Cancer immunology Flashcards
(27 cards)
what is an example of a virus that causes cancer?
epstein bar virus or HPV
what immune cells protect us from our own tumors?
T cells
what are the 2 types of tumor antigens?
1) TSA (tumor specific antigen)
2) TAA (tumor associated antigen)
what is a tumor specific antigen?
those that are unique to tumor cells and come form mutations that form a self peptide
what is a tumor associated antigen?
antigens that are not unique to tumors
what is an example of tumor associated antigen?
expression of oncofetal proteins on a tumor
what is an oncofetal antigen?
antigens found on human tumors that are normally expressed in fetus
what are two oncofetal antigens?
1) Carcinoembryonic antigen
2) alpha-fetoprotein
where do you find carcinoembryonic antigen circulating?
intestine, pancreas, liver
when do you see elevated alpha-fetoprotein?
patients with cirrhosis and hepatitis
do we have cells that attack arising tumors in our body? which?
yes, CD8+
why do some tumors not killed by our immunity arise?
they evade killing by forming variant form of itself
what mechanism induces CTL’s response to tumors?
cross-presentation
what may be low on virus induced tumor cells that have infected host cells? how does the body get around this?
B7 costimulators, we get around this using cross-presentation
how does the humoral immunity kills tumors?
1) attach antibodies and recognition of Fc receptor leading to phagocytosis
2) ADCC with natural killer cells
3) using complement and using a MAC
4) using macrophages through C3b opsonization
how does the cell-mediated immunity kill tumors?
1) T helper cells secrete cytokines and recruit macrophages to phagocytose and kill
2) activating CTL’s that recognize TSA with MHC 1
3) killing with NK cells without previous sensitization
what cancer immunotherapies can be used for tumors? how does it work?
1) Lymphokine activated killer cells
2) Tumor infiltrating lymphocytes
we take NK cells or CTL’s from dissected tumor and we activate them using IL-12
how do tumors evade immune responses?
1) they stop expressing antigens
2) they stop expressing MHC
3) they produce inhibiting cytokines
if tumor lowers MHC 1 expression, what cells will notice it and kill it?
NK cells
what do you do in the adoptive cellular therapy approach?
you isolate lymphocytes from blood or tumor and grow them with IL-2 and then put them back on the person
how effective is cancer vaccine against HPV?
100% effective
what 2 strains of HPV does the HPV vaccine target?
HPV 16/18
from what is the HPV vaccine made of?
purified virus particles of the capsid protein in HPV
how can you check for specific tumor antigen using CD8+?
you extract tumor cells and CTL’s and you stimulate them with the tumor cells until they respond, then you clone them and put them on person
