Immune Tolerance Flashcards
Hypercytokinemia and sepsis caused by?
Too much immune response in a positive feedback loop
Triggered by pathogens entering the wrong compartments or failure to regulate response to correct level
3 phases of cell mediated immunity?
Induction- APC like dendritic cell moves to lymph node
Effector- activated T cells move to affected tissue and carry out action
Memory- contraction phase, memory pool
3 signals required for immunity?
Antigen recognition
Co-stimulation
Cytokine release
Tolerance definition?
Specific unresponsiveness to an antigen that is induced by an exposure of lymphocytes to that antigen (tolerogen vs immunogen)
B cell central tolerance?
If immature B cell, IgM cross links with antigen then apoptosis occurs
T cell negative selection?
If T cell binds to self-MHC too strongly then apoptosis occcurs
T cell positive selection?
If T cell binds to self-MHC weakly it survives
AIRE function?
AutoImmune Regulator promotes self tolerance by allowing thymic expression of genes from other tissues. Mutations in this result in multi-organ autoimmunity
What is peripheral tolerance?
Destroying any self-reactive lymphocytes which enter the circulation
How can B cells break tolerance?
Somatic hypermutation can occur after leaving the bone marrow, normally good but can be bad
Anergy?
Naive T cells need co-stimulatory signals from cells with MHC class II If a T cell sees an MHC/peptide ligand without any co-stimulatory signals it becomes anergic
Ignorance?
Antigen concentration too low for TCR triggering, e.g in eye or brain
AICD?
Antigen Induced Cell Death- activation through TCR can result in apoptosis caused by expression of death Fas ligand
What transcription factor do Tregs express?
FoxP3
IL-10?
Key anti-inflammatory cytokine, down regulates macrophage functions
