Definition: Damage to host tissue caused by an immune response which cannot be directly attributed to
an infection process
Introduction
● Organ specific or systemic
● Approximately 40 [known] diseases, affects 5% of population
● Autoantibody generation (inappropriate TH2 response, humoral) or mononuclear cell invasion
(inappropriate TH1 response, cell mediated)
Proposed Mechanisms
● Cause of loss of self-tolerance is unknown. More research needed for identification of target self
antigens and why autoantibodies can also be found in healthy individuals
● Cryptic antigen response
○ Antigen causing autoimmune response is usually hidden until cell bursts/damaged etc.
● Sequestered antigen release
○ viral/physical damage causes cell to burst open and release contents → an
otherwise concealed peptide is exposed
● bacterial/viral mimicry & cross reaction
○ bacterial/viral antigen recognised by the immune system and creates antibodies. If
recognised antigen is very similar in shape to a self antigen then can cause an autoimmune
response
● Undiscovered pathogen causing immune
Cytoplasmic islet cell antibody (ICA)
response
● Abnormal immunoregulation
○ Fault with T cells
HUMORAL
Anti-insulin antibody prevents insulin
● Polyclonal activator production
○ Superantigens bind to non-matching
binding site
● Anti-idiopathic networks Anti-GAD antibody destroys any insulin
produced
○ Antibodies bind to one another to
activate one another. Over reaction?
TH1 cytokine profile
● Latent viral infection
○ If virus stays dormant in cell for too lo ,ng
it may change self antigen binding site(s) Mononuclear cell infiltration
CELLULAR
(macrophages) decrease of antibody
activity
Multifactorial Influences
● Interaction of many risk factors
● Specific interactions and environmental factors Tc and/or NK cells causes cell apoptosis
Genetic Predisposition
● Could link to many chromosomal loci → Specific targeting of B cells induction of cell
more susceptible or resistant? apoptosis
● MHC class I and II haplotypes inherited and can
determine relative risk
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