Tumor Immunology Flashcards
tumor immunology
study of the antigens of tumor cells and the immune response against those antigens
immune surveillance
- anti-neoplastic function of the immune system
- constantly monitoring
- part of normal function
- increasing DNA mutations alter expressed proteins
- eventually viewed as non-self by the immune system
- may be subject to attack
tumor cell markers
characteristic substances produced by cancer cells:
- hormones: catecholamines
- enzymes
- genes
- antigens
- antibodies
tumor cell markers are used to: _____
- screen and identify individuals at high risk for cancer
- diagnose specific types of tumors
- observe clinical course of cancer (can monitor concentrations over time)
Tumor Specific Antigens (TSA)
- antigens that are only associated with tumor cells
- if present, cancer is indicated
- point mutations: changes produce catalogued abnormal proteins
- viral antigens
- cancer-germline gene products: proteins associated with sperm development
Tumor Associated Antigens
- not specific to a particular tumor
- if they’re present, doesn’t necessarily indicate cancer
- normal proteins with increased expression
- proteins with altered structure: changes produce uncatalogued proteins
- oncofetal antigens: antigens normally only produced during fetal development and then silenced after birth
- differentiation antigens: antigens associated with specific tissue types
Human Chorionic Gonadotropin (HCG)
- produced in high levels during pregnancy, but not produced when not pregnant
- associated with ovarian and testicular cancer
Alpha Fetoprotein (AFP)
- liver cancer
- oncofetal antigen
Carcinoembryonic Antigen (CEA)
- colon cancer, breast cancer
- oncofetal antigen
Prostate Specific Antigen (PSA)
-increased expression in prostate cancer
primary immunologic response to tumors
T-cell-mediated cytotoxicity
immunologic responses to tumors
- T-cell-mediated cytotoxicity
- NK cell-mediated cytotoxicity
- macrophage-mediated cytotoxicity
- complement-mediated cytotoxicity
- antibody dependent cell-mediated cytotoxicity (ADCC)
immune evasion
when the cancer cell has changed so much that cytotoxic T cells can no longer recognize it
immune evasion mechanisms
- antigenic changes (low immunogenicity, antigen masking, antigen modulation, antigen release)
- immunosuppression
- speed of growth
low immunogenicity
- down regulation of MHC I molecules
- pull in surface molecules that are targets for immune attack
antigen masking
-cell secretes coat that covers surface that blocks other cells from physically interacting with it
antigen modulation
-if an antigen is recognized, the cell will downregulate that particular antigen and upregulate another antigen
antigen release
can throw off antigens and increasing concentration of antigens can block immune cells from finding actual cell that it needs to attack
immunosuppression
the cell releasing cytokines that induce suppression of T-cells
