atypical immune response Flashcards
tuberculosis basic info
very slow growing -> colonies will take several weeks to appear in culture
infection of the lung (predominantly)
apical destruction
growth at higher pO2
- higher at top of the lungs
can lie dormant
what is the normal spongy architecture of the lung replaced by in TB
caseous necrosis
what are granulomas and where are they found
flecked, sand-like, grain appearance
surface of the lungs
surrounded by activated macrophages and multinucleate cells
what type of infection is TB
respiratory infection (droplets
what is the immunity response to tb
cell mediated is crucial
macrophages are key to controlling cell
T cell production of interferon gamma
cytokines involved in this process
may still fail to clear it
what are the two ways that tb evades lysosomes
subverts intracellular trafficking following phagocytosis
resistance to phagosomal acidification
how does tb subvert trafficking following phagocytosis
bacteria alters phagosome so that it becomes covered in coronin (actin associated protein)
inhibits the ability of the phagosome to fuse with the lysosome
how does tb resist phagosomal acidification
lysosomes operate at low pH, which increases closer to neutral when the phagosome fuses
- allows the lysosome to function
tb pumps out protons (H+) to reverse this change
prevents lysosome functioning
describe the pathway to disseminated disease with tb
BCG (live vaccine) -> lack of interferon-gamma/ lack of interferon-gamma receptor -> disseminated disease
- mutation in some families
what are some key cytokines in tb clearance and what do they do
il12 / il12 in dendritic cell
leads to increased production of interferon gamma by T cell -> increased activation of macrophages
how can we determine if people have/ have had tb
Mantoux reaction
also T spot test (similar to ELISA test)
describe the CD8 response to HIV
keeps HIV in check
when CD8 calls are depleted, the viral load peaks
- CD8 is bringing virus under control
- not final response
many mutations
- epitomes don’t bind to CD8
- allows evasion
what is the plateau of mutation for HIV
set point
any more mutation would have a negative impact on the virus
increases chances of survival
describe the antibody response to HIV
after ~3months - a year antibody response is observed
similar issue to CD8
what vector is dengue spread by
mosquitoes
what are the symptoms of dengue
fever, rash, extreme myalgia
how does dengue fever destroy the epithelial cell-capillary barrier
variety of inflammatory cytokines produced by viral-infected macrophages can eventually lead to the barrier being broken down
allows fluid from capillary to enter the tissues
what is oedima
fill up lungs/ areas of the brain
can proceed to extreme illness or death
what does severe dengue cause
severe plasma leakage, haemorrhage
multi system organ failure
brain impairment
congentival haemorrhage
what causes severe dengue
4 more serious types across the globe - distinct but related
not non-sterilising but still atypical
recovery from one gives lifelong immunity to that strain
a secondary infection by one of the different strains can lead to dengue haemorrhagic fever (DHV)
what is different about the immune response to DHV
antibody combines with the virus but doesn’t neutralise it
acts as opsonin - enhances uptake of virus into monocytes and macrophages
increases cytokine activation and infection of epithelial cells
more complications
what is the risk with the dengue vaccine
risk of immune enhancement with antibodies (DHV)
when it was introduced in Indonesia, could give good protection if you’ve had a previous infection with the same strain
- if they hadn’t been exposed to Dengue, then the vaccine made it a lot worse
young children that haven’t lived long enough
vaccine has been withdrawn
