Immunotherapy

By:

Ray & Kelly Lewis

David Duke

Catherine Hanson

Richard Hildreth

What is immunotherapy?

Immunotherapy is a means of fighting disease by altering the body's immune response. Often used in the treatment of allergies, immunotherapy calls for administering increasingly larger doses of offending allergens in order to gradually build up the body's ability to tolerate exposure to the offending substance. Experimentally, immunotherapy is also being used in the treatment of cancer.

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The Immune System

The immune system consists of several different types of white blood cells, located throughout the body, that work together in a highly integrated way.

The immune response begins when a macrophage encounters a foreign body. The macrophage literally eats the substance, digests it and then displays certain pieces of the invader, called antigens, on its surface. These antigenic fragments alert the helper T cell to begin a precisely choreographed attack against the foreign intruder. The helper T cell that is called to action is unique in its ability to respond to the antigen displayed. Then, the human body produces T cells, each programmed to detect a specific antigen.

Immune System … cont’d The helper T cell begins the attack by binding to the macrophage via the T cell's

antigen receptor. This union that makes immune cells cluster, stimulates both the macrophage and the helper T cell to exchange chemical messages between themselves and with other cells of the immune system. The macrophage releases cytokines called interleukin-1 (IL-1) and TNF, or tumor necrosis factor. IL-1 alone enhances the ability of dendritic cells to form immune cell clusters and stimulates the helper T cell to release interleukin-2 (IL-2). IL-2 in turn causes T cells to secrete gamma interferon, which instructs other helper T cells and a different class of T cells, the killer T cells, to multiply.

At this point, the killer T cells begin shooting holes in the infected host cells. Simultaneously, the proliferating helper T cells release substances that signal another type of lymphocyte, the B cell, to begin multiplying and differenting into antibody-producing cells.

The antibodies released by the B cells bind in a lock-and-key fashion to antigens on the surfaces of invaders that have escaped macrophages. This interaction makes it easier for the macrophages and special killer T cells to destroy unwelcome entities.

Retrovirus Vector

Retroviruses are a class of enveloped viruses containing a single-stranded RNA molecule as the genome. Following infection, the viral genome is reverse transcribed into double-stranded DNA which integrates into the host genome and is expressed as proteins.

Herpes Simplex Virus

Immunotherapy & Cancer

Experimental cancer immunotherapy is exploring a variety of approaches. Some of these are:

The enhancement of the co-stimulatory signal required for T-cell activation.

Genetically engineering tumor cells to secrete cytokines that may increase the intensity of the immune response against them.

The therapeutic use of cytokines, and Increasing the activity of antigen-presenting

cells.

Immunology & Cancer

Immunotherapy & Cancer

Cancer Antigen Immunotherapy

Principles of cancer antigen immunotherapy:  

1.Human malignancies are immunogenic: Vaccinating cancer patients with their own cancer cells induces the patient’s immune system to recognize the cancer.

2.Activated effector lymphocytes can be an effective treatment for immunogenic cancers.

3.Susceptibility to cancer antigen immunotherapy is dependent on delivering high numbers of activated effector lymphocytes as early as possible during disease progression.

4.Cancer antigen immunotherapy can be delivered with few negative side effects.