Hypersensitivities IV

Question 1

Explain the indirect effector phase

Answer 1

Sensitised CD4 cells encounter an antigen
* produce cytokines + chemokines
* Activate macrophages, monocytes, neutrophils …
* tissue damage

Question 2

Explain the direct effector phase

Answer 2

• Mediated by cytotoxic cells
• sensitised T cells encounter an antigen associated with MHC I
• perforins and granzymes produced by CD8 + T cells cause apoptosis
• cytokines produced by the CD8 cell also cause inflammation

Question 3

What do the chronic responses produce?

Answer 3

granulomatous inflammation

Question 4

What can granulomatous inflammation cause over time?

Answer 4

granulomas (nodules)

Question 5

What is the tuberculin test?

Answer 5

Test to evaluate exposure to Mycobacteria species
* if the animal has been sensitised a swollen nodule of oedema and perivascular mononuclear cells occurs (due to memory T cells attracting other immune cells to the site if there was previous infection)

Question 6

How does allergic contact hypersensitivity occur?

Answer 6

Antigens are often too small to cause an immune response on their own
they can complex with larger proteins in the skin to trigger an immune response
repeated exposure results in inflammation and dermal vesicles