Tumour immunology

Question 1

What are the potential immune mechanisms against tumours?

Answer 1

Antibody and complement
ADCC
Direct NK cell cytotoxicity
Cytotoxic T cells recognissing tumour-derived peptides presented by MHC-I

Question 2

What is the hypothesis of immune surveillance?

Answer 2

Lymphocytes can prevent the development of tumours. The evidence for surveillance is increased frequency of certain tumours in immunosuppressed individuals; Kaposki’s sarcoma in and NHL in HIV patients)

Question 3

EBV is associated with which cancers?

Answer 3

Lymphomas (burkitts in malaria) and nasopharyngeal carcinoma

Question 4

HPV is associated with which cancer?

Answer 4

cervical cancer

Question 5

Hepatitis B and C is associated in which cancers?

Answer 5

Liver cancer

Question 6

HTLV-1 is associated with which cancer?

Answer 6

adult T cell leukaemia.

Question 7

Stomach cancer is associated with which bacterium?

Answer 7

Helicobacter pylori

Question 8

Poorly functioning immune systems increases the incidence of which cancers?

Answer 8

Primary immunodeficiencies increase the incidence of lymphomas in secondary lymphoid tissues with a close association with EBV, leukaemias in primary lymphoid tissues.

Question 9

Can immunosuppression increase incidence of cancer?

Answer 9

Yes, (cyclosporine) for organ transplants or AIDS also increased incidence of tumours associated with infectious agents such as hepatitis B, C and HPV.

Question 10

Can virus induced tumours be associated with chromosomal translocations?

Answer 10

Yes, the translocation of the c-muc gene to the immunoglobulin heavy chain gene locus which occurs in Burkitt’s lymphoma resulting in malignant B cells.

Question 11

Why is the IS inadequate to control most tumour growth?

Answer 11

Due to self-tolerance; the IS should not respond to a tumour unless some component of the tumour cell is altered and appears foreign. This might occur because of an alteration to a host protein caused by a mutation or a change in post-translation modification. MHC-I restricted CD8-CTL against human melanoma antigens have been isolated and target antigens for some of these cloned sequenced.

Question 12

What are the differences between tumour and normal cells detected by antibodies?

Answer 12

Whilst tumour specific antigens are rather uncommon a number of tumour associated antigens, showing greater expression on tumour than normal tissue exist such as prostate-specific antigen (PAA) and Her-2. These provide target for antibody-mediated cytotoxic therapy. Targeting therapy to tumour vasculature also shows some promise (anti-angiogenesis)

Question 13

What are tumour cell’s interaction with the immune system?

Answer 13

Tumour cells also evade the immune response through:
Down-regulation of surface molecules
Inhibitory receptors/ligands, inhibitory soluble factors, immune cells in the tumour microenvironment are functionally impaired.
Cytokines, soluble factors or microvesicles modulate systemic immune responses.

Question 14

Can tumours express IL-10

Answer 14

Yes, which actively inhibits DC maturation, inhibits CD80 and CD86 expression (or TGF beta); lack of costimulation, immunological tolerance of tumour arises.

Question 15

What is immunoediting?

Answer 15

A response or tolerance mechanism of recognition of surface molecules, new variant, Darwinian selection of that tumuor.

Question 16

Describe immunotherapies

Answer 16

Antibody that recognises tumour; ADCC/ antibody-toxin conjugate.
Cell transfer of sensitised T cells (cytotoxic) which are insufficient in patietn
Vaccines; tumour antigen

Question 17

What are the two types of tumour vaccines?

Answer 17

Prophylactic; virus associated tumours (HBV and HPV)
Therapeutic: tumour antigens; most causes aim is primarily to induce specific cytotoxic T cell responses but sometimes antibody is also desirable.