13 Flashcards
What is tumor immunology?
The immune system can detect and destroy abnormal cells, including tumors. But sometimes, tumors find ways to grow despite immune defenses
Define tumor antigens.
Abnormal or unusually expressed molecules on cancer cells that can be targeted by the immune system
What are neoantigens?
Tumor cell mutations that generate neoepitopes recognized as foreign by T cells -immune response
How do virus-induced tumor cells affect T cell response?
They show viral peptides that trigger a T cell response
What are overexpressed cellular proteins?
Proteins that are normally low or off in healthy cells but are overexpressed in cancer
HER2/NEU: Overexpressed in some breast cancers.
Cancer/testes antigens: Normally only active in testes, now in tumors.
Give an example of an overexpressed protein in cancer.
HER2/NEU in some breast cancers
What are oncofetal antigens?
Antigens normally present only in fetal development, but return in tumors
List two examples of oncofetal antigens.
- CEA (carcinoembryonic antigen)
- AFP (alpha-fetoprotein)
What are altered glycoproteins and glycolipids?
Molecules like MUC1 that are abnormally presented in cancers, triggering immune responses
MUC1: Normally hidden from the immune system in breast tissue.
In cancers (like renal carcinoma), it is abnormally presented, triggering an immune response.
What role do CD8+ T cells play in tumor immunity?
They recognize tumor antigens presented by dendritic cells and kill tumor cells
How do dendritic cells present tumor antigens?
- Class I MHC → CD8+ T cells
- Class II MHC → helper T cells
What do NK cells do?
Kill cancer cells without needing antigen presentation
What activates NK cells?
- IL-2
- IL-15
- IL-12
IL-2, IL-15, IL-12
Release cytotoxic granules (like perforin and granzyme B).
Recognize:
Missing MHC
Abnormal ligand expression
Also kill antibody-tagged cancer cells via ADCC (antibody-dependent cellular cytotoxicity).
IL-2, IL-15, IL-12
Release cytotoxic granules (like perforin and granzyme B).
Recognize:
Missing MHC
Abnormal ligand expression
Also kill antibody-tagged cancer cells via ADCC (antibody-dependent cellular cytotoxicity).
What is one method by which tumors can evade the immune system?
Inhibitory molecules like PD-L1 binding PD-1
True or False: Immunosuppressive cells can block CTLs and Th1 cells.
True
What is the purpose of immunotherapy?
To target only tumor cells using the immune system
Define passive immunotherapy.
Using lab-made antibodies to target specific tumor antigens
How can monoclonal antibodies kill cancer cells?
- Complement activation
- ADCC via NK cells
- Delivering chemotherapy drugs directly
- Blocking tumor signaling pathways
What is adoptive cellular therapy?
Transferring immune cells that recognize tumors into the patient
two types:
Tumor-specific T cells (taken, activated in lab, reinfused)
CAR T cells (T cells are genetically modified with Chimeric Antigen Receptors that target tumors)
What are CAR T cells?
T cells genetically modified with Chimeric Antigen Receptors to target tumors
Describe the process of CAR T cell therapy.
Patient’s T cells are modified in a lab to recognize and kill cancer cells
Gene for CAR is designed → includes parts that recognize cancer antigens and signal the T cell to attack.
Lentivirus vector delivers this CAR gene into T cells taken from the patient.
The T cells are now called CAR-T cells.
These cells are returned to the patient → they target antigen-expressing cancer cells, leading to cell death.
What is immune checkpoint blockade?
A treatment that removes ‘brakes’ from T cells so they can attack cancer cells
What is the function of CTLA-4 in T cell activation?
It inhibits T cells in early activation in lymph nodes
CTLA-4 inhibits T cells → drugs like anti-CTLA-4 block it → T cells activate and kill tumors.
PD-1 / PD-L1: In tumors, this interaction turns T cells off.
Tumors express PD-L1 to shut down PD-1 on T cells.
Anti-PD-1 / Anti-PD-L1 antibodies block this interaction → T cells stay active → tumor cell dies.
CTLA-4 inhibits T cells → drugs like anti-CTLA-4 block it → T cells acti
What does tumor antigen vaccination involve?
A personalized vaccine to train the immune system to recognize and kill a person’s specific tumor
