IAI - when immune system goes wrong Flashcards
What is immediate hypersensitivity?
Allergy
Mediated by IgE, mast cells and Th2 responses
What is atopy?
an inherited tendency to make immediate hypersensitivity responses
What is the immediate hypersensitivity response due to?
Due to mast cell
degranulation and histamine release and when it happens in the skin there is a wheal and flare.
- Wheal = raised lesion
- Flare = surrounding redness
What is the Th2 response to allergy?
What are serum autoantibodies?
- Usually IgG class
- Important diagnostic tools
- Useful for monitoring disease activity
- Useful for predicting future disease
- May be pathogenic (ie cause disease)
Describe Graves’ disease.
It is an autoimmune thyroid disease.
How is homeostasis of the thyroid gland and production of thyroxine is maintained in a healthy person?
- Production of thyroxine by the thyroid gland is regulated by thyroid stimulating hormone (TSH) produced by pituitary gland.
- Binding of TSH to the TSH receptor stimulates the production of thyroxine.
- Negative feedback by throxine prevents excess TSH production by the pituitary gland.
What occurs in Graves’ disease causing homeostasis of the thyroid gland to be unregulated?
- An autoantibody is produced which binds to the anti-TSH receptor on the thyrocyte and maintains it on the on position.
- The thyroid gland keeps making thyroxine in a completely unregulated way which leads to the symptoms of hyperthyroidism.
- As a result there is constant stimulation of the thyroid and pituitary with no feedback loop.
- Patients can therefore experience a fast heartbeat, hyperactivity, weight loss, bulging eyes and a neck goitre.
What is myasthenia gravis?
Myasthenia gravis is impaired connection across the neuromuscular junction. This is due to patients developing autoantibodies to the acetylcholine receptor. These lead to damage and a number of receptors on the muscle side are reduced. = muscular weakness and fatigue.
What occurs in the last trimester of pregnancy?
Maternal IgG is transported across the placenta to protect the baby during the first weeks of life until the baby’s own antibody response develops.
How does neonatal Graves’ disease occur?
Mother with Grave’s disease has IgG autoantibodies to thyroid stimulating hormone (TSH) receptor.
cross placental transfer of igG in the last trimester
How does type 1 diabetes occur?
Type 1 diabetes is also an autoimmune disease - it is a progressive loss of the insulin producing beta cells of the pancreas resulting in failure to regulate blood sugar levels.
what mediates type 1 diabetes
type 1 diabetes is T cell mediated.
How is type 1 diabetes T cell mediated?
- CD8 T cell mediated killing of Beta cells
- CD4 T cell mediated inflammation
- Failure of Treg to suppress
What categories are immunodeficiency split into?
- PRIMARY = inherited defect = rare
- SECONDARY = acquired defect = common