Summary: Physiology: Immunological Pathologies

Read the summary and the most important questions on Physiology: Immunological Pathologies

• 3 Lecture 26: Autoimmunity

• 3.1.1 Type I hypersensitivity in cows

• How does Type I hypersensitivity in cows occur?

  When milking is delayed, intramammary pressures can cause milk to enter circulation and cause immune responses. 
  
  If immune response has a Th2 bias, it can promote the development of IgE = milk allergy
  
  Can lead to anaphylaxis

• 3.1.2 How does autoimmunity develop?

• How does self tolerance get lost in autoimmunity?

  1. Breakdown of tolerance: failure of central and peripheral tolerance
     
  2. Genetic susceptibility: inherited genes with MHC
  3. Environmental triggers: molecular mimicry 
  4. Immune dysregulation: Imbalance between effector and regulatory cells leading to chronic inflammation
  5. Tissue damage and disease: epitope spreading and sustaining autoimmune response

• What are hidden antigens in autoimmunity?

  Self proteins that are normally concealed from immune system due to anatomical barriers, may be exposed via barrier opening.

• 3.1.3 Molecular mimicry

• What is molecular mimicry?

  When foreign antigens share structural similarities with self-antigens leading the immune system to mistakenly attack self tissues. (e.g. Viruses)

• 3.1.5 Autoantibody development

• How do cross reactions happen?

  Foreign antigens can trigger Th cell activation, and can lead to Th cell aiding a B cell that has reacted to self epitopes, leading to creation of autoantibodies

• 3.1.6 Microchimerism

• How does microchimerism occur for autoimmunity?

  Fetal cells enter maternal circulation and vice versa -> microchimerism
  - Fetus develops tolerance as immune system is being educated
  - Mother's immune system may react to fetal cells and cause autoimmunity (via cross-reaction)

• 3.1.7 Predispositions to autoimmunity

• What are some genetic predispositions for autoimmunity?

  MHC polymorphism with some MHC alleles being highly associated with autoimmunity from long-term selective breeding

• 5 Lecture 28: Immunodeficiencies

• 5.2 Primary immunodeficiency

• What is primary immunodeficiency?

  It is when genetic defects cause immune system to lack the ability to fight off infections/cancer

• What can cause primary immunodeficiency?

  Reduced heterozygosity in immune cell genes, especially in highly inbred organisms. Nature and severity of disease depends on where defect occurs during immune system development

• 5.2.1 Chediak Higashi Syndrome

• What is Chediak Higashi syndrome?

  It is the impaired function of phagosomes with lysosomes, lysosomes in cytotoxic T cells and NK cells fail to degranulate.