Hypersensitivity and autoimmunity Flashcards
what are the 5 main classes of antibodies
IgG IgA IgM IgE IgD
which hypersensitivity types are antibody-mediated
types I, II and III
which hypersensitivity types are cell mediated
type IV
what types of hypersensitivity are there
type I
type II
type III
type IV
Type 1 hypersensitivity
IgE mediated
allergies
an innappropriate inflammatory response to an environmental pathogen- allergen
immune response activated over something normal like pollen
type 2 hypersensitivity
IgG mediated
antibodies cell to body’s own cells and cause cell lysis so common cause of BLOOD DISORDERS
anemia
Type 3 hypersensitivity
IgG too but different to type 2
occurs when there is an excess of antigen which means immune complexes are deposited in tissues instead of being removed by phagocytes
by being in tissues this causes neutrophils to be recruited
neutrophils release inflammatory cytokines
damages tissues
E.G LUPUS, ARTHRITIS
type IV
cell mediated, delayed- takes a few days
involves CD4 T helper cells (Th1)
-activated by an APC. When the antigen is presented again in the future, the memory Th1 cells will activate macrophages and cause an inflammatory response. This ultimately can lead to tissue damage.
So it’s a normal response by T cells but an unnecessary one as allergen shouldn’t normally be detected as foreign it’s just some people are more sensitive to it
DIABETES, TRANSPLANT REJECTION, DERMATITIS
what is hypersensitivity
refers to undesirable reactions produced by the normal immune system, including allergies and autoimmunity.
an ‘over reaction’ of the immune system
interleukins function, common examples
regulate immune response by pushing a CD4 T-cell to become a specific type of T helper cell IL-21 IL-17 IL-4 IFNgamma
what does IL-21 do
pushes a CD4 cell to become a T- follicular cell which helps B-cells make antibodies
what does IL-17 do
pushes CD4 cell to become a Th17 cell which has a role in autoimmunity
what does IL-4 do
pushes CD4 cell to become a Th2 cell which responds to extracellular (ie Th2 will go and look for extracellular antigen)
what does INFgamma do
pushes a CD4 cell to become a Th1 cell to respond to intracellular pathways
how do interleukins regulate immune response
for example IL-4 pushes CD4 cell to become a Th2 cell which then produces IL-4 (chemokine) and this IL-4 feeds back and influences the Th2 cell to make LOTS more Th2 cells
