16 - Tumor Immunology

Question 1

How can the immune system distinguish between cells that are normal or foreign/mutated?

Answer 1

will be displayed on MHC molecules of cells

Question 2

What does syngeneic mean?

Answer 2

genetically identical

Question 3

How can your immune system reject a tumor?

Answer 3

if the armies of T and B cells specific to the tumor antigen are ready once the tumor pops up

Question 4

What are the 3 intrinsic proteins will the immune system see as foreign?

Answer 4

viral | mutated | embryonic

Question 5

What are the 4 principle effector cells?

Answer 5

CTLs | NK cells | complement | mcarophages/monocytes

Question 6

What cell induces indirect T-cell activation?

Answer 6

APCs and Th cells

Question 7

What cell induces direct T-cell activation?

Answer 7

CTLs

Question 8

What happens to the tumor cell if it down-regulates the expression of their MHC?

Answer 8

NK cell will not see it and will kill the tumor cell because it thinks there is something wrong with the cell

Question 9

What is the killer inhibitory receptor?

Answer 9

on the NK cell and recognizes MHC | if activated by MHC = inhibits NK cell from inducing apoptosis

Question 10

What are plasma cells?

Answer 10

activated B-cells that secrete antibodies specific to the antigen

Question 11

How can antibodies induce cell killing?

Answer 11

NK cells Fc receptors attach to Fc region on antibody that is attached to the antigen = brings NK cell close to target

Question 12

How do macrophages find tumor cells?

Answer 12

aggregation of immune complexes on tumor surface = allows cross-linking of Fc receptors on macrophage = activates the macrophage

Question 13

What does the macrophage do to the tumor cell?

Answer 13

phagocytosis and nitric oxide (NO) release = damage DNA

Question 14

What is the macrophage—NK tandem?

Answer 14

macrophage releases nitric oxide (NO) into target cell = NO induces stress-induced ligands which NK-cells detect

Question 15

What are the first 2 steps of complement activation?

Answer 15

antibodies latch onto target cells | complement proteins latch onto these antibodies &raquo_space;> cascade effect

Question 16

What is the end result of complement activation?

Answer 16

MAC complex = pore on target cell

Question 17

What are the 8 ways tumor cells escape the immune system?

Answer 17

low tumor immunogenicity | capping | immune suppression | mask antigens | down-regulating death receptor genes | induce IAPs | activate death receptors on immune cells | modify apoptotic proteins

Question 18

What does “low tumor immunogenicity” mean?

Answer 18

no expression of tumor-specific antigen, adhesion molecules, co-stimulatory molecules

Question 19

What is the “capping” mechanism that tumors do to hide from the immune system?

Answer 19

phagocytose and internalize antibodies that latch on it

Question 20

What is the “antigen masking” mechanism that tumors do to hide from the immune system?

Answer 20

glycosylate their surface proteins so antibodies can’t bind to it

Question 21

What gives rise to resistant tumor cells?

Answer 21

not all tumor cells were gone from previous treatment = survivor tumor cells that are resistant to the drugs of the previous treatment

Question 22

What is immunotherapy?

Answer 22

boost immune system | create antibodies specific to tumor-cell markers and inject into patient

Question 23

How can you counteract the capping mechanism tumors use?

Answer 23

conjugate a drug/toxin to the antibody specific to tumor cell = tumor cell internalize antibodies and the drug/toxin too = kills tumor cell

Question 24

How can you radiate tumor cells directly?

Answer 24

conjugate a weak radioisotope to the antibody specific to tumor cell = tumor cell internalize antibodies and radioisotope = cell is irradiated overtime

Question 25

Why is gene therapy faulty?

Answer 25

cannot deliver the vector into every tumor cell because there are millions of them