When The Immune System Goes Wrong Flashcards
What is immune system hypersensitivity?
An immune response to a harmless molecule, such as with allergens.
Explain the stages of immune hypersensitivity of a an allergenic response.
1) allergen is taken up by antigen presenting cells and displayed on MHC2 receptors
2) CD4 T-cells bind to this complex and via the signal of IL4 differentiate into Th2 T-helper cells which release cytokines IL2, 4, 5 and 13.
3) these released cytokines aid B-cell class switching to Ige and help them differentiate into Ige secreting plasma cells.
4) this Ige binds to mast cells on muscosal surfaces
5) when pollen arrives on these sites it binds to multiple Ige sites which causes mast cell degranulation, histamine release and the relevant signs and symptoms associated with allergy.
What is the name of the process by which small doses of allergens are given to patients over a number of years to promote a reduction in sensitivity to the allergens?
Desensitisation.
What is autominnunity?
A loss or immunological tolerance to self components as in health we have a controlled failure to respond to self despite having the capacity to do so.
Name an organ specific autoimmune disease.
Type 1 diabetes (loss of pancreatic beta cell function)
Grave’s disease (increased function of the thyroid gland)
What are autoantibodies?
Antobodies produces in response to self.
How is Graves’ disease caused?
Autoantibodies bind to thyrocytes which make continuous thyroxine.
How does myasthenia gravis work?
Autoantibodies bind to ach at neuromuscular junctions and destroy them. They decrease in number and the result is that for the same level of stimulus a much reduced response is seen in muscle contraction.
How can affected mothers with graves or myasthenia gravis pass this onto their offspring?
Maternal Igg is transported to the child to protect it within the first weeks of life until it can produce its own antibodies, meaning the pathology can be passed on.
What causes rheumatoid arthritis?
T-cells, NOT autoantibodies!
What causes type 1 diabetes?
T-cells, NOT autoantibodies.
What is di-George syndrome?
A lack of thymus developing means no T-cells are produced.
