Tumor Immunology Flashcards
What is immunoediting?
the role of the immune system in neoplastic development as a series of stages (Elimination, equilibrium, escape)
What are tumor associated Antigens (TAA)?
Antigens that are not readily found on the corresponding normal cell. Often they are found on normal cells, but in much lower quantities; usually overexpressed or abnormally expressed by the tumor
What are viral gene products?
tumors known to be caused by tumor viruses; 20% of tumors are caused directly or indirectly by viruses
- HTLV-1 and -2: Sézary syndrome/mycosis fungoides
- HPV: cervical cancer
- hepatitis virus: liver cancer in developing world
- Epstein Barr Virus: Burkitt lymphoma and nasopharyngeal carcinoma
What are mutated gene products?
mutated proteins as a result of Chemical and physical carcinogens leading to Tumor Specific Antigens (TSA).
what are normal gene products?
Antigens that are normally expressed by cells, but may be overly expressed/lineage specific (PSA, HER-2), expressed when they shouldn’t (carcinoembryonic antigen), or clonal antigens.
T or F: carcinoembryonic antigens are found in normal adults
False, found in the blood of patients with colon carcinoma and other cancers.
What are the indication for using the CEA kit in colonic cancer?
- a high index of suspicion of colon cancer
- when such a cancer has been removed, to confirm complete excision
- Too many false positives.
How do CTLs target tumors?
CTL can kill tumor cells by inducing apoptosis via either perforin or Fas-mediated pathways. also secrete IFNgamma upon engagement of their TCR, attracting macrophages.
patient-derived T cells that recognize TAAs are often ineffective, why?
tumors upregulate PD-1 ligands which binds PD-1 receptors on CTL and suppress them, so they escape lysis.
NK cells are also known as?
Large Granular lymphocytes (LGL)
How do NK kill tumors?
recognize “stress-related” markers on tumor cells, using a small number of NK receptors which are neither immunoglobulin nor TCR.
T or F: NK cell receptors are down-regulated if the target cell expresses Class I MHC
True
T or F: Tumor cells escape NK cells if they down regulate their MHC I receptors.
False. if the tumor decreases Class I, thinking to evade CTL, then it becomes a NK target
What are tumor-infiltrating lymphocytes (TIL) used for?
Adoptive cell transfer therapy. The T cells are greatly expanded and transfused back into patients after partially destroying the patient’s immune system.
What are blocking factors?
Factors secreted into plasma by tumor cells to escape the immune system. Blocking factors include shed tumor antigen (or antigen-MHC complexes) and sometimes antibody against tumor antigens, which don’t harm the tumor while shielding it from T cells.
