Tumour Immunology Flashcards
main difference between immune responses to viruses and cancer
Cell infected by virus presents antigens of virus which t cells recognise and attack to eliminate virus (cellular immune response)
But cancer cells come from the body’s own which have become abnormal. Although they also present antigens, they can suppress IS and make it fail to recognise them as abnormal sometimes, so that they can grow
how does role of antibodies differ in immune responses to viruses vs cancer
ab’s produced by b cells can neutralise viruses, but they are less effective against cancer cells as they are not consistently recognised as foreign by IS.
what are tumour associated antigens (TAAs)
antigens specificallly expressed/ overexpressed by cancer cells and can be recognised as foreign.
4 features of TAAs
- abnormal expression - expressed higher in cancer cells - genetic mutations
- diversity - vary among different cancer types
- location - can be found on/in cancer cells or secreted into extracellular environment
- types - diff types like tumour-specific antigens , tumour-associated differentiation antigens and cancer-testis antigens
- immunogenicity - some can stimulate a strong immune response while some may not/ may suppress IR
- diagnostic and therapeutic potential - can be targets for cancer immunotherapy
3 ways a successful immune response against cancer can occur
- t cell activation that recognises TAAs on surface of cancer cells
- ab production that targets TAAs
- recruitment of other immune cells like NK cells and macrophages, to attack cancer cells
3 ways tumours can resist immune responses
- downregulating TAAs - makes it harder for immune cells to recognise and attack tumours
- producing immunosuppressive molecules e.g. cytokines that inhibit t cell activation/ immune checkpoint molecules that prevent T cells attacking cancer cells
- modulating tumour microenvironment - make environment less hospitable to immune cells/ attract less effective immune cells
- developing resistance to therapy like immunotherapies (making it harder for IS to eliminate tumours)
what is active tolerization
Type of immunotherapy that aims to induce immune tolerance to patients’ own cancer cells so they may fail to mount an effective response against the tumour allowing it to grow and spread - prevents IS attacking normal cells and tissues as can distinguish between cancer cells and healthy cells
why are immunodeficient mice useful in research
to study IS function and develop and test treatments for immune-related diseases in a more natural environment.
what are immune-privledged sites
sites in body where IS is not allowed to function normally/immune responses are regulated to prevent damage - less subject to IR
e.gs of immune-privledged sites
eyes, brain, testes, placenta
how does the cytokine ifn-gamma play an important role in IR against viral and bacterial infections and regulate tumour growth
enhances phagocytic activity of macrophages
enhances the cytotoxic activity of NK cells
Induces expression of MHC molecules on target cells which facilitates recognition and destruction of infected/abnormal cells
can promote differentiation and activation of TH1 cells
What are MHC molecules and why do they play important role in adaptive immune response
proteins present on surface of nearly all cells
present foreign antigens to T cells
where are MHC class II primarily found
on APCs like dendritic cells, macrophages and b cells
2 ways tumour cells can evade destruction by cytotoxic T cells
Losing MHC-I molecules on their surface - prevents CTL recognition
produce immunosuppressive molecules like cytokines (TGF-b/IL-10) - inhibit CTL activity
genetic mutations to make less recognisable
secrete factors to recruit immunosuppressive cells (Tregs)
