16 - Tumor Immunology Flashcards
How can the immune system distinguish between cells that are normal or foreign/mutated?
will be displayed on MHC molecules of cells
What does syngeneic mean?
genetically identical
How can your immune system reject a tumor?
if the armies of T and B cells specific to the tumor antigen are ready once the tumor pops up
What are the 3 intrinsic proteins will the immune system see as foreign?
viral | mutated | embryonic
What are the 4 principle effector cells?
CTLs | NK cells | complement | mcarophages/monocytes
What cell induces indirect T-cell activation?
APCs and Th cells
What cell induces direct T-cell activation?
CTLs
What happens to the tumor cell if it down-regulates the expression of their MHC?
NK cell will not see it and will kill the tumor cell because it thinks there is something wrong with the cell
What is the killer inhibitory receptor?
on the NK cell and recognizes MHC | if activated by MHC = inhibits NK cell from inducing apoptosis
What are plasma cells?
activated B-cells that secrete antibodies specific to the antigen
How can antibodies induce cell killing?
NK cells Fc receptors attach to Fc region on antibody that is attached to the antigen = brings NK cell close to target
How do macrophages find tumor cells?
aggregation of immune complexes on tumor surface = allows cross-linking of Fc receptors on macrophage = activates the macrophage
What does the macrophage do to the tumor cell?
phagocytosis and nitric oxide (NO) release = damage DNA
What is the macrophage—NK tandem?
macrophage releases nitric oxide (NO) into target cell = NO induces stress-induced ligands which NK-cells detect
What are the first 2 steps of complement activation?
antibodies latch onto target cells | complement proteins latch onto these antibodies »_space;> cascade effect
What is the end result of complement activation?
MAC complex = pore on target cell
What are the 8 ways tumor cells escape the immune system?
low tumor immunogenicity | capping | immune suppression | mask antigens | down-regulating death receptor genes | induce IAPs | activate death receptors on immune cells | modify apoptotic proteins
What does “low tumor immunogenicity” mean?
no expression of tumor-specific antigen, adhesion molecules, co-stimulatory molecules
What is the “capping” mechanism that tumors do to hide from the immune system?
phagocytose and internalize antibodies that latch on it
What is the “antigen masking” mechanism that tumors do to hide from the immune system?
glycosylate their surface proteins so antibodies can’t bind to it
What gives rise to resistant tumor cells?
not all tumor cells were gone from previous treatment = survivor tumor cells that are resistant to the drugs of the previous treatment
What is immunotherapy?
boost immune system | create antibodies specific to tumor-cell markers and inject into patient
How can you counteract the capping mechanism tumors use?
conjugate a drug/toxin to the antibody specific to tumor cell = tumor cell internalize antibodies and the drug/toxin too = kills tumor cell
How can you radiate tumor cells directly?
conjugate a weak radioisotope to the antibody specific to tumor cell = tumor cell internalize antibodies and radioisotope = cell is irradiated overtime
Why is gene therapy faulty?
cannot deliver the vector into every tumor cell because there are millions of them
