Immunology, neoplasia and tumours Flashcards
For what reasons is there a link between neoplasia and the immune response?
- Increased tumour susceptibility in immunosuppressed humans
- Presence of leukocytes infiltrates around tumours
How can malignant tumours evade the immune system?
Malignant transformation is associated with complex genetic alterations leading to the expression of proteins that are seen as non-self by the immune system
What are tumour associated antigens?
Proteins, glycoproteins, glycolipids or carbohydrates expressed on the tumour cell surface
Compare tumour specific antigens and tumour associated antigens
- Restricted to tumour cells, antigens encoded by mutated genes, antigens from oncogenic viruses
- Both tumour and normal cells, over expressed antigens
How are tumour antigens used for diagnostic purposes?
Allow non-invasive detection and monitoring when released into the blood stream. They can be use to localize tumours and to detect metastases
Which cells are involved in tumour immunity in the innate response?
NK cells
Macrophages
Which cells are involved in tumour immunity in the cell mediated response?
CD8 T-lymphocytes
CD4
How is the anti-body mediated part of the adaptive immune response involved in tumour immunity?
- Activation of complement and MAC
- Antibody dependant cell mediated cytotoxicity by NK cells
What are the 4 ways a tumour cell can evade the immune response?
- Reduced expression of MHC molecules
- Antigen masking
- Immunosuppression
- Tolerance
What are the consequences of reduced expression of MCH for a tumour cell?
Escape from CD8 and CD4 attack but triggers NK cells
What are some direct effects of tumours?
Obstruction Pressure Replacement of normal tissue Bone fracture Malabsorption Haemorrhage Infection
Where in the body can tumour obstruction occur?
Tubular organs - GI tract, respiratory
Artery, vein, lymph
Pedunculated - e.g. intestine strangulation
How do tumours cause pressure damage?
Tumours exert a pressure on surrounding tissue and atrophy when situated in a non-expandable space e.g. cranial cavity
Benign tumours often replace surrounding tissue by causing … ?
Pressure atrophy
How can tumours cause malabsorption
Infiltrate neoplasms of the gut wall - e.g. cause a diffuse thickening which reduces the absorptive functions of the intestine
