Immunological Tolerance And Autoimmunity (Ch. 9) Flashcards
Define immunological tolerance
A lack of response to Self-Ag that is induced by exposure o lymphocytes to these Ag.
What are Ag called that induces tolerance
Tolergenic
Define central tolerance
Developing lymphocytes meet Self-Ag in central lymph organs
Define peripheral tolerance
Mature lymphocytes meet self-Ag in secondary lymph nodes
Immature T-cells in Central Lymph organs get a strong TCR reaction to self-Ag, what happen
Apoptosis
Define AIRE
Protein responsible for expression of peripheral Self-Ag into the thymus
What does a mutation in AIRE cause
Autoimmune polyendocrine syndrome - Self-Ag are not expressed in thymus by APC, thus T-cells self-react
Self-reaction in peripheral lymp[h organs is suppressed by what
Regulatory T-cells
How does DC and T-cell react in terms of co-factors
DC has B7 and T-cell expressed CD28 to meet it
How does CTLA-4 work
Removes B7 from APC, thus stopping co-factors and stimulating anergenic cell
How does PD-1 work
Contains ITIMS that stops signals within T-cells
How do regulatory T-cells stop auto-immunity
When Tc recognized self-ag in thymus, transcription factors FoxP3 is initiated, turning T-cell into regulatory T-cell which expresses CD 25 and IL-2
This then inhibits the cells
What is IPEX
An autoimmune disease caused by a mutation of the FoxP3 gene
What are two other ways Self-Ag recognized cells can die
No-costimulators Death domains (initiated by FasL on TC and Fas)
Define receptor edits in B-cell self-Ag recognition
Immature B-cells express RAG which then allows for recombinant LC switching
This leads to receptor editing which allows the B-cells to ignore self-ag
