Aberrant immune response

Question 1

How does an aberrant immune response contribute to disease?

Answer 1

An abnormal response that makes the progression worse or can cause more harm than the initial infection/ trigger.

Question 2

Describe the basic mechanisms of hypersensitivity

Answer 2

Definition: an immune response which is excessive or mounted against something it shouldn’t.
Type 1 Hypersensitivity: Stimulant causes mast cells containing irritant chemicals (e.g. histamine) to degranulate, releasing cell contents into environment
1. Some people have IgE antibodies which bind to antigenic exposures (e.g. pollen molecules)
2. IgE antibodies bind to mast cells triggering degranulation
3. Histamine and other inflammatory molecules cause local irritation
4. Secondary response: different pathway triggered for other allergens
Other types of hypersensitivity:
- Types 1, 2 and 3 are antibody mediated
- Type 4 is T cell mediated

Question 3

Describe the basic mechanisms of autoimmunity

Answer 3

A misdirected immune response that occurs when immune system goes awry and attacks the body itself. Organ vs Non-organ specific.
MECHANISM
- Genetic factors commbined with infection/ environmental exposure
- Disregulation of immune system
- Autoimmunity

Question 4

Describe the basic mechanism of transplant rejection
(4 different types)

Answer 4

4 different types of rejection:
1. Hype acute reaction: pre-formed anti-donor antibodies bind to graft endothelium immediately after transplantation
2. Acute cellular rejection: T cells destroy parenchyma and vessels by cytotoxicity and inflammatory reaction within days to months
3. Acute humoral rejection: antibodies damage graft vascilature
4. Chronic rejection: dominated by arteriosclerosis, T cell reaction and secretion of cytokines induces proliferation of vascular smooth muscle cells associated with parenchymal fibrosis.