W07_04 Tumor Host Interactions Flashcards
what are 5 effects of tumor on host?
immunosuppression; cancer cachexia; local effects (e.g. mass effect); paraneoplastic syndromes; functionality of tumors
why do some normal proteins become antigens when they’re overexpressed?
overexpression causes more exposure. sometimes, normal levels are so low that it can’t induce tolerance
how do NK cells activate against neoplastic cells?
may be activated by tumours that don't express MHC class I; recognize stress-induced antigens on the cell surface
do antibodies offer prophylaxis against spontaneous tumours?
no evidence shows this yet; monoclonal Abs can be used for treatments
name 6 mechanisms tumors develop to avoid immune system
clonal selection for antigen-negative variants;
underexpress MHC I (although NK cells can come to attack these ones);
lack of co-stimulation to induce anergy;
immunosuppression (e.g. TGF-beta);
apoptosis of CTLs;
antigen masking
hemangioma, leimyoma, meningioma are examples of benign tumours that cause local effects
ok
adrenal cortical adenoma can cause which syndrome?
cushing’s syndrome
b-cell adenoma of pancreas can cause which syndrome?
hypoglycemia
parathyroid adenoma can cause which syndrome?
hypercalcemia
ovarian thecoma can cause which syndrome?
hyperestrogenism
define paraneoplastic syndrome
a symptom complex in a patient that can’t be described by the local or distant spread of the tumour (e.g. ectopic ACTH in SCLC)
squamous cell carcinoma of the lung can cause which syndrome?
hypercalcemia
what’s the mechanism behind cancer cachexia?
cytokines - e.g. TNF (+IL-1, IFN-y), factors that promote muscle catabolism
what are the complications of cancer cachexia?
impedes chemotherapy;
significant cause of cancer death
give an example of how a tumor might suppress the immune system
TGF-beta
