • The cup will extend around the and pinch off forming a phagosome 
  • Phagosome will fuse with a lysosome inside the macrophage 
  • Formation of  phagolysosome causes lysis its contents
  • Debris are released into the Extra-cellular fluid
  • at the same time cytokins like IL-10 are being released to dampen down any unwanted responces 


What happens when this is injury or infeciton to the tissue 

  1. Early innate immune responces are triggered
  • Macrophages
  • NK cells 
  • mast cell

​    2. Pathogens and infected tissue cells are killed

    3. Production of inflammatory mediators 


What is the difference between macrophages phagocytosing pathogens and tissue cells 

  • Phagocytosing tissue cells - will released anti-inflammatory cytokines - IL-10 
  • phagocytosing Pathogens - will released Pro-inflammatory cytokines  + antigen presentation 


What is contained within the phagolysosome 

  • Lysozyme
  • Hydrolases
  • Proteases 
  • Acidification 


Which bacteria can invade phagocytotic killing

  • Salmonella 
  • Staph- aurous 
  • Mycobacteria - TB


How do macrophages deal such pathogens 

  • Enhancement of phagocytosis by pro-inflammatory cytokines - e.g IFNy (NK cells)
  • Leads to production of toxic Reactive oxygen and nitrogen species ROS/RNS 
  • Now can present antigen on surface 


What is the function of Natural killer cells 

Kill virally infected and tumour cells and ignore normal cells 


How can NK cell differentiate between the normal cells and abdnormal cells 

  • Normal cells present MHC Class 1 on their cell surface which allows them to termed normal
  • Where as an infected cell will not present MHC Class one - production of pro-inflammatory mediators


Describe how NK cells kill pathogens and enhance phagocytosis 

  • Virus infectes cell - which will result in altered or absent MHC CLass 1 - This will allow the infected cell to be detected and killed by the NK cells
  • At same time indirect activation of IFNa/b - pro-inflamatory cytokines 
  • Release of IFNy - allows enhancement of macrophages - activation of ROS/RNS 
  • Increased pathogen killing and antigen presentation by macrophage


What are some inflammatory Mediators that are produced during the innate responce 

  • Nitric oxide 
  • pro-inflammatory cytokines - TNFa
  • Prostaglandins/ leukotriens
  • Histamine 


What does production of inflammatory mediators cause 

localised aute inflammation


What are the clinical features of acute inflammation 


What is the acute phase responce 

  • Changes in concentration of plasma proteins in repsonce to inflammation 
  • This is driven by cytokines produced during localised inflammatory responces
  • Changes due to altered protein synthesis in the liver 


What are the acute phase proteins and whats their function 


What is the role of CRP and how is it produced

  • Used as marker for inflammation 
  • Prevents spread of inflammation and prevents systemic inflammation 
  • produced in the liver in responce to production of - IL6 and IL-1b