Block 3 Flashcards
(33 cards)
what does rhinovirus infect
epithelia cells which leads to a cold
what does hepatitis A-G infect
liver cells
what does HIV infect
CD4+ T cells which leads to Aids
innate immune response for viruses
Type-1 interferon (IFN)
NK cells
Dendtritic cells
adaptive immune system response for viruses
CD4+ helper T cell
CD8+ cytotoxic T cell
B cells
where is cytokine production incduced
virus-infected cells
what does Type-1 IFN do
Induces cells to shut down some of their protein-making functions.
Activates immunoproteasome activity and increases MHC expression
Activates dendritic cells, macrophages and NK cells
how do some viruses try to evade immune response
by switching off MHC-1 expression or inhibiting the processing pathway
what do activated NK cells produce
IFN gamma, which helps activate macrophages and induces T cells towards Th1 phenotype
what are NK cells activated by
recognition of ‘altered self’ altered surface proteins on infected cells suggest infection
what does reduced levels of MHC-1 allow
virus-infected cells to evade cytotoxic T cells
how are cytotoxic T lymphocytes activated
by recognition of specific viral antigen on MHC-1
what activates apoptosis
release of intracellular granules
what do antibodies do
bind to virus proteins and target for destruction, block viral proteins, neutralise viral toxins
what is a parasite
organism that benefits at the expense of another host organism
what cells do not express MHC molecules
Red blood cells
healing response to Leishmania major
macrophage/dendrtitic cells produce IL-12 activating macrophages to kill the intramacrophage parasite.
IFN-gamma from NK cells, TH1 cells activate macrophages which produce microbicidal products eg superoxide, nitric oxide, enzymes
cutaneous leishmaniasis
no activated macrophages, TH2 dependent, IL-4 drives a TH2 response, Th2 cells produce IL-4/IL-13 which inhibit a TH1 response by inhibiting IL-12 production. IL-4/IL-13 inhibit IFN-gamma production and activity
toxoplasma gondii
CD8+ T cells producing IFN-gamma main mediators of resistance
In AIDS patients dormant tissue cysts in the brain reactivate resulting in encephalitis
IgG-coated parasites are killed inside macrophages following phagolysosome fusion
what does antigenic variation result in
parasite persistence
how do the different cell-mediated responses recognise bacteria
Innate- pathogen recognition receptors (PRR)
Adaptive- B/T cells recognise their specific antigen
how do neutrophil extracellular traps (NETs) respond to bacteria
immobilise bacteria at the site of infection, specialised apoptosis (NETosis)
complement-mediated killing of bacteria
Direct lysis of bacterial cell using full pathway
Indirect – act as an opsonin to aid phagocytosis
antibody response to bacteria
bind to bacterial toxins, neutralise effects – stop toxin reaching its active site. Act as an opsonin–clumped bacteria easier to be taken up by phagocytes
Bacteria produce super antigens – class of proteins that can activate a large population of T cells – induce toxic shock
