immunology 1 Flashcards
The purpose of the immune system (4)
Protect the host from pathogenic microbes.
Tissue damage is also recognised by cells of the immune system - it is important in tissue repair
Failure of the immune system leads to increased susceptibility to infection and sometimes cancer.
Regulation of the immune system can become unbalanced which can lead to autoimmune disease and allergy.
What is the primary response (4)
Primary Response - the first time the host has seen this particular virus
The initial response is the innate immune response.
Early peak of type 1 interferon - interferes with the replication of the virus
Peak in NK cells - can recognise infected cells and lyse them
What are two stratergies used to make receptors
Strategy 1
Molecular patterns
Hundreds of receptors
Germ-line encoded
Strategy 2
Precise molecular structure
Millions of receptors
Generated by random recombination of gene segments
Advantage and disadvantage of Pattern recognition receptors
Many cells can be made with the same receptor-rapid response
limited receptor diversity
Advantage and disadvantage of recombination gene strategy of making receptors
Not many cells with similar receptors so you need to have great expansion which takes time
massive diversity of receptors-potential for auto immunit
what are the two types of triggers for Pattern recognition receptors
PAMPs – Pathogen-Associated Molecular Patterns
DAMPs – Damage-Associated Molecular Patterns
What are b cell antigen receptors and were do they bind
membrane bound antibody
binds to intact antigen
Describe t cell receptors
made of two protein chains on the cell surface
Binds to processed antigen fragments presented at cell surfaces
What is the site that antigen receptors bind too
epitope
Describe innate immunity (6)
Present from birth
Relies on pre-formed and rapidly synthesised components
If an infection happens, the components are already there to deal with it.
Limited specificity
Only recognises molecular patterns to do with danger.
uses strategy 1 receptors
What is Acquired/Adaptive immunity (7)
Acquired after exposure to the pathogen
No pre-existing acquired response
Depends on CLONAL SELECTION - expansion of the clone of lymphocytes which recognises the particular pathogen - selection of appropriate lymphocyte to fight the pathogen.
Slow - takes days
Specific
Gives immunological memory
Uses strategy 2 receptors
What does the innate immune response do and what are the two main consequences
destroys invading nucleic acids (e.g. viruses) in the cytoplasm
activates inflammatory pathways, signals for recruitment of immune system cells to sites of damage/infection
elicits type 1 interferons, for anti-viral defence
two main consequences:
“buys time” while the adaptive immune response starts
promotes
directs the appropriate adaptive immune response
Name some Physiological barriers (5) and anatomical barriers (3) used by innate immunity
Low pH Secretion of lysozyme Interferons Anti-microbial peptides Complement
Skin
Mucus - trapping microbes
Cilial propulsion on epithelia
How does the immune system clear the pathogen?
Cytotoxic T Lymphocytes (CTLs) kill infected cells-
Destroy infected cells by injecting lethal enzymes
Antibodies bind to the pathogen and direct phagocytes to come and ingest them
Define antigen
a molecule that reacts with antibodies or T cells.
