Autoimmunity Flashcards
What is autoimmunity?
Adaptive immune response to self-antigens and tissues
What are tolerogens?
Antigens which induce tolerance
What are the 2 levels of immunological tolerance?
Central
Peripheral
What happens when T and B cells bearing self-reactive molecules?
Eliminated or downregulated to stop them being too active against self antigens
What role does the thymus play in central tolerance?
Important in eliminating T cells with high affinity for self-antigens
What role does bone marrow play in central tolerance?
Important for B cell tolerance
What is tolerance?
Unresponsiveness to an antigen that is induced by previous exposure to that antigen
What happens to mature lymphocytes in peripheral tissue with high affinity to self antigens?
Become incapable of activation or die by apoptosis
What is co-stimulation?
T cells require co-stimulation to become active
If T cells react with tissues which express self-antigens then there is no co-stimulation
What are the different mechanisms of peripheral tolerance?
Anergy
Regulatory T cell suppression
Deletion (cell death)
Some self antigens are sequestered from the immune system by anatomic barriers
What is anergy?
Antigen recognition without co-stimulation
How may peripheral tolerance be overcome?
Inappropriate access of self-antigens
Inappropriate local expression of co-stimulatory molecules
Alterations in the ways in which self-molecules are presented to immune system
What are risk factors for compromised peripheral tolerance?
Inflammation or tissue damage Successive infection UV light Drugs Proteolytic enzymes increase peptide concentration of peptides presented to active T cells
What cell type produce natural antibodies?
B1
What causes breakdown of T cell tolerance?
Genetic predisposition
Environmental factors
