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| Question | Answer |
| Examples of tumor-specific antigens include the abnormal products | of ras and p53 genes. |
| Oncofetal antigens are another important class of tumor antigens. Examples are | alphafetoprotein (AFP) and carcinoembryonic antigen (CEA). normally produced in embryonic development and disappear by the time the immune system is fully developed. Thus self-tolerance does not develop against these antigens. |
| Abnormal proteins are also produced by cells infected with oncoviruses... | EBV and HPV. Cells infected by these viruses contain latent viral DNA which is transcribed and the resulting protein produces an immune response. |
| ras oncogene induces synthesis of | cyclin D1 |
| The HER family | epidermal growth factor family of receptors compromises 4 transmembrane proteins with distinct properties- all regulate cell proliferation |
| tumours mostly express | TAA = tumour associated antigens- these can be used for diagnostics |
| MUC-1 | breast and other carcinomas |
| CALLA | subset of immature B cells |
| hCG | wide range of CA |
| PSA | prostate |
| MAGE-1, MART-1 | melanoma |
| tumours mostly express | TAA = tumour associated antigens- these can be used for diagnostics |
| tumours use various strategies to | weaken the immune response |
| tumour escape strategies | 1.produce immunosupressive cytokines, 2. inhibit DC maturation=T cell anergisation, 3. promote Treg cell mediated inhibition of anti tumour responses, 4. downregulate TCR associated signalling molecules in infiltrating peripheral T cells, 5. develop a disorganised vasculature that lacks the approprite integrin expression for lymphocyte infiltration, 6. lose or alter expression of TAA or TSAs 7. downregulate classical MHC class 1 to block CTL activation, 8. Ag masking, 9. antigenic modulation, 10. tolerance of host to tumour antigens |
| what is used for immunotherapy of cancer? (7) | 1.CTCs, 2. NK cells 3. macrophages 4. dendritic cells 5. monoclonal abs 6. bispecific abs 7. gene tx |
| two types of tumour associated antigens | 1. virally induced, 2. chemically induced |
| virally induced tumour antigens | oncogenic DNA and RNA viruses encode for these - shared by all tumours induced by same virus and induce strong immune response |
| chemically induced tumour antigens | random mutagenesis causes unique expression of antigens - induce strong immune responses |
| HTLV-1 causes | adult t cell leukaemia |
| EBV causes | Burkitts lymphoma and lymphoma in immunosupression |
| HPV causes | cervical cancer |
| Hep B and C causes | liver cancer |
| H pylori causes | stomach cancer |
| role of EBV in lymphoma | chromosomal translocation creates a B cell tumour |
| mechanisms of inactivating p53 | 1.mutation in DNA binding domain, 2. deletion of carboxy terminal domain, 3. multiplication of MDM2 gene, 4. viral infection, 5. deletion of p14 gene, 6. mislocalisation of p53 to cytoplasm |
| TSA | tumour specific antigens |
| 2 categories of tumour antigens (TAA and TSA) | 1.Products of Mutated Oncogenes and Tumor Suppressor Genes, 2. Products of Other Mutated Genes |
| Products of Other Mutated Genes | 1.Overexpressed or Aberrantly Expressed Cellular Proteins 2. Tumor Antigens Produced by Oncogenic Viruses, 3. Oncofetal Antigens, 4.Altered Cell Surface Glycolipids Glycoproteins, 5.Cell Type-Specific Differentiation Antigens |
| Any protein produced in a tumor cell that has an abnormal structure due to mutation can... | act as a tumor antigen |
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