Immune response to pathogens Flashcards
What are the three different types of pathogen that the immune system has defences against
- Intracellular
- Extracellular
- Helminth parasites
What is immunopathology?
Immune responses to pathogens that are the capable of causing tissue injury
What are the 4 different types of PRR receptors that recognise PAMP ligands?
- Toll-like receptors – TLRs – various locations
- C-type lectin receptors – CLRs – cell surface
- RIG-I like receptors – RLRs - cytosol
- Nod-like receptors – NLRs – cytosol
What immune response occurs when TLR 7 interacts with a virus?
it activates IL-12 cytokines which causes naive T cells to become T helper cells which induce interferons
What immune response occurs when a fungus/ bacterial polysaccharide binds to the c-lectin receptor dectin-1 ?
There is expression of IL-6 and IL-23 which polarises cells to become IL-17 producing TH17 cells, this the promotes the production of neutrophils and macrophages
What is the first signal in T- Cell activation?
antigen-specific TCR engagement
what is the second signal in T cell activation?
contact with co-stimulatory ligands
What is the third signal in T cell activation?
cytokines directing T-cell differentiation into distinct effector cell
types
How do dendritic cells link the adaptive and innate immune response
they bring antigens from the site of infection and present them to T helper cells in lymph nodes which activates the T cells, allowing them to differentiate
What is the function of igA, igG, igM
virus and toxin neutralisation
What is the function of igG on macrophages
opsonisation
What is the function of igM on tumour cells?
complement fixation and formation of the membrane attack complex
What is the function of a class I interferon?
made up of interferon alpha and beta, they are secreted by virus-infected cells
What kind of infection does the MyD88 adapter protein defend against?
Invasive bacterial infections
What kind of infection does the TLR-3 protein defend against?
Herpes simplex encephalitis
What kind of infection does the Th1 pathway defend against?
“atypical” environmental mycobacteria
What kind of infection does the tH17 pathway defend against
Mucocutaneous candidiasis (fungus),
skin bacterial abscesses
How do viruses typically enter host cells
through a cell-surface receptor, the genome replication is often error-prone which leads to mutations
What is the function of a type II interferon?
modulator of adaptive immunity
What is the difference between Killer cells and Cytotoxic cells?
Killer cells are part of the innate immune response and dont need to be activated to attack cells
Cytotoxic cells are part of the adaptive immune response and attack viruses when activated by an antigen
What is the role of antibodies in the adaptive immune response?
They block infectious viruses early on in the course of infection
What are five ways viruses can evade the immune response
- Inhibition of apoptosis
- Inhibition of type 1 interferon
- production of immune modulators
- engagement of inhibitory pathways
- effection of immune cells
How does antigen drift occur?
It occurs due to the high mutation potential of the RNA genome
the RNA viruses undergo mutation and recombination which alters their genome
How does immune evasion occur in influenza A viruses?
- antigen shift occurs when different virus types try to infect a single cell
- RNA genome segments can then be swapped
- this creates new HA/ NA combinations
- a population may have little to no resistance against a new population
