FINAL EXAM: Immunity to Tumors Flashcards
Altered self-cells that fail to grow normally are called…?
Tumor or neoplastic cells
Benign tumor
Not capable of indefinite growth
Malignant tumor
CANCER- continues to grow and is progressively invasive
How does a metastastic tumor spread?
Via lymph or blood
Carcinoma
Malignant tumor of epithelial cells
Sarcoma
Solid tumor of connective tissue
Leukemia
Malignant tumor of of bone marrow cells that proliferate as single cells
Lymphoma
Malignant tumor of bone marrow cells that grow as tumor masses
How are tumor antigens classified?
Based on their pattern of expression
TSA
Tumor specific antigen
How are TSAs induced?
By viruses or carcinogens
FOCMA antigen
Virus-induced TSA found on neoplastic lymphoid cells of cats with Feline Leukemia Virus
Carcinogens induce ________ mutations
random
TAA
Tumor Associated Antigens
Where and when are TAA’s expressed?
Expressed on normal cells, but higher in concentration in cancer patients
How are tumor antigens (TAAs) processed, presented and recognized?
Processed as cytosolic proteins.
Presented as peptides together with class I MHC molecules on the surface of tumor cells
Recognized by CTLs as altered self-cells
What are reactivated gene products?
Products of developmental genes only expressed during embryonic development
Oncofetal genes
Cancer cells only in embryonic or fetal life that do NOT provoke protective immunity
Why are oncofetal genes clinically relevant?
Important for tumor diagnosis
AFP
Alpha-fetoprotein
What does AFP do?
It is an immunoregulatory protein found majorly in fetal serum
Where is AFP synthesized?
Yolk sac and fetal liver
When would you see elevated AFP levels?
In patients with hepatocellular carcinoma
CEA
Carcinoembryonic antigen
Where is CEA found?
Integral membrane protein found on:
gastrointestinal cells
pancreatic cells
liver cells
When is CEA found?
During the first 2 trimesters of gestation
When would you see increased levels of CEA?
In patients with carcinomas of the colon, pancreas, stomach, and breast.
What does CEA do?
It is an intercellular adhesion molecule that promotes the binding of tumor cells to one another
CEA and AFP are both what?
Oncofetal antigens
Tumor antigens induce both ______ and _____ responses that results in the killing of tumor cells.
Humoral and CMI responses
CTLs
CD8+ Cytolytic T Lymphocytes
What do CTLs do?
Kill malignant cells expressing mutant cellular proteins or oncogenic viral proteins
What is cross-priming in relation to CTLs?
The process of expressing co-stimulators that provide the 2nd signals needed for differentiation of CD8+ T cells into antitumor CTLs
Do effector CTLs need co-stimulation in order to recognize and kill tumor cells?
NO
What do NK (natural killer) cells do?
Kill tumor cells that have reduced class 1 MHC expression
What receptor is commonly found on NK cells?
FcyRIII [CD16]
What does the FcyRIII [CD16] receptor on NK cells do?
Binds to IgG coated tumor cells leading to ADCC
What receptors are found on macrophages that allow them to bind to IgG coated tumor cells and mediate ADCC?
Fcy receptors
When macrophages kill tumor cells, what is released?
Nitric Oxide and cytokine TNF-a.
What does TNF-a do to tumors when secreted by activated macrophages?
Causes hemorrhage and necrosis of the tumor
How do antibodies kill tumor cells?
By activating complement or by ADCC with NK cells and macrophages
How do tumors evade immune responses?
By failing to produce tumor antigen, not expressing Class 1 MHC molecules, lack of co-stimulation, immunosuppresion or antigen masking. This causes T- cells to not be able to recognize the tumor cell.
How do tumors achieve antigen-masking?
By increasing their expression of of cell surface glycocalyx molecules
What are some methods of tumor immunotherapy?
Cytokine therapy Tumor Necrosis Factor Interferons Adoptive Cellular Therapy Monoclonal antibodies Tumor Vaccines
