Immunobiology of Tumors Flashcards
What are the tumor antigens?
Differentiation antigens
Mutated proteins
Viral coded proteins
Excessive amounts of normal proteins
Cancer antigens
What are the categories of malignancies?
oncogenic virus and chemical carcinogen
Does oncogenic virus malignant transformation result in identical or dissimilar new antigens? What about chemical carcinogens?
oncogenic- identical
chemical- dissimilar
What virus has been used in laboratories to induce tumors?
SV40 (oncogenic)
What types of immunotherapy are offered for tumors?
antibody: antibodies tailored to attack tumor cells
CTLs: antibody compounds that target tumor cells
inhibit Tregs: tumor cells use Tregs to suppress host immune system
How do tumors escape immune defenses?
Failure to produce tumor antigen therefore not recognized by T-cell.
Mutations in MHC genes or genes needed for antigen processing therefore not recognized by T cell.
Production of immuno-suppressive proteins, resulting in inhibition of T cell activation.
What molecules inhibit T cell activation?
PD-L1 and TGFb
What tumor antigens are produced by T-cells and what happens if they loose expression?
MHC-1 and TAP
evasion of immune system by tumor
What cytokines are immunosuppressive?
IL-10 and TGFb
What does tolerogenic mean and how does it relate to evasion of the immune system by tumors?
Tumor cells present antigens in a tolerogenic form, this form does not favor T-cell activation.
Co-stimulation does not occur.
What is antigen masking?
A way tumors avoid the immune system, blocking antibody recognition of tumors
What cells are involved in tumor destruction?
T cells
macropahges
NK cells
What are 5 protective anti-tumor immune strategies?
Stimulation of NK cells, macrophages, and depressed regulatory cells. Cytokine activated cytotoxic cells. Immunotoxins.
Which anti-tumor strategy is the most successful?
Not any one mechanism on its own.
What is the protein used in canine melanoma vaccine and why would you think it should not be effective? How do we get around that?
Tyrosinase protein, it is a self protein so it should not mount an immune response
Use human tyrosinase antigen instead of canine!
