Immune 9 - WRAP UP Flashcards
What happens if bacteria make it past our first defences - LOOK AVER THIS SLIDE OF LECTURE
- Inflation makes capillaries leaky - neutrophils squeeze out of the leaky capillaries and enter tissue
- Neutrophils are attracted to the site of infection by chemicals released by damaged/infected cells, or associated leukocytes (especially macrophages)
- bacteria are phagocytoses. Lysosomal enzymes in the phagolysosome kill the bacteria
Immunity to pathogens is usually a combination of cell mediated immunity and antibody production
Viral antigens
- viral proteins can enter both the phagolysosome and cytosol of DC
- phagolysomal antigen will be loaded onto MHC-11 for CD4 (helper) T cell stimulation
- cytosolic antigen will be loaded onto MHC-1 for CD8 cell stimulation
How to get rid of virus by killing the cell that they are living in
CD8 T cell has become activated and is now cytotoxic - it has granules present which coven be released when trigggered
- CD8 cell will only release cytotoxic granules (granzyme / perforin) if its triggered appropriately
- the trigger is the recognition of virus peptides on the MHC-1
- CTL has a T cell receptor that mecognises the peptide MHC-1 complex
- the granules that are released contain granzyme and perforin (cell killing enzymes) - this leads to an ordered destruction of the cell that contains the virus - Neurophille or macrophage or dendritic cell can then eat it up
Colonial selection
Selective expansion of lymphocytes that interact with antigen
- only for T cells specific for the peptide
- T cell is activated and undergoes extensive cell division - producing effector cells as well as formation of memory cells
Bacteria in Dendritic cell
- bacterial proteins enter the phagolysosome of DC
- phagosomal antigen will be loaded onto MHC-22 for CD4 (helper) T cell stimulation
- helper T cells stimulate B cells to make antibody
- only B cells that recognise anitgen are activated -then turn into plasma cells secreting antibodies
(Forming memory cells among the way)
Antibodyclass switching: the class or isotope alters the function of the antibody - not the specify (IgM —> IgG —-> IgA —> IgE)
Colonial expansion for B cells
- selective expansion of lymphocytes that interact with anitgen
- antigen recognised by B cell is called native antigen - not processed to peptides - provides some of the signal that the b cells require to undergo differentiation into plasma cells and memory cells - also requires cytokines
- only B cells that are specific for the native antigen tho!
MHC-1 LOADING
What a BD8 cell will be looking at
MCH-11 loading
Antibodies binding to defined regions (antibody binding sites) on a alrger structure
- antibodies bind native antigens
- severeal different antibodies may target a single type of microbe
- term native antigen means that the antigen doesn’t not have to be processed down to a peptide of loaded onto MHC
- antibodies can recognise just any structure
- antibodies bind tightly to discrete parts on the anigen
Isotopes during the immune response - B cells can genetically switch the heavy chain to change c;ass (isotope) - this doesn’t change the antibody - spefifify but does change the function of the antibody
- constrain region of heavy chain alters properties
- IgM is good at start of immune response as it is good at activating complement
Primary vs secondary immune responses - formation of antibody classes and lymphocyte differentiation state
Vaccines save lives example
- administered to mimic an infection without exposing you to danger - can still use live material (crippled / mutated / cultured tho) - wont cause disease but will cause immunity
Live attenuated: mumps, measles, rubella, polio-Sabin
Killed: polio-Salk, some SARS-CoV2 and some influenza vaccines
Sub-unit protein: tetanus, SARS-Cov2 (maybe just the spike protein)
Sub-unit mRNA: SARVS-CoV2 (e.g Pfizer or Moderna vaccine)
- body have to do the work of producing the protein - spike
MRNA is in lipid coat
Adjuvants - usually requires for sub-unit vaccines
- Adjucents are immune stimulants - non specific - added to vaccines that enhance the activation of anitgen presenting cells
- for example: the mRNA SARS-2 vaccine is intrinsically adjuvanted: the lipid- encapsulated mRNA is immunostimulartory
- RNA can stimulate Toll-like receptors (add o activation of APC
- sometimes adjuvant is intrinsic (already there) sometimes it is added
