3.2.4.3 - Cell Mediated Immunity Flashcards
Which type of immunity are T-lymphocytes mainly involved in?
Cell Mediated Immunity (they are just used to stimulate B-cells in humoural immunity)
Where can non-self antigens be found that T-lymphocytes may bind to?
- The surface of an antigen presenting cell (phagocyte)
- Body cells invaded by a virus may present viral antigens.
- Transplanted cells from organ donors.
- Cancer cells
- Toxins produced by pathogens.
Can T-lymphocytes bind to non-self antigens floating around freely in the blood?
No - they can only bind to foreign antigens that have been presented on an antigen presenting cell e.g. phagocyte.
How do cytotoxic T lymphocytes (Tc) protect against disease?
They kill cells infected by pathogens or cancerous cells.
They produce a protein called perforin.
Perforin creates holes in target cell membranes, which kills the cell.
Where do T-lymphocytes mature?
In the thymus
Where are all lymphocytes produced?
Bone marrow
Where do B-Lymphocytes mature?
In the bone marrow.
What is meant by cell mediated immunity?
An immune response that does not involve the production of antibodies.
Results in the production of cytotoxic T cells that can protect against pathogens.
Describe the process of cell mediated immunity (immunity that does not result in the production of antibodies).
- Phagocytosis of foreign material by phagocyte.
- Foreign antigens from material are presented on phagocyte.
- Specific T-helper lymphocyte (Th) binds to foreign antigen (clonal selection)
- Attachment causes Th cell to undergo mitosis (clonal expansion).
- Cloned T cells can:
- become memory cells for rapid future response.to same pathogen.
- stimulate phagocytes to engulf via phagocytosis.
- stimulate B cells to divide and release antibodies (humoural response)
- activate cytotoxic T cells (Tc) cells to kill.
What can the cloned T-lymphocytes do after clonal expansion has taken place in the cell mediated response?
- become memory cells for rapid future response.to same pathogen.
- stimulate phagocytes to engulf via phagocytosis.
- stimulate B cells to divide and release antibodies (humoural response)
- activate cytotoxic T cells (Tc) cells to kill.
what is an antigen?
foreign protein that can stimulate an immune response/production of antibodies
what is an antibody?
Protein specific to an antigen
produced by B cells/secreted by plasma cells