Cell recognition and the immune system

Question 1

What are the specific and non-specific responses of white blood cells and what does it mean?

Answer 1

Phagocytes - non-specific - any non-self cell will be detected and destroyed, it is not specific to a cell.
Lymphocytes - specific

Question 2

What is a phagocyte?

Answer 2

macrophage (type of white blood cell) that caries out phagocytosis.

Question 3

Where are phagocytes found?

Answer 3

In the blood and tissue

Question 4

Describe the process of phagocytosis.

Answer 4

1. Phagocytes in the blood and tissue will be attracted to any chemical debris released by pathogens and move towards them
2. The receptor binding points on the phagocytes will attach to the antigens on the pathogen via these receptors.
3. The phagocyte changes shape to engulf the pathogen
4. Once engulfed, the pathogen is contained within a phagosome vesicle.
5. A lysosome within the phagocyte will fuse with the phagosome and release its contents
6. The lysozyme enzyme is released into the phagosome which hydrolyses the pathogen. This destroys the pathogen
7. The soluble products are absorbed and used by the phagocyte. The antigen is placed on the cell surface membrane so the phagocyte becomes an antigen presenting cell.

Question 5

What are T lymphocytes (T-Cells)?

Answer 5

White blood cells involved in the specific immune system

Question 6

Where are T lymphocytes made?

Answer 6

They are made in the bone marrow but mature in the thymus.

Question 7

What are antigen presenting cells?

Answer 7

Any cell that presents a non-self antigen on its surface.

Question 8

Why is the process called cell-mediated

Answer 8

because the t-cells only respond to antigen presenting cells.

Question 9

What is the process of the cell mediated response?

Answer 9

1. Once a pathogen has been engulfed by a phagocyte, the antigen is placed on the cell surface and an antigen presenting cell is formed
2. Helper T-cells have receptors on their surface which can attach to the antigens on the APC
3. Once attached, it activates the helper t cells to divide by mitosis in order to replicate and make clones
4. The cloned t helper cells differentiate into different cells.
   - Some of them will remain as t helper cell and activate b lymphocytes
   - Some stimulate macrophages to perform more phagocytosis
   - Some become memory cells for the particular shaped antigen
   - Some become cytotoxic T cells (killer t-cells)

Question 10

What do t killer cells do?

Answer 10

Destroy abnormal or infected cells. They release a protein called perforin which embeds inside the cell surface membrane and makes a pore allowing any substance to enter or leave. This causes cell death.

Question 11

What is a monoclonal antibody?

Answer 11

An antibody produced from identical B cells

Question 12

What is one example for using monoclonal antibodies in medical treatment?

Answer 12

It binds to specific antigens