Flashcards in Autoimmunity Deck (11):
Immune response against the host due to loss of immunological tolerance of self-antigens
Define autoimmune disease
Disease caused by tissue damage/disturbed physiological responses to an autoimmune response
What are the criteria for a disease to be considered 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 autoantibodies/autoreactive T cells to healthy host induces autoimmune disease
Clinical benefit from immunomodulatory therapy
How does tissue damage occur in autoimmunity?
Autoantibodies - complement activation, antibody mediated cell cytotoxicity, neutrophil activation
Autoreactive T cells - Cytotoxic T cells, macrophages
Explain how infection can lead to autoimmunity
Streptococcus pyogenes produces an antigen that is similar to cardiac muscle antigen, body produces antibodies that cross react causing rheumatic fever that damages the heart
Which drugs can induce autoimmunity?
Methyl-dopa (antihypertensive) - haemolytic anaemia
Procainamide (antiarrythmic) - SLE
Describe the endogenous ways that autoimmunity can be induced
Failure to delete autoreactive T cells - breakdown of central tolerance
Altered self antigens and T cell defects - breakdown of peripheral tolerance
Independent activation of B cells (without T cells) - activation of autoreactive B cells
What are the strategies for treating autoimmune diseases?
Monoclonal antibodies (Infliximab)
How does neonatal myasthenia gravis occur?
Maternal IgG antibody to acetylcholine receptor causes a receptor blockade, causing skeletal muscle weakness
How does neonatal Grave's disease occur?
Maternal IgG antibody to thyroid stimulating hormone causes activation of the fetus' TSH receptors, causing hyperthyroidism