tumor immunity Flashcards
do tumors express MHC II?
no most do not.
how are tumor cell antigens presented to T cell?
usually a dendritic cell or other antigen presenting cell will phagocytose a tumor cell and digest the tumor antigens to present them to the tcell
how do tumors escape immunity?
through microcosm of evolution. highly antigenic tumor cells are removed by the immune system, leaving behind cells that more resistant and over time a tumor that mis composed of cells that are not that antigenic will be formed. this is the escape phase (or when a cell can escape immunity).
what is another way a tumor can escape immunity
through recruiting regulatory cells to protect it and thus spread unchallenged.
do tumors show low or high levels of MHC I?
low levels.
what cells kill tumors without MHC I?
natural killer cells
what cells kill tumors with MHC I?
Cytotoxic t lymphocytes.
what is another mechanism tumors can evade T cells?
they can express TRA but no costimulatory molecule and thus leave the t cell anergic.
what is the classification of t regs?
CD4+, CD25+, FoxP3 +
how do regulatory T cells down regulate auto reactive T cells?
they must interact on the same antigen presenting cell. it releases TGF-b and IL-10.
what effect does TGF-beta have on T reg cells?
it activates them
what is BCG and how is it used?
bacillus calmette Guerin is attenuated strain of mycobacterium bovis. it invades tumor cells. it acts as an adjuvant for immunity
what does CTLA-4 do?
it acts to hinder the immune response. it binds to B7 with more avidity than does CD28 and delivers inhibitory signals to activated T cells. (antibodies to CTLA-4 block that inhibition).
what does trastuzumab treat, what does it inhibit?
breast cancer. ERBB2 signaling (HER2)
what does bevacizumab treat, what does it inhibit?
colon cancer, VEGF signaling
