Immunology 5

Question 1

Apoptosis vs Necrosis

Answer 1

Apoptosis - Natural process, cell removed without any inflammatory response. ex. skin between fingers! (Cytotoxic T cells and Natural Killer cells kill by apoptosis)
Necrosis - causes release of intracellular content and leads to inflammation.

Question 2

Activating CD8 cells

Answer 2

Can be activated either by Dendritic cells expressing a lot of B7, OR if T-helper cell and CD8 cell bind to APC at same time can use co-stimulation to activate each other.

Question 3

How do Cytotoxic T cells kill?

Answer 3

By using Perforin and Granzymes (fragmentins). CD8 cell attaches to cell, then secretes perforin which forms small pores. Granzymes then go into cell and initiates program to apoptosis!
In addition… can also kill by secreting lymphotoxin which simply kills cells.
Or by expressing FaS ligand which binds to FaS receptor on target cells, this then like granzymes initiates apoptosis in the cell.

Question 4

Natural Killer Cells

Answer 4

NK cells. Part of innate immune response. Kill by 2 ways. First way… by MHC I.. if MHC I is present cell sends signal which inhibits NK from killing. If MHC I is not present or is present in an abnormal level this signal cannot be sent and NK cell kills by releasing granules to start apoptosis. Second can recognize a self protein induced on a tumour cell. Can also kill by ADCC!