C3 cell mediated immunity Flashcards
what is a cell mediated response
is any that involves cells
resident cells at the site of entry- and then innate response recruits cells to infection site
innate and specific cells are involved
antibody based effector responses
aggluntination
antibody mediated cytotoxicty
innate and specific cells used in cell mediated immunity
-innate
NK cells, granulocytes, phagocytic cells, mast cells, basophils
-specific cells
direct effect-cytotoxic t cells
indirect via mediators produced ig IFNy, TNF
innate cell recogniton
pathogen-associated molecular patterns (PAMPs) interact with pathogen recognition receptors (PRR)
specific B/T cell recognition
aa sequence of proteins
antibody:antigen binding/T cell receptor binding
cell types and functions of effector module cytotoxicty
NK cells, CD8 T cells
elimination of virally infected and metabolically stressed cells
cell types and functions of effector module intracellular immunity (type 1)
ILC1, Th1 cells
elimination of intracellular pathogens, activation of macrophages
mucosal and barrier immunity (type 2) cell types and funtions
ILC2, Th2 cells
elimination and expulsion of parasites, recruitment of eosinophils, basophils and mast cells
extracellular immunity (type 3) cell types and functions
ILC3, Th17 cells
elimination of extracellular bacteria and fungi, recruitment and activation of neutrophils
what cells can bring about phagocytosis
macrophages or netrophils
summary of phagocytosis
engulf pathogen in phagosome, get induction of respiratory burst, generation of superoxide
lysosomes fuse with phagosome- phagolysosome- enzymes digest pathogen
what are the toxic products produced by phagocytosis
nitric oxide and hydrogen peroxide
what happens to the rate of phagocytosis when target is opsonised
enhanced (>4000x)
what cells contain granules
granulocytes, eosinophils, neutrophils, basophils, mast cells, NK cells
what do granules contain
proteins which recruit other immune cells to site
eg mast cells produce leukotriene B4
perforins action on target cells
aids in delivering the contents of granules into cytoplasm of target cell
granzymes action on target cell
serine proteases, which activate apoptosis once in the cytoplasm of target cell
granulysins action on target cell
has antimicrobial actions and can induce apoptosis
what do cytotoxic cells lyse
lyse body’s own cells- gets rid of abnormal cells or pathogen-infected cells
do not directly lyse pathogen
what is recognition of cytotoxic cells dependent on
dependent on amount of MHC expressed (NK cells) or engagement or T cell receptor and antigen presented on MHC mols on target cell
Fas ligand interaction with Fas on target cell
what is required for cytotoxic cells to carry out their function and why
close contact with target- immunological synapse
formation of central superpolarised activation complex and granules pass through to immunological synapse
how fast is the delivery of granules
rapid
polarisation of lytic granules in cell before exocytosis takes 50-500 secs. avg 200
how many types of granzymes do humans have compared to mice
human- 4
B A K M
mice- 10
what is activated by death signal causing apoptosis, and how many types
activates caspase cascade, at least 12 types of caspases
what are the three types of pathogen recognition receptors on NK cells
- killer immunoglobulin-like receptor (KIR)
- heterodimeric C-lectin receptors (CD94 and NG2)
- natural cytotoxicty receptors
how do cytotoxic T cells know the cell they are killing
target expresses the antigen that matches the specificity of the TCR
granules are induced AFTER stimulation or direct death
cytotoxic t lymphocyte mechanism summary
CTL recognises and binds virus infected cell
CTL programs target for death, inducing DNA fragmentation
CTL migrates to new target
Target cell dies by apoptosis
