18: Tumor Immunology

Question 1

Tumor

Answer 1

Mass of cells that results from abnormal multiplication of host cells

Question 2

Metastasis

Answer 2

Spreading of cancer cells through the lymph or bloodstream to distant parts of the body other than the original site

Question 3

When a cell has become able to form a cancer, it is said to have undergone __________.

Answer 3

Malignant transformation

Question 4

Proto-oncogenes

Answer 4

Genes that normally contribute positively to the initiation and execution of cell division

Question 5

Oncogenes

Answer 5

Mutant forms of proto-oncogenes that contribute to malignant transformation

Question 6

Mutagens

Answer 6

A chemical or physical agent that increases mutation rate

Question 7

Cancer arises from ___________.

Answer 7

A single cell that has accumulated multiple mutations in genes that are involved in cell multiplication and cell survival

Question 8

What are the two types of genes that can be mutated or mis-expressed to contribute to malignant transformation?

Answer 8

1. Proto-oncogenes: normally function in initiation or execution of cell division
2. .Tumor suppressor genes: normally function to prevent unwanted proliferation oc cells

Question 9

How many mutations must a cell acquire for it to become a cancer cell?

Answer 9

5-6 ish mutations

Question 10

What demographic does cancer affect most?

Answer 10

Elderly, because incidence of cancer increases with age

Question 11

Any mutagen that increases the risk of cancer is known as _________.

Answer 11

A carcinogen

Question 12

What kind of mutations do chemical carcinogens typically give rise to?

Answer 12

Single base change mutations

Question 13

What typically induces more pronounced mutations such as DNA breaks, cross-linked nucleotides, and abnormal recombination?

Answer 13

Radiation

Question 14

What is a carcinoma?

Answer 14

Cancer of epithelial cells

Question 15

What is a sarcoma?

Answer 15

Cancer of cells other than epithelial cells

Question 16

Leukemias involve _______.

Answer 16

Circulating cells

Question 17

Lymphomas involve ________.

Answer 17

Solid lymphoid tumors

Question 18

Myelomas involve _________.

Answer 18

Bone marrow

Question 19

How can viruses cause the development of cancer cells?

Answer 19

1. Oncoviruses infect cells and express virally encoded proteins that can override the cell’s normal mechanisms for regulating cell division
2. Some viruses prevent the normal tumor suppression mechanisms of infected cells from operating, which gives rise to abnormally proliferating cells

Question 20

Some tumors express “tumor-specific” antigens that can be recognized and killed by _________.

Answer 20

Allogeneic CD8 T cells

Question 21

T or F: Most cancers are eliminated by the immune system.

Answer 21

F: because the immune system can’t recognize tumors as non-self

Question 22

What’s the difference between tumor-specific antigens and tumor-associated antigens?

Answer 22

Tumor-specific are on tumor cells but not normal cells, and tumor-associated are found on both

Question 23

What are the most common tumor antigens?

Answer 23

Peptides bound to MHC Class I molecules recognized by CD8+ T cells

Question 24

T or F: Tumors have surface determinants that can be recognized by antibody molecules and B cell receptors.

Answer 24

T

Question 25

How was protective immunity to tumors demonstrated?

Answer 25

1.Mice are immunized with irradiated tumor cells 2. An anti-tumor immune response is produced that can prevent subsequent transfer of live tumor cells of the same type (So we know that the immune system can kill tumor cells if a tumor-specific immune response can be generated)

Question 26

Typically between 1/3 and 1/2 of the cells in a tumor have defects in expression of ________.

Answer 26

One or more of their HLA molecules (MHC class I molecules)

Question 27

T or F: CTLs and NK cells are both involved in immunity to tumors.

Answer 27

T

Question 28

How can tumor cells that don't express MHC class I be killed?

Answer 28

They can't be recognized by effector CTLs, but they can be killed by NK cells.

Question 29

T or F: All tumor cells are susceptible to NK cell mediated killing

Answer 29

F: only cells that are devoid of the production of each of the MHC class I alleles

Question 30

What can form a zone of immunosuppression around the border of a tumor?

Answer 30

Tumors can produce cytokines such as TGF-beta to suppress or mis-direct immune responses

Question 31

What can tumor-specific monoclonal antibodies be used for?

Answer 31

1. Can be used to detect tumors 2. Can be used to target tumor cells for destruction (inject mAbs conjugated to toxins to poison the cell or inject mAbs conjugated to radionuclides so that the cell will be irradiated and unable to replicate)

Question 32

How can T cells be used for immunotherapy of cancer?

Answer 32

T cells specific for tumor antigens can be grown in vitro then injected back into the patient

Question 33

What will happen in the recombinant DNA approach to cancer treatment?

Answer 33

Transfect tumor cells with cytokines or chemokines that stimulate or chemoattract dendritic cells to the tumor, which facilitates uptake of tumor-specific antigens to naive T cells