Autoimmunity and immunologically mediated disease Flashcards
What are the differences between innate and adaptive immune system?
a) type of response
b) lag time
c) components
d) memory
e) life forms
Innate = non-specific, immediate maximal response, cell mediated and humeral components , no immunological memory
found in newly all forms of life
Adaptive = pathogen and antigen specific response, lag time between exposure and maximal response
cell mediated and humeral components
exposure leads to memory
Found only in jawed vertebrates
What is self tolerance?
Inherent property that allows response against foreign antigens without attacking self
Which immune system is related to self tolerance?
Adaptive
How is tolerance monitored?
Checkpoints
What occurs if tolerance is not monitored and goes wrong?
Autoimmunity
What are the 2 mechanisms of tolerance?
Central and peripheral
What is central tolerance?
Induced during development of T cells in thymus
What is peripheral tolerance?
Control of auto-reactive cells through non-thymus dependent processes
How does central tolerance develop?
In the thymus, autoimmune regulator element (AIRE) is expressed whilst the T cells develop.
This expresses a variety of peripheral tissue antigens.
Recognition of self antigens by immune lymphocyte leads to negative signal causing death or inactivation
Where is peripheral tolerance most commonly found?
In immune privileged sites (eye/brain)
Naturally less subject to the immune response
How can tolerance be achieved in the periphery?
Anergy - T cell receptors can be engaged without co-stimulation
Regulation - Treg cells can suppress other effector functions and enforce tolerance
Failure to develop tolerance means T cells and antibodies are directed against self-antigens what is the result of this?
Tissue damage and altered physiological function.
Tissue damage causes released of more self-antigen = more reaction
Why does autoimmune disease tend to be active for a very long time?
Autoantigens are very difficult to clear
Why are older adults more at risk of autoimmunity?
Smaller thymus with fewer functional lymphocytes
What are the consequences of autoimmunity over time?
Increased incidence of infection
Higher levels of autoimmunity (increased T cells for self antigens)
What can cause autoimmune disease?
Genetic factors
Infection and environment
How can genetics effect autoimmunity?
Affect availability and clearance of auto antigen
Affect expression of co-stimualtory molecules
Why is it suggested that genetic and environmental factors are reacquired to cause autoimmunity?
Many people with genetic factors predisposing them never get the disease
How can autoimmune disease be classified? Why is this imprecise?
By nature of immune response e.g. antibody mediated (type II, III), T cell mediated (type IV)
Imprecise because the immune response is interlinked - problems with antibody production linked to T cells
What is a type II autoimmune response?
Antibody against cell surface antigens
What is a type III autoimmune response?
Antibody complex against circulating antigen
Name a type III autoimmune disease?
Rheumatoid arthritis
Name a type II autoimmune disease?
Autoimmune haemolytic anaemia, pemphigus vulgaris
What is a type IV autoimmune response?
T-cell mediated
