T-lymphocytes and cell-mediated immunity

Question 1

where are lymphocytes produced?

Answer 1

by stem cells in the bone marrow

Question 2

where do T-lymphocytes mature?

Answer 2

in the thymus gland

Question 3

what do T-lymphocytes respond to and what response is this known as?

Answer 3

only respond to antigens that are presented on a body cell (rather than to antigens within the body fluids)

called cell-mediated immunity or the cellular response

Question 4

what does each T-cell have? what does this do?

Answer 4

a specifically shaped receptor site on the surface of its membrane

an antigen presenting phagocyte binds to the T cell (helper) that has a complementary shaped receptor site

Question 5

once the T-cell (helper) binds to the APC, what happens?

Answer 5

the APC secretes interleukin- 1 which is a type of cytokine

this stimulates the selected T-cell to undergo mitosis and clone

this whole process is called the CLONAL SELECTION THEORY

Question 6

what do cloned T-cells differentiate into?

Answer 6

helper T-cells, cytotoxic (killer) cells and memory T-cells

Question 7

what do cytokines released by the Helper T-cells do for cytotoxic T-cells?

Answer 7

stimulate cytotoxic T-cells to release perforin which puts holes in the cell membrane of cells with a foreign antigen

the holes lead to water entering by osmosis and the cell bursts (cell lysis)

Question 8

what is differentiation? why is this important for lymphocytes?

Answer 8

when cells develop special features and adaptations that enable them to carry out a specific function

Tc cells- develop ability to release perforin, which is important because it allows Tc lymphocytes to specifically target APC’s and therefore destroy infected cells

Th cells- develop ability to release cytokines that:
-stimulate phagocytes to carry out phagocytosis
-stimulate Tc cells to release perforin
-stimulate B lymphocytes to activate and begin humoural response resulting in antibody production and lasting immunity against specific antigen