cancer and immunity Flashcards
what things may happen after cell mutation
if a cell is mutated to a transformed cell which may potentially become a cancer one of 3 things may happen; elimination, equilibrium or escape
elimination: surveillance by immune system recognises transformed cell and is destroyed.
an equilibrium is acheived when cells are dividing rapidly as a cancer however the immune system is attacking and so causing it to maintain size, symptoms are not present here since size is managed (tumour dormancy)
if the cell escapes the immune system the cancer grows and becomes malignant
what is immunological surveillance
immunological surveillance; the immune system eliminates/inactivates cancer cells
immunogenic tumour arise in immunodeficient mice, progressive tumour variants arise in normal/immunocompetant mice
how can vaccines be used to protect against cancer
prophylactic cancer vaccines are successful (before cancer happens); cervical cancer HPV vaccines, liver cancer: herpes B vaccine
therapeutic vaccines (after cancer) less effective; dendreon’s provenge; a prostate cancer vaccine produced with patients own cells
how is comstimulator T cell binding affected in cancer
when T cells are stimulated by APCs presenting antigen with MHC costimulatory molecules used, 2 inhibitory ones which have strong links with cancer are PD1 on T cell binding to PDL1 on APC, and CTLA4 on T cell binding to CD80 or CD86, receptors on T cell, ligands on APC
knockouts of these 2 costimulators show reduced cancer
cancer cells express PD-L1 to prevent T cell stimulation when antigen is presented as well as CTLA4 pathway, however risk of autoimmunity
what are tumour infiltrating lymphocytes
therapy with tumour infiltrating lymphocytes: tries to improve specificity of knockouts as they do not simply target cancer activated T cells,
tumour infiltrating lymphocytes: T cells are isolated from surgically removed tumours, they are then grown with IL-2, they are then selected and expanded and infused as tumour infiltrating lymphocytes to the patient
advantage of TIL therapy; multiple specificities against neo-antigens and tumour associated antigens
disadvantage of TIL therapy; difficulty to reliably grow TILs from cancer patients (melanomas are most successful), unknown fine specificity of TILs
how are engineered T cells used in cancer therapy
engineered T cells; genes for TCR or chimeric antigen receptors are transferred using viral vector into primary human T cells, these cells then selectively target specific cancer antigens, to improve cancer therapy both TCRs and CARs, advantage of TCRs is that they recognise proteins via HLA, problem with CARs is they can only recognise cell surface proteins, only 20% of cell proteins are cell surface proteins
what are tumour specific antigens
tumour specific antigens are antigens only found in cancer cells and not in other somatic cells, cancer associated antigen is found at high levels in cancer cells but at lower levels in other tissues, however benefit of associated is they are very common in cancers, most successful example is CD19 antigen
