Describe the adaptive response
- Powerful- antigen specific
- Immunilogical memory can be developed
- More rapid subsequent encounters
- Follows the induction of innate immunity
- System in the lymph nodes
What are the advantages of the adaptive response?
- High antigen specificity
- Highly effective
- Memory cells have a quick and effective response at subsequent encounters
What are the disadvantages of the adaptive response?
- Takes a few days to develop
- Ineffective for new pathogens, no memory developed
Describe innate immunity
- Activated by dendritic cells and macrophage digest bacteria
- Soluble mediators and cytokines
- Activate mast cells (release histamines)
- Types of dendritic cells- langerhan, dermal dendritic cells
What is the function of B lymphocytes?
-Differentiates and becomes plasma cells that secrete antibodies
What is the function of Helper T cells?
- CD4 receptor
- Helps immune response through releasing chemical signalling to other parts of the immune system
What is the function of cytotoxic T cells
- CD8 receptor
- Kill infected cells by releasing cytotoxic granules
Describe the activation of adaptive immune response
- 3-14 days
- Bacteria can enter lymph node
- B cells are found in the cortex
- T cells are found in the paracortex
- Activation of the closest point contact, which may be a lymph node
Describe the activation of T cells
- Dendritic cells phagocyte bacteria and present fragments complexed with MHC
- MHCs are found on dendritic surface, presented Helper T cell, CD8 to MHC class 1 and CD4 to MHC class 2
- New T cells can only be activated by dendritic cells, after this any antigen cell can activate
What does MHC stand for?
Major histocompatibility complex
Describe the activation of B cells
- Not fragments, whole antigen
- B cell receptor- antibody bound to membrane, also expresses MHC Class 2
- Binding of antigen to antibody isn’t sufficient for B cell activation, requires helper T cell (IL4)
- Upon activation plasma cells are produced which migrate to medulla of lymph node
What occurs in the activation of the adaptive response
- CD8 continues to kill
- When most cells activated, chemokines released that leafe a trail for T cells to callow along lymph vessels
- Long process as it takes time for proliferation to occur and antibodies to be produced
- Antibodies specific and accumulate in bloodstream
What occurs in the third phase of adaptive response?
- T cells present much more rapidly than antibodies
- Acquired immunity highly specific, generates more efficient response
- releases chemical signals
What is opsonisation?
- Cells chemically modified to have a stronger attraction to cell surface receptors on phagocytes
- Antibodies facilitate phagocytosis
- ADCC- antibody-dependent cellular cytotoxicity
What is the resolution of infection?
- Removal of bacteria
- Establishment of memory
How is memory established?
- Generation of memory T and B cells
- One of the daughter T cells becomes a memory T cell once infection has died down
- Proliferate more rapidly second time (days rather than weeks)
- Some B cells differentiate into memory cells rather than plasma
- Reside in tissue and lymphoid tissue
Why does tetanus infection not usually induce memory?
- Produces a toxin rather than antigen, difficult for immune system to respons
Describe the tetanus infection?
- Damages nervous tissue
- Not lifelong memory
- Boosters required
- In vaccination, toxins are attenuates, may not stimulate immune system as much as actual infection
