Abberrant Immune Response Flashcards
What is type 1 hypersensitivity?
When the immune response mounts reaction too vigorously and unnecessarily.
What are examples of type 1 hypersensitvity?
Allergy to pets, foodstuffs, flowers, latex
What molecules are the main culprits of type 1 hypersensitivity?
Mast cells
IgE
On a molecular level, what happens in type 1 hypersensitivity?
IgE binds to surface receptors of mast cell and when antigen binds to IgE, signal is sent into the cell causing degranulation, releasing granule contents histamine and vasoactive amines instantly.
Later on, mast cells will produce new and release further inflammatory molecules eg. leukotrienes, prostaglandins
Which types of hypersensitivity are antibody mediated?
Type 1
Type 2
Type 3
Which types of hypersensitivity are cell mediated?
Type 4
What is autoimmunity?
A misdirected immune response that occurs when the immune system goes awry and attacks the body itself.
What is organ specific autoimmunity and what are some examples of conditions that show this?
-When there is autoimmune attack vs. self-antigens of given organ
-Causes damage to organ structure and function
Eg. Type 1 diabetes, Goodpastures Syndrome
What is non-organ specific autoimmunity and what are some examples of condtitions that show this?
-When widespread self-antigens are targets for autoimmune attack
-Damage will affect such structures as blood vessels, cell nuclei etc.
Eg. Rheumatoid arthritis
How does autoimmune response cause rheumatoid arthritis?
-Caused by immune system fighting own tissues of joints
How does autoimmune response cause graves disease?
- Normally pituatary gland releases TSH that binds to receptor and stimulates cell in thyroid to produce hormones.
- This works by a negative feedback loop, so will stop TSH production when there is enough.
- In this disease, antibodies are created that mimick TSH binding, leading to overstimulation of thyroid cell, so hormones are overproduced.
How does autoimmune response cause type 1 diabetes?
- Normal islets of langerhans contain several cell types secretingdistinct hormones. Each cell expresses different tissue-specific proteins.
- In insulin dependant diabetes an effector T cell recognizes peptides from a Beta cell specific protein and kills the Beta cell, so insulin wont be made.
- Glucagon and somtostatin are still produced but insulin cant be made.
Why are transplants rejected?
Body sees transplanted organ as foreign, so will mount immune response to it.
Which cells respond to donor organs?
T cells are activated against donor transplantation antigens, leading to stimulation in peripheral lymphoid tissues.
CD4, CD8, macrophage, DC’s, neutrophils, B cells, NK cells, antibodies and complements.
What are the types and mechanisms of rejection?
- Hyperacute
- Acute cellular
- Acute humoral
- Chronic rejection
