Tumor Immunology

Question 1

Which components of immune system eliminate tumors

Answer 1

• macrophages and dendritic cells: MAJOR PLAYERS; direct attack/ present antigen from tumor cells
• natural killer cells: target cells w/o MHC
• CD8+/CTL: attack cells w/ MHC expression

Question 2

Antibody dependent cellular cytotoxicity

Answer 2

• antibodies prod. against surface antigens
• works well for blood cancers

Question 3

Mechanisms of tumor evasion (6)

Answer 3

• become invisible: down-regulate MHC expression & co-stimulatory signals
• appear normal: shed/limit surface expression of potential antigens
• no danger sign: release cytokines that inhibit immune cell action
• self defense: enhance T-cell death
• call riot police: attract Treg cells
• cold tumors: exclude immune cells from tumor microenvir.

Question 4

3 conditions that make cancer cells easily visible to immune cells (causes immune response)

Answer 4

• viral antigens in tumor exposed
• tumor has high mutation rate (creates neoantigens)
• tumor growth->acute inflammation

Question 5

4 ways immune system can be activated against cancer

Answer 5

• Immune Stimulation: cytokines & bacterial proteins
• Immunotoxins: antibodies against tumors
• Lymphokine activated Killers: take out lymphocytes, activate in vitro, inject back
• Checkpoint Inhibition: stimulate T-cells thru blockage of inhibitory signals

Question 6

Animal cancers that affects immune cells

Answer 6

• injection site-assc. sarcomas
• transmissible venereal tumors/sarcomas
• bovine lymphosarcoma
• marek’s disease & avian leukosis

Question 7

Injection site assc. sarcomas

Answer 7

• 1/10,000 cat vaccinations
• risk increases and # vaccines proportional
• local chronic irritation= main factor & IL-23 assc.

Question 8

Transmissible venereal tumor

Answer 8

• basically an STD for dogs
• found worldwide
• usually immune system gets rid of cells
• aggressive tumors don’t express MHC-I

Question 9

Bovine lymphosarcoma

Answer 9

• more dairy cows affected; only 5% infeted develop disease
• involved B-cells
• form of cancer is caused by retrovirus bovine leukemia; transmitted by infected lymphocytes
• immunosuppressed; low T cells

Question 10

Marek’s disease and avian lymphoid leukosis

Answer 10

• Mareks: herpes virus induced Tcell tumor; chickens; vaccine
• avian lymph. leuk.: B cell lymphoma induced by leukosis virus; no vaccine