immuno and infection Flashcards
4 pathogen niches during infection
Extracellular
Intracellular vacuolar (can be spaces like lysosome or ER, stay within a compartment)
Surface adherent
Intracellular cytosolic
How does an immune response to infection start?
Tissue damage (e.g. injury) Molecular detection of microbes – wrong thing in the wrong place at the wrong time!
what happens after detection
Inter-cellular communication (e.g. interleukins)
what happens after communication
Priming the adaptive immune response
how does an immune response to infection end?
4
Clearing infection
Stopping inflammatory cytokine production
Repairing tissue damage
Remembering the infection – immune memory!
what is Innate immunity
Fast acting, first line of defence, germline encoded receptors
what is Adaptive immunity
Slower but long-lasting, variable receptors that mature over time (DNA recombination)
components of innate immunity
Physical barriers:
Skin, mucous, epithelial cells
Humoral:
Complement, Lectins (collectins, ficolins), Pentraxins, Antimicrobial peptides
Cellular:
Neutrophils, Macrophages, Dendritic cells, Natural Killer (NK)-cells
components of adaptive immunity
Humoral:
Antibodies (immunoglobulins of various types)
Complement
Cellular:
Cytotoxic T-cells, T helper cells, T regulatory cells, B lymphocytes & Plasma cells
in vs ac in specificty
in- broad e.g. structures that are shared by classes
only recognise about 1000 molecular patters
ac- more specific and only specific, antigens
recognise 10^7 antigens
receptors in in vs ad
in- encoded in germline
ad- encoded by genes produced by somatic recombination of gene segments, greater diversity
types of receptors- in vs ad
in- less than 100
ad- 2 imunnoglobins and tcr
but million if variations of each
clone able - in vs ad
in- no
ad- can clone
discrimination between self and non self
in- yes healthy host cells non recognised
ad- yes based on elimination of self reactive lymphocytes
but can be impaired
differences between both immune systems
Timing of the response Cell types Receptors & ligands Cytokines & chemokines Molecular effector machineries
sequence of molecular & cellular events
Microbial molecules V Detection/Ligands or activities V Naïve host-cells V Gene-expression changes/encodes new protiens V Signal transduction (send signal to neignbouring cells to become activated
antimicrobial molecules to fight infection
signals that act autocrine to specilise and activate host to become better)
First responders to injury
Neutrophils are the first to respond (short-lived, ~6 h), followed by macrophages
function of nutrophil
nuetrophil control infection and limit/repair tissue damage
Uncontrolled activities of phagocytes is not good
why
Granulomas
Excessive inflammation & inappropriate adaptive immunity
Tissue damage
Immune response to bacteria that is live
nflammatory cytokines
Antimicrobial genes
Metabolic genes
Immunomodulatory genes
what to molecules that are released by live bacteria (which IL)
MATURE IL B
Immune response to bacteria that is dead
Resolution of inflammation
what is unique to fungi
beta glucan
recognised by what
dectin 1
signialling by what
SRC tyrosine kinase
causes what
Proinflammatory cytokines
Antimicrobial genes
Metabolic genes
Immunomodulatory genes
how are viruses recognised
by rna or dna viral genetic information
what is relased
Interferon production
Proinflammatory cytokines
Antiviral genes
Immunomodulatory genes
what happens when macrophages they are activated
expression of new genes
Induced by microbes & cytokines
what di activated macrophages display
Phagocytosis & Migration Cytokine/chemokine production Expression of cell surface molecules Antimicrobial activity Antigen presentation & T cell activation
how do macrophages and lympocytes communicate
macrophage can produce cytokine that cause t cells ti produce other cytokine helping macrophages to deal pathogens better
when are interferons produced
Detection of viruses or Gram-negative bacteria
what do interferons do
Interferons promote antiviral defence
Interferons are special cytokines
every type of cell csn produce which tupe of cytokines
interferon 1
Immunomodulatory roles
of interferons
Enhanced T-cell responses
Anti-inflammatory actions
Tissue repair
Virus-infected cells are killed by the actions of
cytotoxic T lymphocytes (CTLs) or Natural Killer (NK) cells
do CTLs and NK cells directly kill infected cells (contact-dependent)
yes
what about intracellular
Host cells infected with intracellular bacterial pathogens also undergo forms of cell death (contact-independent)
name 2 antimicrobial enzymes
phagocyte oxidase
iNOS
what does phagoyte oxidase produce
reactive oxygen species (ROS)
iNOC
nitric oxide
what do both do
kill microbes
when are the genes expressed
when they are activated not naive
Type I & III interferons promote
antiviral responses
Inhibitors of virus entry & exit
Inhibitors of viral uncoating and replication
Inhibitors of protein translation
Type II interferon promotes
antibacterial immunity
t cell activataion
Activated macrophages and DCs present antigens in combination with MHC-I or MHC-II to T cells
Cytokines produced by antigen-presenting cells produce a suitable milieu for T-cell activation
E.g. IL-12 promotes T-cell replication
T cells provide cytokines that activate phagocytes
E.g. IFNγ upregulates MHC-II expression for antigen presentation
Responses are specific to general class of pathogens
what are t helper cells
T cells help B cell produce antibodies
when are th1 normoally seen
intracellular bacterial infections
Broad classification of T cell functions
Phagocyte activation
Enhanced killing of pathogens
Inflammation
Direct killing of infected cells
Removal of replicative niches
B cell activation
Antibody production & affinity maturation
Innate lymphoid cells/γδ T cells
A type of early responders (MHC independent actions)
how long does teh innate immunity stay for
12 hours
how long does the adaptive immunity take place for
from 12 hours plus
why does teh immune rsponse get wekaer as you get older
as thymic output decrase se
and t cells are made from the thymus
