Lecture 10 Tumour immunity Flashcards
What is a tumour and what are benign and malignant tumors (metastasize and anaplasia)
Cells that have lost control of cell cycle will produce a clone of cells - tumour
Benign - unable to invade healthy surrounding tissue incapable of indefinite growth (easily removed by surgery eg wart)
Malignant - Becomes progressively more invasive, may metastasize (get seperated and invade other tissues) and become anaplasia (advanced stage of malignant tumour where cells lack differentiation
3 types of common Cancers
Cancers are classified according to their embryonic tissue origin
Carcinomas - malignant tumors that develop from epithelial cells
Sarcomas derive from mesodermal connective tissue (bone, fat)
Lymphomas, myelomas and leukemias derive from hematopoietic stem cells
What are the 4 types of malignant transformation of cells
Chemical substances
Physical agents
Radiation
Viruses
What are the 5 common properties of tumours
Failure to respond to regulatory signals that control normal growth and repair
Invasive growth
Metastatic growth at distant sites
Monoclonal origin with genetic and phenotype changes during development
Altered membrane antigens
What are the 5 major types of tumour antigens
Differentiation antigens (associated with specific stages of cell development) Mutated forms - of normal antigens Normal antigen - in excessive amounts Cancer antigens Viral antigens
How do we have immunity to tumors
NK cells, Tc cells and macrophage and/or antibodies will attack cancer cells however abnormal antigens not presented properly to Tc cells
Which are the most important protection to tumors
NK cells, immediately activated by interferons and IL -12 from virus infected cells, activated NK cells enter tissues and kill tumours. Innate immunity
Describe the target cell recognition by NK cells
Based on activating and inhibitory signals:
Healthy cells produce inhibitory signal (MHC 1 produces signal)
Infected, damaged or cancer cell there will be activating signal (Cancer cells have less MHC1 molecules)
What are the 3 receptors on NK cells which are important for cytotoxic activity
Receptor for MHC 1 molecules
Receptor for recognising proteins on stressed cells (NKG2D receptors)
Receptor for antibody on target cells (CD16)
What are the 6 NK cell functions
Destruction of tumour cells ADCC against tumour cells GVH disease Destruction of virus infected cells Destruction of bacteria and fungi Control of hematopoiesis
What are the 5 other cells important for protection against tumours
Natural killer T cells Natural killer dendritic cells Regular T cells Macrophages Antibodies to tumour antigens
What are the 5 ways in which tumour cells avoid immune responses
Mutation - initially monoclonal but mutations occur after
Immunosuppression - tumours of B cells suppress antibody formation and T cell supress CMI
Regulatory cells - usually CD8 T cells
Blocking factors - Inhibit cell mediated cytotoxicity and ADCC
Genetic factors
What are the ways in which tumour cells can be controlled
Active immunotherapy - activates macrophages and releases cytokines Passive immunotherapy Anti-tumour vaccines Drug therapies - chemo, hormonal, targeted and immuno Monoclonal antibodies - can be targeted to tumour cells
