Immunology - Autoimmunity Flashcards
What is imunological tolerance?
Unresponsiveness to an antigen that is induced by previous exposure to that antigen
what are antigens that induce tolerance called?
Tolerogens
What are tolerogens?
Antigens that induce tolerance
What controls central tolerance?
Thymus eliminates T cells with high affinity to self antigens
Bone marrow for B cell tolerance
What controls peripheral tolerance?
Mature lymphocytes that recognize self antigens in peripheral tissues become incapable of activation or die by apoptosis
Mechanisms of peripheral tolerance
Anergy (functional unresponsiveness)
Antigen recognition without co-stimulation
Treg Suppression
Deletion (cell death)
Some self antigens are sequestered from the immune system by anatomical barriers
What can result in peripheral tolerance being overcome?
Inappropriate access of self-antigens
Inappropriate or increased local expression of co-stimulatory molecules
Alterations in the ways in which self-molecules are presented to the immune system
When does autoimmune disease occur?
When autoreactive T cells or autoantibodies cause tissue damage through hypersensitivity reaction types II, III and IV
Which cells are the major source of autoantibodies?
B1 cells
What are the environmental factors that can influence autoimmunity?
Infections -Molecular mimicry -Upregulation of co-stimulation -Antigen breakdown and presentation changes Drugs -Molecular mimicry -Genetic variation in drug metabolism UV radiation -Trigger for skin inflammation -Modification of self-antigen
What is molecular mimicry?
Structural similarity between self-proteins and microbial antigens that may trigger an autoimmune response
Non-organ specific autoimmune diseases
Affect multiple organs
Associated with autoimmune responses against self-molecules which are widely distributed throughout the body
Intracellular molecules involved in transcription and translation
Organ specific autoimmune diseases
Restricted to one organ
Endocrine glands
Treatment of autoimmune diseases
Suppression of the damaging immune response
Replacement of the function of the damaged organ
What is autoimmunity?
An immune response against a self antigen
