Autoimmunity Flashcards
What is immunological tolerance?
Unresponsiveness to an antigen that is induced by previous exposure to that antigen
What is the name of antigens which induce tolerance?
Tolerogens
What is self tolerance?
Tolerance to self-antigens
What is the general cause of autoimmunity?
Failure of self-tolerance
How is self-tolerance regulated?
T and B cells bearing self reactive molecules are destroyed
During development T cells are regulated in thymus and B cells in bone marrow (central tolerance)
Self reactive mature cells in periphery become incapable of activation or die of apoptosis (peripheral tolerance)
What are different mechanisms of peripheral tolerance?
Anergy (functional unresponsiveness)
Antigen recognition without co-stimulation
T-reg suppression
Deletion (cell death)
Some self antigens are sequestered from the immune system by anatomic barriers
What can cause autoimmune cells to overcome peripheral tolerance?
Inappropriate access of self antigens
Inappropriate or increased local expression of co-stimulatory molecules
Alterations in the ways in which self antigens are presented to the immune system
What is epitope spreading?
Immune response broadening and accelerating tissue damage due to inflammatory response - once tolerance is overcome autoimmunity may be easier to sustain
What factors can lead to a breakdown of tolerance?
Genetics
Infections
Environmental factors
What is autoimmunity?
Adaptive immune response to self antigens
What are autoantibodies?
Antibodies directed at normal cellular components, referred to as autoantigens
What is the main source of autoantibodies?
Natural antibodies secreted by B1 cells
What are examples of autoimmune diseases?
Ankylosing spondylitis Reiter disease Sicca syndrome Addison disease Hashimoto thyroiditis Myasthenia gravis Insulin dependent diabetes mellitus (type 1)
What gene is commonly affected in autoimmune disease?
AIRE gene
Are autoimmune disease more common in men or women?
Women except ankylosing spondylitis
