Cell Mediated Response Flashcards
(10 cards)
What do T cells recognise?
Antigen presenting cells.
Where are T cells made and where do they mature?
They are made in the bone marrow and they mature in the thymus.
What cells does the cell mediated response involve?
T cells and body cells.
Why is the cell mediated response specific?
Because T cells respond to antigens on the surface of cells only.
What is an antigen presenting cell?
Any cell that presents a non-self antigen on their surface.
Give 4 examples of Antigen Presenting Cells.
Infected body cells - will present the viral antigens on their surface.
Cancer cells - will have abnormal shaped self-cell antigens.
Cells of a transplanted organ - will have different shaped antigens on their surface compared to your self cell antigens.
Macrophage - has engulfed and destroyed a pathogen and will present their antigens on their surface.
Why are T cell responses described as cell mediated?
Because T cells only respond to antigens which are presented on cells and not antigens detached from cells and within body fluids such as the blood.
Describe the cell mediated response.
1)Once a pathogen has been engulfed and destroyed by a phagocyte, the antigens are positioned on the cell surface. This is now called an antigen presenting cell.
2)Helper T cells (a type of T lymphocyte) have receptors on their surface which can attach to the antigens on antigen presenting cells.
3)Once attached, this activates the helper T cells to divide by mitosis to replicate and make large numbers of clones.
4)Cloned helper T cells differentiate into different cells.
5)Cytotoxic T cells destroy abnormal or infected cells. They release a protein (perforin) which embeds in the cell surface membrane and makes a pore so that any substance can enter or leave the cell. This causes cell death. This is most common in viral infections because viruses infect body cells.
What can the cloned helper T cells differentiate into?
Some remain as helper T cells and activate B lymphocytes.
Some stimulate macrophages to perform more phagocytosis.
Some become memory cells for that shaped antigen.
Some become cytotoxic T cells.
Why do you get a sore throat when you have a cold?
The cytotoxic T cells are destroying infected body cells in your throat.
