The Adaptive Immune system & response Flashcards
Key features of the adaptive immune system
it is specific/aquired
is highly specialised but develops slowly
3 functions of the adaptive immune system
recognise self and non self cells
generate responses to eliminate specific pathogens
develop immunological memory
2 types of T cells
CD4 helper cells
CD8 killer cells
(CD = surface marker expressed)
how are T cells activated
Naïve CD4 T cell interactive with dendritic cell causing differentiation and proliferation
How do T cells protect themselves
release interleukin 2
this also produces more T cells and cytokines
what do T cells become once activated?
Th1 (IL-12) or Th2 (IL-4) depending on which cytokine is produced by the cell
what do Th1 cells do?
cell mediated response
eliminate pathogens that infect host cells (viruses)
causes proliferation of NK cells and Cytotoxic T cells
what do Th2 cells do?
humoral mediated response
defence against extracellular bacteria/parasites
aid activation - macrophages, B cells
`what do Cytotoxic T cells do?
Interacting with MHC I on infected cells and then killing the infected host cell
(similar to NK cells)
how do Cytotoxic T cells kill?
Perforin / Granzymes system
fas-ligand interaction causes apoptosis
where are B cells produced
bone marrow
what happens when a B cell is mature
expresses a B cell receptor (immunoglobulin)
how are B cells activated and what do they do
activated by interaction with T cells (MHC II)
produce antibodies
what is B cell clonal expansion?
trail and error find right anti body
what 2 cells are produced by B cell clonal expansion and what do they do
Plasma cells - produce antibodies
Memory B cells - remember how to produce antibody
why is isotype switch important?
allows T cells to be manipulated to produce a different class of immunoglobulins
What are antibodies
small proteins that help the rest of the immune system work (highly specific)
what do antibodies do? (3)
activates complementary system (classical pathway)
causes phagocytosis
embed themselves into cell surfaces waiting for future infection
5 classes of antibodies
Ig M Ig A Ig D Ig E Ig G
antibody Ig M features (pentametric)
first antibody produced can bind up to 10 antigens
jack of all trades (lower affinity)
antibody Ig A features (secreted)
second most abundant
present on mucosal surfaces - prevent binding (prevents infection of host)
antibody Ig E features
key for parasites and allergens
largest antibody
how do antibodies work
they neutralise pathogens using toxins or prevent pathogens entering cells
what is pathogen opsonisation?
helps phagocytes recognise and engulf a pathogen
what is antibody mediated cell cytotoxicity
antibody binds to surface of target cell helping NK / T cells release their enzymes for apoptosis
how does immune memory work
correct antibody is remember and mass produced following infection meaning the less effective IgM is not required and the infection is fought off
what are the different types of immunity (4)
Passive natural (placenta transfer)
passive artificial (Im injection)
active natural (beating an infection)
active artificial (vaccination -simulates immune response)
how do bacterial infections start?
when there is a breaking/hole in the epithelial cells
they will start replicating
how is bacterial infection fought off (first stages)
macrophages (phagocytosis) -> produces cytokines -> activates mast cells to degranulate
what do degranulated mast cells do
make blood vessels more permeable (histamine) allowing neutrophils and complementary proteins to come to the site of infection (chemokine gradient detected)
how is bacterial infection fought of (secondary stages)
complementary system, T cells and B cells = IgM produced prior to best antibody being made and the IgG (specialised)
How does a viral infection response differ from bacterial (3)
IFN-a produced by host epithelial cells (prevents cell reproducing & ^ MHC I expression
cells eventually burst releasing more viruses but they are dealt with and antibodies are processed
more NK & cytotoxic activation
