Cell mediated immunity Flashcards
give an example of an intracellular pathogen ?
viruses and bacteria
give examples of extracellular pathogens ?
ectoparasites such as lice and some bacteria
what type of pathogen size wise is a virus ?
a microscopic one
is a protozoan parasite a unicellular or multicellular ?
unicellular
is a tapeworm multicellular or unicellular ?
multicellular
what does it depend on in a pathogen on what immune response is given ?
the size of the pathogen
what cannot be done if the pathogen is too large ?
it cannot be phagocytosed whole
what is a cell mediated response ?
an immune response that involves cells
what do the resident cells at the site of entry do ?
they recruit innate cells to the site
what type of cells are involved in a cell mediated response ?
innate and specific cells
what are the effector responses ?
this is when a response to do something occurs such as for phagocytosis to occur
an effector response is the antibody based agglutination , what does this mean ?
it is the clumping of particles
describe the antibody mediated cytotoxicity ?
mechanism of cell-mediated immune defense whereby an effector cell of the immune system actively lyses a target cell, whose membrane-surface antigens have been bound by specific antibodies.
list the innate cells involved in cell mediated immunity ?
Nk cells
basophils
granuloytes
mast cells
what are the specific cells involved in cell mediated immunity ?
the direct effect cytotoxic T cells
antibodies
how does recognition occur in innate cells ?
the pathogen associated molecular pathways (PAMP’s) bind with the pattern recognition receptors (PRR’s)
how does the specific B and T cells go through recognition ?
the specific amino acid sequence of proteins results in antigen - antibody binding and T cell receptor binding.
if the site of an extracellular infection is in the interstitial spaces , blood or lymph how is protection achieved from a pathogen ?
by complement
phagocytosis
antibodies
if the site of an extracellular infection is the epithelial surface how is protection against the pathogen achieved from say gnorrhoeae?
antimicrobial peptides
antibodies especially IgA
if there is an intracellular infection in the cytoplasmic cells of say a virus how is the protective response ?
NK cells
cytotoxic T cells
if the intracellular infection is in the vesicular cells of say leishmania then how is this fought ?
by using T cells and NK cells
macrophage activation
how does blood clotting help in fighting a pathogen ?
it limits the spread
in terms of time what is the difference between specific cells and non specific cells ?
specific cells take time to be produced while the non specific cells can respond first to try and control the infection
an effector cell is Th1 for intracellular immunity , what do these do ?
they eliminate intracellular pathogens by activating macrophages through secreting IFN gamma.
An effector cell is the Th2 for extracellular immunity to a pathogen , what do these do ?
they recruit eosinophils and basophils to eliminate and try to eradicate the pathogen
whats the cells 3 cells that carry out phagocytosis ?
macrophages and neutrophils and dendritic
what is produced when respiratory burst occurs ?
superoxide
1st stage of phagocytosis ?
the cells has arms called pseudopod that surround the pathogen
2nd stage ?
the lysosome then fuses with the phagosome to form a phagolysosome and the enzymes from the lysosome digest the pathogen.
what are the toxic products called that can be produced ?
nitric oxide
hydrogen peroxide
how can the rate of phagocytosis be increased ?
by the antibodies labelling the cell called opsonisation
how is the waste excreted ?
by exocytosis
what do our own cells contain ?
MHC
list some granuolyctes ?
basophils neutrophils eosinophils NK mast cells
what does a granulocyte contain ?
granules that contain toxic products
what occurs when recognition occurs in the granulocytes by the receptors ?
the toxic products are released from the granules.
what is the function of cytotoxic cells?
Cytotoxic cells are used to lyse body’s own cells – get rid of abnormal cells or pathogen infected cells
does the pathogen contain MHC ?
nope only the bodies own cells
how does the cytotoxic cells recognise the bodies own cells ?
by the MHC
do the cytotoxic T cell lyse the pathogen directly ?
no
is CD8+ a cytotoxic T cell ?
yes
what is recognition in a cytotoxic T cell dependent on ?
the amount of MHC expressed
what type of ligand does a cytotoxic T cell contain ?
a FAS ligand which has interaction with the target cell
what is an immunological synapse ?
this is what allows the cells to be in close contact and granules pass through
what does perforin and granzymes do ?
they induce apoptosis
does inflammation occur when apoptosis happens and is this good or bad ?
no inflammation which is good as this means no healthy tissue is damaged
perforin is found in granule of cytotoxic T cell , role ?
aids in delivering contents of granules into cytoplasm of target cell
granzymes found in granules of cytotoxic , role ?
these are serine proteases that activate apoptosis once in the cytoplasm of target cell
granulsin is found in granules of cytotoxc T cell , role ?
it has antimicrobial actions and can induce apoptosis
what does the rapid delivery of granules result in ?
polarisation of the granules before exocytosis occurs
when the death signal is released and this causes a cell to die , what occurs ?
a caspase cascade occurs
are granules released before or after the target cell is stimulated or direct death signal ?
after
do the T cells just kill one cell?
no they go on to kill the next target cell as they are serial killers
do NK cells have one type of receptor or more?
they have 3 types
what’s the 2 responses of a NK cell ?
it can either activate killing by inducing apoptosis or it inhibits killing
what does interferon gamma activate ?
macrophages
helper T H2 cells explained ?
activated by IL4 IL-5 IL 10 and causes recruitement of eosinophils and basophils and cause antibody production as B cells activated.
TH17 explained ?
activated by Il-17A and involved in antibody prodcution
what is a granuloma and cyst ?
These are cells that can form organized structures – granulomas or tissue cysts . They seal off the pathogen and this starves it of nutrients and oxygen which can cause damage at the site of infection
