Autoimmunity Flashcards
What is autoimmunity?
It arises when there is a breakdown of immune tolerance
What is immune tolerance?
It refers to the unresponsiveness of the immune system to self antigens (tolerogens)
What are autoimmune diseases?
These are diseases in which the immune system attacks the body’s own tissues
What are autoantibodies?
These are antibodies directed at normal cellular components (autoantigens)
What are the two mechanisms in which immune tolerance is obtained?
Central tolerance
Peripheral tolerance
What is central immune tolerance?
It is the process by which self-reactive B and T lymphocytes are destroyed in the primary lymphoid organs
Describe the process of central immune tolerance
T lymphocytes developing in the thymus are exposed to self-antigens from a range of tissues
This ‘educates’ them about self-antigens. T lymphocytes with receptors that react strongly with self-antigens are destroyed through a process called negative selection
Those that do not react strongly with self-antigens are able to proliferate and leave the thymus to circulate throughout the body
What are the two primary lymphoid organs? Which cells are associated with each?
Bone marrow (B cells)
Thymus (T cells)
What is peripheral immune tolerance?
It includes deletion of self-reactive lymphocytes by apoptosis
It includes suppression of self-reactive lymphocytes by regulatory T cells
It includes induction of anergy
What is anergy?
This is when lymphocytes are rendered unresponsive to self-antigens
What is the first checkpoint of immune tolerance?
Central immune tolerance
What is the second checkpoint of immune tolerance?
Peripheral immune tolerance
What are the five risk factors of autoimmune diseases?
Genetic Predisposition
Female
Young Age
Infections
Drugs
What three genes are associated with autoimmune diseases?
Human leukocyte antigen (HLA)
AIRE gene
MHC polymorphisms
What mechanism results in infections and drugs causing autoimmune reactions?
Molecualr mimicry
