The sequence of events taking place in the humoral response are outlined below.

1) Macrophages digest pathogen and present antigen on MHC II markers to specific TH cells.
2) Specific TH cells bind to MHC II complex via specific cell receptors.
3) TH cell is activated by interleukin I released by the macrophage
4) Activated TH cell proliferates and releases interleukin II.

The 4 steps above are also the same for cell mediated response. The video clips below will outline the humoral response further.

5) Specific B cells bind to antigens via receptors (antibodies) on the cell surface.
6) Activated TH cells release interleukin II that activates the specific B cells.
7) Activated B cells proliferate and differentiate into memory and plasma cells. Memory cells persist for a long time ready to respond to a second invasion by the specific antigen. Memory B-cells are long-lived cells that quickly proliferate in response to an antigen that first stimulated their production. These rapidly generate a population of antibody-producing plasma cells during subsequent exposure of the immune system to the antigen that inititiated a primary immune response or to an antigen that is structurally related to this antigen
8) Antibodies attach to free floating antigens and the antigens on the surface of infected cells and pathogens, locking them into a matrix and making it easier for phagocytes to attack.

View the video on the right and answer the questions below.

B lymphocytes are found in the liver lymph node bone marrow .

Billions of B lymphocytes are present in our body. Each B cell is unique and sensitive to one antigen a number of antigens all possible antigens

Hundreds of thousands of receptors are present on a B lymphocyte's membrane. These receptors recognise only one antigen a number of antigens all possible antigens that is why there are so many on the surface of the cell.

Explain the central idea of Burnet's clonal selection theory.

Describe how B lymphocytes respond to infection.

What is the function of antibodies and where are they produced?

A shown in the video, helper-T cells, in the humoral response, cause proliferation of selected B cells which then produce B plasma cells and memory cells. Without helper-T cells, a selected B cell may never proliferate or if it does you will get a reduced number of B plasma cells (thus less antibodies) and no memory cells!
What is the contribution of helper-T cells in long term immunity?

1) What initiates a humoral response? macrophage red blood cells bacteria

2) What is the role of class 2 MHC proteins (MHC II)? To bind to the antigen and destroy its structure. to bind the antigen and transport it to the surface of the macrophage where it is displayed. To bind to the antigen molecule and prevent it from docking onto other receptors within the cell and outside the cell.

3) What is an antigen presenting cell? A macrophage that binds pathogens, such as bacteria or viruses, to its surface. A macrophage that digests an antigen A cell with antigen fragments attached to its surface.

4) An antigen presenting cell can bind with any Helper-T cell. true false

5) When a Helper-T cell and a presenting cell dock interleukin-1 is released by the Helper-T cell true false

6) Interleukin-1 stimulates the Helper-T cell to engulf and digest the pathogen to release interleukin-2 multiply quickly and grow in size

7) Interleukin-2 causes the Helper-T cell to grow in size divide release antibodies

8) Discuss the process by which the right Helper-T cell is selected to multiply

9) Explain how activated Helper-T cells activate B cells to become antibody producing Plasma cells.

10) Cytokines are any of a number of substances that are secreted by specific cells of the immune system and carry signals locally to neighboring cells. They are a category of signaling molecules that are used extensively in cellular communication. The action of cytokines may be autocrine or paracrine, but not endocrine, Why?

Clonal selection forms an important part of the primary immune response. A primary immune response is invoked when a new antigen invades the body. Traveling through the circulatory system, the antigen will inevitably meet up with the lymphocyte that has the correct antibody pattern.

Each lymphocyte has a unique antibody on its surface. Antibodies are proteins that bind with harmful antigens to neutralize them. If the immature cells have antigen receptors that match any of the bodies own tissues, then those particular cells are destroyed. This is the basis of an autoimmune response in diseases such as rheumatoid arthritis.

What is an autoimmune disease?

Candida is a fungal infection. The anitgens on the fungus resemble proteins on the surface of cartilage cells found in joints. Candida fungal infection can lead to rheumatoid arthritis, an autoimmune disease. Explain how.

Using butcher's paper outline the sequence of clonal selection process with diagram and short captions. In your diagram label the following words and offer clear explanations for each.

Macrophage 1 mark
Antigen presenting cell1 mark
Class II MHC protein1 mark
Plasma cell 1 mark
B lymphocyte 1 mark
Helper T cell (show the interaction between this cell and the antigen presenting cell. Indicate in your diagram the specific nature of this interaction ) 2 marks
Interleukin 1 and interleukin 2 (describe the action of each) 2 marks
Cloned Plasma cells (discuss its function) 1 mark
Cloned B memory cells (discuss its function) 1 mark
Antibodies 1 mark

On the right is diagram showing concentration of antibodies in the blood as a response to a primary and subsequent infections of the same antigen.

What can you say about the response time of the second exposure as compared to the first?

What can you say about the level of antibodies produced during the second exposure?

What can you say about the level of antibodies remaining in the blood weeks after the first and subsequent exposure to the antigen?