T-cell Mediated Tumor Response

Question 1

What is a tumor antigen?

Answer 1

Molecules expressed by tumor cells that are not expressed in healthy cells.

Question 2

What are the 3 general types of tumor antigens?

Answer 2

1. Products of oncogene or mutated tumor suppressor gene.
2. Overexpressed self protein
3. Oncogenic virus particles.

Question 3

Discuss the T-cell mediated response against tumors.

Answer 3

1. Tumor antigen shown to DC
2. Dendritic cells phagocytose the tumor cell.
3. Cross-presentation (MHC 1 and 2)
4. Activates tumor specific CD8 and CD4(Th1)

Question 4

Discuss the B-cell mediated response against tumors.

Answer 4

Production of anti-tumor antibodies

1. Opsonization
2. Activate NK cells
3. Activate complement
4. Block receptors on tumor cells needed for survival/growth

Question 5

What are the 5 ways tumor cells evade the immune system?

Answer 5

1. Change the antigen the immune system is responding to.
2. Downregulate MHC 1
3. Secrete IL-10 & TGF-B (Supresses Th1 and attracts Tregs)
4. Express CTLA-4 to inhibit co-stimulation
5. Express Fas ligand

Question 6

Discuss monoclonal antibody treatment.

Answer 6

Tumor antigen specific T cells are removed from patient and expanded in vitro. Re-introduced to patient. Downside is there is no memory.