Autoimmunity Flashcards
What is autoimmunity?
Immune response against the host due to the loss of immunological tolerance of self-antigen(s)
What is an autoimmune disease?
Disease caused by tissue damage or disturbed physiological responses due to an auto-immune response
What is criteria for the diagnosis of a disease as autoimmune?
- Presence of autoantibodies/autoreactive T cells
- Levels of autoantibodies correlate with disease severity
- Autoantibodies/autoreactive T cells found at the site of tissue damage
- Transfer of auto-antibody or autoreactive T cells to a healthy host induces the autoimmune disease
- Clinical benefit provided by immunomodulatory therapy
- Family history
What triggers autoimmunity?
- Genetic Factors
- Environmental Factors
What are genetic factors for triggering autoimmunity?
- Increased risk with an affected Sibling
- Increased risk with an affected identical twin
- AIRE mutations that affect central tolerance
- Autoimmune disease associated with MHC variants
What are environmental factors for triggering autoimmunity?
- Hormones
- Infections
- Drugs
What are diseases caused movement of IgG from mother to foetus during pregnancy? (transitionary autoimmune disease)
- IgG can bind to TSH receptor to cause Neonatal Graves’ Disease by activating the receptor
- IgG can bind to Platelet to cause Thrombocytopenia by causing cell lysis
- IgG can bind to Red Blood Cells to cause Haemolytic Anaemia by cause cell lysis
- IgG can bind Acetylcholine Receptor to cause Neonatal Myasthenia Gravis by causing receptor blockade
What infectious diseases can trigger autoimmune diseases?
- Streptococcus pyogenes produce M protein.
- It has similar structure to the antigen in cardiac muscle. Body produces antibodies that cross-react; causing Rheumatic fever with damage to heart (in particular heart valves).
What are strategies for therapy?
- Autoantibodies: Plasma exchange
- Autoreactive T cells: Immunosuppressive drugs
- Tissue Damage: Anti-inflammatory Drugs
- Organ dysfunction: Replacement therapy or Surgery
What are mechanism for induction of autoimmunity?
- Breakdown of central tolerance
- Breakdown of peripheral tolerance
- Activation of autoreactive B cells
What are mechanisms involved in breakdown of central tolerance?
-Failure to delete Autoreactive T cells
What is involved in breakdown of Peripheral tolerance?
- Regulatory T cells (Treg) defects
- Impaired immunomodulation
- Altered self-antigens
What is involved in activation of autoreactive B cells?
- T cell-independent activation of B cells
- Carrier effect (complex foreign-self antigens
