Week 16 Flashcards
What is immunological tolerance?
Specific unresponsiveness to an antigen that i induced by exposure of lymphocytes to that antigen
What is self-tolerance?
The idea that all individuals are tolerant of their own antigens
What does a breakdown of self-tolerance result in?
Autoimmunity
What are the potential fates for lymphocytes that recognise elf antigens in the generative organs (thymus, bone marrow)?
Mainly death via apoptosis
Some B cells may use receptor editing to change their specificity
Some T cells may differentiate into Treg cells
What is anergy?
A state of unstable metabolic arrest affecting lymphocytes that can lead to apoptosis
What is the effect of CD80/86 on an APC interacting with CTLA-4?
The T cell is switched off (homeostatic control)
What does CTLA-4 interact with on APCs to cause the T cell to switch off?
CD80/86
What are the two main ways Treg cells inhibit the induction or effector functions of other lymphocytes?
Production of down regulatory, immunosuppressive cytokines (eg. TGFβ, IL-10, IL-35)
Interference with receptor signalling pathways
What are the two main populations of Treg cells and what are their roles?
Thymic (natural) - induced by self Ag recognition during T cell maturation (deal with self Ag)
Induced iTreg - induced in the periphery (deal with foreign Ag)
Both thymic and induced Tregs share phenotypic features. What are two of these features?
CD4
High IL-2 receptor (CD25)
Low IL-7 receptor
Foxp3 transcription factor
Naive CD4+ T cell precursor cells can differentiate into three subsets of effector T cells, what are they?
Th1, Th2 and Th17
Naive CD4+ T cell precursor cells can differentiate into several subsets of Treg cells, what are they?
naturally occurring Treg cells (nTreg)
induced Treg (iTreg)
Th3
Tr1
What is immunological ignorance?
Autoimmune lymphocytes are kept in ignorance by hiding autos behind anatomical barriers
What is foetomaternal tolerance?
The prevention of a maternal immune response against a developing foetus
