5.3 t-lymphocytes & cell-mediated immunity Flashcards
what is the definition of an antigen?
any part of an organism/substance recognised as non-self by the immune system & stimulates an immune response
where are antigens commonly on?
cell-surface membranes
where are lymphocytes produced?
stem cells in the bone marrow
where are B lymphocytes matured in?
bone marrow
what does humoral immunity do?
involves antibodies in body fluids
which type of immunity do B lymphocytes trigger?
humoral
where are T lymphocytes matured in?
thymus gland
what does cell-mediated immunity do?
involves body cells
which type of immunity do T lymphocytes trigger?
cell-mediated
what does T lymphocytes only respond to?
a single complementary antigen on antigen-presenting cells
describe the process of cell-mediated immunity. (4)
1- pathogens invade body cells / taken in by phagocytes
2- phagocyte places antigens on its cell-surface membrane
3- receptors of T-helper cells fit exactly onto antigens (complementary)
4- attachment activates the T-cell to divide & clone genetically identical cells (by mitosis)
what are the 4 ways that cloned T-cells could be used?
1- develop into memory cells for rapid response to future infections
2- stimulate phagocytes to engulf pathogens (by phagocytosis)
3- stimulate B-lymphocytes to divide & secrete antibodies
4- activate cytotoxic T cells
what is the role of cytotoxic T cells?
kills abnormal cells & infected body cells
how do cytotoxic T cells kill abnormal cells?
produces protein that makes holes in cell-surface membrane
-> membrane is freely permeable & dies
what is the name of the protein that cytotoxic T cells produce?
perforin
