9 - The role of the immune system in cancer

Question 1

What is immune surveillance

Answer 1

Tumours have antigenic potentialities so they can provoke an effective immunological reactive with regression of the tumour

Question 2

How do cancers evade the immune response

Answer 2

Secrete inhibitory cytokines
Create a unique microenvironment
Alteration of host immune system locally and systemically
Induction of inhibitory T cell subsets

Question 3

What is cancer immunoediting

Answer 3

Recognition that immunity plays a dual role in the interactions between tumors and the host

Question 4

Three es of cancer immunoediting

Answer 4

Elimination - effective immune surveillance
Equilibrium - selection of resistant clones
Escape - Rapid proliferation of resistant clones

Question 5

Fewer macrophages

Many Tregs

Answer 5

Longer survival

Question 6

Many macrophages

Few Tregs

Answer 6

Shorter survival

Question 7

What are T regulatory cells

Answer 7

suppressor cells
o A subset of CD4 positive T-cells involved in regulating the immune response through the antigen-specific suppression of effector CD4+ and CD8+ T-cells

Question 8

What do Treg cells express

Answer 8

CD4/CD25 and FOXP3

Question 9

Problem with murine MaBs

Answer 9

patients developed human anti-mouse antibodies (HAMA) so these agents could be used only once

Question 10

How do MoAbs induce ADCC

Answer 10

Fc region on CD20-bound mAb binds to Fc on phagocytic cells
Effector cells release mediators that damage and destroy B cells
B cells are phagocytosed

Question 11

How does membrane attack complex and b cell lysis work

Answer 11

activation of remaining complement components - incorporation into the MAC
MAC forms a pore through target cell membrane
causes osmotic cell lysis

Question 12

Rituximab

Answer 12

Chimeric moAb
targets CD20 on B cells
Significant activity in non-hodgkins lymphoma

Question 13

Prophylactic cancer vaccines

Answer 13

Given to healthy individuals
Stimulate immune system to attack viruses that cause cancer
e.g cervix and liver cancer

Question 14

Immunomodulators

Answer 14

• In T cell there are ways to switch the immune system off and on
• The balance between activating receptors and inhibitory receptors is what balances our ability to mount an immune response and turn it off
• Ligands recognise these receptors e.g PDL1 to PD1 receptor
• Cancer cells over express the inhibitory receptors e.g PD1-L  CANCER CELLS SWITCH OFF THE IMMUNE RESPONSE

Question 15

What is an immune checkpoint inhibitor

Answer 15

Recognise and block the interaction of inhibitory receptors

Question 16

What is PD1

Answer 16

Inhibitory receptor on activated T-cells, B-cells, NK and myeloid cells. Inhibition of T-cell activation when engaged by ligands (PDL1/2
• PD1 expressed on T-cells when exposed to tumor, and associated with exhaustion. Blocking can restore function)