2G - Neoplasia

Question 1

Cancer

Answer 1

is a disease characterized by abnormal, uncontrolled growth of cells
◦ (Neo-plastic- new growth)

Question 2

cancer cell characteristics

Answer 2

◦ Immortal 
◦ Invade other tissues 
◦ Metastasize @ distant sites via
	‣ Blood 
	‣ Lymph

Question 3

noninfectious causes of cancer

Answer 3

◦ Chemical induced mutations
◦ UV Radiation
◦ Congenital
◦ Spontaneous

Question 4

infectious causes of cancer

Answer 4

◦ Feline leucosis virus (FeLv)
◦ Enzootic bovine leucosis virus (EBL)
◦ Human Papilloma virus (HPV)

Question 5

tumor specific antigens

Answer 5

◦ Tumor cells express tumor specific molecules, (antigens) on their surface → helps with tumor diagnosis, (e.g. PSA for prostate cancer) and treatment
◦ Tumor specific antigens- only found on tumor cells maybe from oncogenic viruses or altered cellular products encoded by mutated genes.
◦ The immune system attacks neoplastic cells that express tumor specific antigens → suppresses tumor development
‣ Higher risk of cancer in immunosuppressed patients (eg HIV)

Question 6

immune response against neoplasia

Answer 6

◦ Innate immune response is the first line of defense
‣ NK cells- kill neoplastic and virally infected cells
‣ Interferon is released by NK cells and T lymphocytes
• Stimulates macrophages to release chemicals and enzymes to kill neoplastic cells

Question 7

adaptive immunity against neoplasia

Answer 7

◦ Cytotoxic T cells (CTL) most important
‣ Recognize foreign antigen from neoplastic cells
‣ Release lytic granules to kill the cell and other enzymes that initiate apoptosis of the cell
◦ Th cells promote the action of CTL’s
◦ B Lymphocytes also produce antibodies that target tumor cells which allows other cells like CLTs and macrophages to recognize, attach to and kill tumor cells

Question 8

how cancer cells evade the immune response

Answer 8

◦ Sometimes cancer cells do not express MHC making them less susceptible to T cells. (BUT Lack of MHC also makes them susceptible to NK cells).
◦ Tumor cells may mask the expression of tumor antigens
◦ Tolerance- No immune response if the tumor antigens are a lot like normal cells
◦ Immunosuppression- tumor cells produce anti-inflammatory cytokines e.g. TGF-α