autoimmunity 1 Flashcards
how many people in the uk have an autoimmune disease and in how many people
4 million
1 in 5 people
how many people are affected by rheumatoid arthritis
1 in 100 people
what are autoimmune diseases
a family of diseases that are chronic and disabling where the immune system attacks the body’s own tissue and organs
what are the risk factors for an autoimmune disease
environmental triggers such as infectious agents
hereditary genes
lifestyle considerations
what has a significant effect on autoimmune disease
b cell progression
what is the process of a normal CD4 t cell response
APC recognises pathogen
internalisation and interaction with MHC
presentation by MHC
MHC interaction with a TCR complex with peptide
danger signal/ costimulation
t cell proliferation
t cell signal launches immune response via b cell and cd8 cell
when will an autoimmune disease occur
when the usual control of lymphocytes are interrupted which interrupts lymphocyte impression
when there is an alteration in cells and tissue meaning they are not longer recognises as self
what can trigger the autoimmune response
bacteria, viruses, toxins and some drugs
what is tolerance and what happens when this is broken down
the prevention of an immune response to a particular antigen
autoimmune disease
if a MHC is interrupted
the person could become more susceptible to an autoimmune disease
what does t cell activation consist of
recognition of a self MHC and a foreign antigen
what is central tolerance
central tolerance is the elimination of t cells that recognise the body’s self-antigens
in central tolerance, where does positive regulation take place and what is the process
thymic cortex
this is where cells that have a receptor that binds with MHC molecules and selected and are allowed to survive
cells that do not interact with MHC molecules are destroyed via apoptosis
in central tolerance, what is negative selection and where does it occur
this is where the cells that bind with high affinity to self-antigens and/ or self-MHCs are killed to prevent an autoimmune response
the ones that do not mature into CD8/ CD4
this occurs in the thymic medulla
what happens to cells that have an intermediate affinity for a self-antigens
they work as t cell regulators to suppress any reaction to self antigens
what is perpherial tolerance
is the deletion or anergy of lymphocytes located outside of the immune organs that recognise self-antigens
what is anergy
anergy is the lack of response to an antigen
what can cause anergy in t cells
lack of accessory signals in the present in the engagement of TCR and MCH peptide
what do treg cells repsond to to produce an inhibitory response and why
antigens
to suppress t cells from self reacting
why is anergy important when a t cell does not have accessory signals present
to prevent self reactivity
what can happen to a cell with low self antigen affinity but why can this be a problem
they can escape tolerance
if a stimulus is strong enough, they can be activated
how do t cells distinguish self from non-self (three wyas)
-they must encounter the ligand (self antigen) when the they are still immature
-when there is a high and constant concentration of ligand
-bing to the ligand without costimulation
why do b cells need to be taught self tolerance
as antibodies can react to self-antigens and either trigger the complement system or opinization
when does central tolerance occur in b cells and where
when the immature b cell is presenting igM
in the bone marrow
