18: Tumor Immunology Flashcards
Tumor
Mass of cells that results from abnormal multiplication of host cells
Metastasis
Spreading of cancer cells through the lymph or bloodstream to distant parts of the body other than the original site
When a cell has become able to form a cancer, it is said to have undergone __________.
Malignant transformation
Proto-oncogenes
Genes that normally contribute positively to the initiation and execution of cell division
Oncogenes
Mutant forms of proto-oncogenes that contribute to malignant transformation
Mutagens
A chemical or physical agent that increases mutation rate
Cancer arises from ___________.
A single cell that has accumulated multiple mutations in genes that are involved in cell multiplication and cell survival
What are the two types of genes that can be mutated or mis-expressed to contribute to malignant transformation?
- Proto-oncogenes: normally function in initiation or execution of cell division
- .Tumor suppressor genes: normally function to prevent unwanted proliferation oc cells
How many mutations must a cell acquire for it to become a cancer cell?
5-6 ish mutations
What demographic does cancer affect most?
Elderly, because incidence of cancer increases with age
Any mutagen that increases the risk of cancer is known as _________.
A carcinogen
What kind of mutations do chemical carcinogens typically give rise to?
Single base change mutations
What typically induces more pronounced mutations such as DNA breaks, cross-linked nucleotides, and abnormal recombination?
Radiation
What is a carcinoma?
Cancer of epithelial cells
What is a sarcoma?
Cancer of cells other than epithelial cells
Leukemias involve _______.
Circulating cells
Lymphomas involve ________.
Solid lymphoid tumors
Myelomas involve _________.
Bone marrow
How can viruses cause the development of cancer cells?
- Oncoviruses infect cells and express virally encoded proteins that can override the cell’s normal mechanisms for regulating cell division
- Some viruses prevent the normal tumor suppression mechanisms of infected cells from operating, which gives rise to abnormally proliferating cells
Some tumors express “tumor-specific” antigens that can be recognized and killed by _________.
Allogeneic CD8 T cells
T or F: Most cancers are eliminated by the immune system.
F: because the immune system can’t recognize tumors as non-self
What’s the difference between tumor-specific antigens and tumor-associated antigens?
Tumor-specific are on tumor cells but not normal cells, and tumor-associated are found on both
What are the most common tumor antigens?
Peptides bound to MHC Class I molecules recognized by CD8+ T cells
T or F: Tumors have surface determinants that can be recognized by antibody molecules and B cell receptors.
T
How was protective immunity to tumors demonstrated?
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)
Typically between 1/3 and 1/2 of the cells in a tumor have defects in expression of ________.
One or more of their HLA molecules (MHC class I molecules)
T or F: CTLs and NK cells are both involved in immunity to tumors.
T
How can tumor cells that don’t express MHC class I be killed?
They can’t be recognized by effector CTLs, but they can be killed by NK cells.
T or F: All tumor cells are susceptible to NK cell mediated killing
F: only cells that are devoid of the production of each of the MHC class I alleles
What can form a zone of immunosuppression around the border of a tumor?
Tumors can produce cytokines such as TGF-beta to suppress or mis-direct immune responses
What can tumor-specific monoclonal antibodies be used for?
- Can be used to detect tumors
- 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)
How can T cells be used for immunotherapy of cancer?
T cells specific for tumor antigens can be grown in vitro then injected back into the patient
What will happen in the recombinant DNA approach to cancer treatment?
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
