L11 Immunology intro Flashcards
examples innate immunity
toll like receptors
complement pathway
lysozyme
innate immunity response
rapid but low specificity
what can complement be triggered by
antibody (IgM)
carbohydrate
C3b stabilisation on cell surface
three pathways to complement system
classical
lectin
alternative
what pathways use C4b->C2b as an activation molecule
classical
lectin
what enzyme converts C3->Bb and C4b->C2b
convertase
what triggers the alternative pathway
conversion of C3b-> Bb
what is C3a involved in
inflammation
what is C3b involved in
phagocytosis
what pathway is always happening?
alternative
what are toll like receptors
pattern recognition receptors
what do TLR do
recognise conserved microbial structures and transmit signals to the nucleus to alter gene transcription
where are TLR expressed
the cell membrane
and
in endosome
what activates the TLR in the endosomes
double-stranded RNA single-stranded RNA bacterial DNA (undermethylated CpG)
what happens to amino acids in the endosome
become protonated in the acidic environement
what do TLR on the cell membrane recognise
lipoteichoic acid: gram +ve
lipopolysaccharide: gram -ve
Flagellin: mobile bacteria
why don’t commensals in the gut trigger the immune system
they are non-invasive
not near TLR and leukocytes
how are commensals kept out of areas with high amounts of TLR
physical barriers and chemical barriers
skin, mucus
what antibody is produced to protect from pathogens and commensals in the gut
IgA
what does the adaptive immune repsonse involve
MHC, B cells, T cells
how fast does the adaptive immune system respond
slower initial, memory response is rapid, high specificity
what do macrophages do
phagocytosis
express MHC I and MHC II
which cell is the most potent antigen presenting cell
dendritic
what do dentritic cells do?
carry antigen to the lymph nodes for surveillance by T cells
how are DC mainly found
in tissues as sentries
what do DC’s do
capture proteins degrade them load peptides to MHC travel to lymph node activate T cells
what do activated T cells do to B cells
help them make antibodies
which is the most important T cell for starting an immune repsonse
CD4 helper cell
a reason why lymphonodes are helpful
concentrate T cells in one area with DC to activate them
are all the T cells that leave the lymph nodes after seeing DC activated
no, only those that have seen abnormal peptides on the DC
main job of a DC
switch on helper t cells
