Tolerance and Autoimmunity Flashcards
What type of immune response is involved in autoimmunity?
Adaptive immune response
Which cell type is always involved in autoimmunity?
Lymphocytes
What proportion of people has lymphocytes with the capability of recognising self-antigens?
ALL of us – this is normal autoimmunity
What are the three main factors that affect the transition from normal autoimmunity to autoimmune disease?
Genetic susceptibility
Infections
Environmental factors
Why are autoimmune conditions chronic?
Because self-tissue is always present
The effector mechanisms in autoimmunity resemble those of which type of immune reaction?
Hypersensitivity reactions (types 2, 3 and 4)
What proportion of people affected by autoimmune disease isfemale?
75% overall (this changes between diseases)
What is a possible reason for the increase in incidence of autoimmune disease?
Hygiene hypothesis
Describe the pathophysiology of autoimmune haemolytic anaemia.
There are autoantibodies against red blood cells, which bind to red blood cells and activate complement
This results in clearance and complement-mediated lysis of the autologous erythrocytes
What is a type II hypersensitivity reaction?
Antibody response against cellular or ECM antigens (insoluble antigens)
What is a type III hypersensitivity reaction?
Immune complex formation by antibody against soluble antigen
What is a type IV hypersensitivity reaction?
T cell mediated disease – delayed type hypersensitivity
What is Goodpasture’s syndrome?
Type 2 hypersensitivity reaction in which there are IgG antibodies against a type IV collagen found on the basement membrane in the glomerulus
This results in deposition of autoantibodies in the renal corpuscle and activation of complement leading to infiltration of inflammatory cells and kidney damage
NOTE: the inflammatory cells (e.g. neutrophils) bind to the Fc portion of antibodies via their own Fc receptors
How do type II and type III immune reactions recruit inflammatory cells?
Inflammatory cells are recruited via the binding of inflammatory cells to the Fc portion of antibodies via their Fc receptors
What is the main difference between type II and type III hypersensitivity reactions?
Type II – insoluble antigens
Type III – soluble antigens