Autoimmune Disease Flashcards
What is an autoimmune disease due to?
Response to self-antigen
Loss of tolerance
What is immunological tolerance?
Unresponsiveness to an antigen that is induced by previous exposure to that antigen.
What should B and T cells not react to?
Self tissue
What are the 2 types of tolerance that prevent the development of autoimmune diseases
Central tolerance and peripheral tolerance
What parts of the body are involved in central tolerance?
Bone marrow and thymus
What happens in the bone marrow with central tolerance?
One of 2 things can happen to the developing B cells that create antibodies that match antigens in the bone marrow
What 2 things can happen to the developing B cells that create antibodies to the developing B-cells?
Clonal anergy
Clonal deletion
What is clonal anergy?
The cells are made inactive so that they can be released but make no response to antigens
What is clonal deletion?
The cells die and are never released into the circulation
What happens in the thymus with central tolerance?
Developing T cells in the thymus are not selected if they do not recognise self MHC but those that recognise self-peptide plus self-MHC with high affinity are negatively selected and die through apoptosis.
Why is peripheral tolerance important?
Some cells that can recognize self will still enter the periphery
What are some important mechanisms of peripheral tolerance?
Anergy
T-regulatory cells
What is anergy in terms of peripheral tolerance?
T cell recognizes antigen presented on an MHC molecule but does not respond as there is no costimulation. The cell becomes anergic or non-responsive.
What is the function of the T cell regulatory cells in peripheral tolerance?
They inhibit neighbouring T cells
What are autoantibodies?
Antibodies directed at normal cellular components- autoantigens.
