Tumor Immunity

Question 1

What are tumor-specific antigens?

Answer 1

Antigens that are unique to cancer cells

Question 2

What are the two types of TSAs?

Answer 2

1. Virus-induced: cross-reactive; immunotherapy should apply to all people infected by the same virus
2. Chemical/physical carcinogen-induced: random mutations in affected cells; each Ag differs and immunological cross-protection is not feasible

Question 3

What are tumor-associated antigens?

Answer 3

Antigens not found exclusively on cancer cells

Question 4

What are the two types of TAAs?

Answer 4

1. Oncofetal Ag / Carcinoembryonic antigen (CEA): high concentrations typically disappear at birth and reappear with colorectal cancer
2. Oncofetal Ag / alpha-Fetoprotein: high levels in fetal and maternal serum; low levels in typical adults

Question 5

What is an example of a virus-induced TSA?

Answer 5

Antigens associated with HPV, EBV, etc

Question 6

What is an example of carcinogen-induced TSA?

Answer 6

Cancer antigens arising from smoking, etc

Question 7

What is an example of a CEA?

Answer 7

Colorectal cancer antigen

Question 8

What is an example of an alpha-Fetoprotein?

Answer 8

Liver cancer antigen

Question 9

What is ADCC?

Answer 9

Antibody-Dependent Cell-Mediated Cytotoxicity

Fc receptor-bearing macrophages or NK cells mediate killing

Question 10

What cytokines stimulate macrophages and NK cells?

Answer 10

IL-12
IL-15
IFN-gamma

Question 11

What are the mechanisms by which tumors evade immune response?

Answer 11

1. Losing expression of Ags
2. Downregulating MHC-I
3. Producing immuno-suppressive molecules (inhibit T cell activation) –> TGF-B, PD-L1
4. Tumor arising in immunologically privileged site

Question 12

What are M1 and M2?

Answer 12

Macrophages

M1: classically activated, inhibits tumor growth via TNF
M2: tumor associated; alters tissue microenvironment and suppresses T cell response