Chapter 12 Flashcards
What cells are immune cells derived from?
Hematopoietic stem cells in the bone marrow
What is humoral immunity?
The aspect of immunity being mediated by antibodies.
What is the Fab region on an antibody?
They are highly variable regions on an antibody which are responsible for antigen specificity.
What is the Fc region on an antibody?
A region that functions in regulating the immune response.
What do B-cells do?
B-cells produce antibodies and can become B-memory cells.
Which two types of T-cells mediate immunity?
- T-helper cells (CD4)
2. Effector T-cell (CD8)
What is the relation between T-cells and antibodies?
T-cells have receptors on their membranes that bind and recognize antibodies.
What are cytokines?
Cytokines are small secreted proteins which are the major signaling proteins for B and T-cells
In which three ways does the immune system work in an immunosuppressive way?
- Protects against viruses and bacteria
- Helps resolve inflammation
- Kills tumor cells
What are the seven steps of the cancer immunity cycle?
- Release of cancer cell antigen after tumor cell death
- Presentation of cancer antigens to APC
- Activation of T-cells in lymph nodes
- Transport to the tumor
- T-cells infiltrate the tumor
- T-cells recognize cancer cells
- Tumor cell is killed
In which two ways does a T-cell recognize cancer cells?
- Tumor-specific antigens that are unique to the tumor
2. Antigens that are differentially expressed on the tumor compared to healthy cells.
How does a T-cell kill a tumor cell?
By either injecting granzymes and perforins into their cytoplasm and express ligands for Death Receptors on the cancer cell.
What role does MHC play in immune response?
Antigens are being presented to T-cells by APC on their MHC molecules.
Can T-cells detect free antigen?
No, T-cells can only detect antigen presented to them by MHC from antigen-presenting cells.
Describe the activation of T-cells.
T-cells use their TCR to recognize antigen presented by APC on the MHC molecules. T-cells need a co-stimulatory signal that is mediated by the CD28 receptors on the T-cells that bind to B7 ligands on the APC.
How are some types of lymphomas invisible to the immune system?
The cells do not present B7 cells and T-cells cannot recognize it without the co-stimulatory signal.
What molecule inhibits T-cell activation by APC?
CTLA-4 on T-cells binds more strongly to B7 than CD28, thereby preventing the activation of T-cells by APC.
What enzymes are involved in the signal transduction of an activated T-cell?
Kinases (PI3K, Protein Kinase C) and Phosphatases (SHP phosphatase)
How do cancer cells inhibit the T-cell response?
Cancer cells express PD-L1 on their surface which binds to PD-1 on T-cells. It then recruits a phosphatase which has an inhibitory effect on the T-cell response.
What are the three E’s of immunoediting?
- Elimination of cancer - cancer cells are killed
- Equilibrium - the portion of cancer cells that survive an immune response become more “fit” to survive
- Escape - cells have adapted to evade the immune system
