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Cell-Mediated Response

Cell-Mediated Response

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Description:

This lesson will investigate a cell-mediated immune response.

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Tutorial

What's Covered

This lesson will cover cell mediated immunity by taking a look at:

  1. Cell Mediated Response
  2. The Process

1. Cell Mediated Response

Cell mediated immunity is a response taken against a threat that has entered a cell. Remember, antibody mediated immunity is a type of response that takes place before the threat has actually entered the cell and involves antibodies. However, those antibodies are ineffective to pathogens once they've entered the cell. Another way to get rid of those pathogens once they've entered the cell needs to exist, and that's where cell mediated responses come into play.

Term to Know

    • Cell-Mediated Immunity
    • A type of adaptive immunity in which T cells respond to target cells that have invaded body cells.

Cell mediated response involves T-cells and NK-cells. NK stands for Natural Killer cells. T-cells, are a type of lymphocyte, a specific type of white blood cell. There are two different kinds of T-cells:

  • Helper T-cells- have a lot of different roles in the immune system, but one of their main roles is to help activate other cells that play roles in this immune response.
  • Cytotoxic T-cells-their role is to attack abnormal cells in the body that have been compromised.

ExampleA cell that's been infected with a virus or a cancerous cell

Terms to Know

    • Cytotoxic T Cells
    • A type of T cell that works to kill target cells.
    • Helper T Cells
    • A type of T cell that works to boost adaptive immune responses.

2. The Process

Let’s take a look at what is actually happening when a pathogen, such as a virus, has compromised a cell. The first step happens outside of it. Dendritic cells, a type of phagocyte, will engulf foreign objects, such as this virus. The dendritic cell will start to process and digest that virus, and then present that virus on its MHC complex. Presenting it in this manner alerts the immune system to jump into control and to target this virus.

This is when helper T-cells are going to come into play . They are going to come up to this MHC complex and see if it has the receptor that fits. Different helper T-cells have different receptors, and, if it doesn’t fit, another will try. The helper T-cell with the proper receptor will bind to that MHC complex containing that virus particle, and activate the helper T-cell. After this it will then start to make copies of itself. Those copies will start to differentiate or specialize into different types of cells.

They can specialize into something called effector helper T-cell. These release cytokines, which are particles that get released to activate cytotoxic T cells. Cytotoxic T-cells can cause apoptosis of compromised cells which is programmed cell death. Cytotoxic T-cells can differentiate also into either memory cells or effector cells. Memory cells are a type of cell that will protect the body in the future if it is exposed to this pathogen again and will know how to deal with the virus more quickly.

Term to Know

    • Apoptosis
    • Genetically programmed death of a cell which can be caused by chemicals that T cells release.

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Summary

Cell mediated response is the immunity that takes effect when a pathogen has entered a cell. It involves helper T-cell and cytotoxic T-cells. The process involves the dendritic cells engulfing a pathogen like a virus and present it on its MHC complex. From there helper T-cells will try to bind to the virus. Once one attaches, it will activate. From there it will replicate and specialize. Effector cells will release particles that will activate cytotoxic T-cell. These will cause apoptosis of cells compromised by a pathogen. The cytotoxic T-cells can also specialize into more effector cells and memory cells.

Keep up the learning and have a great day!

Source: Source: THIS WORK IS ADAPTED FROM SOPHIA AUTHOR AMANDA SODERLIND

TERMS TO KNOW
  • Cytotoxic T Cells

    A type of T cell that works to kill target cells.

  • Helper T Cells

    A type of T cell that works to boost adaptive immune responses.

  • Cell-Mediated Immunity

    A type of adaptive immunity in which T cells respond to target cells that have invaded body cells.

  • Apoptosis

    Genetically programmed death of a cell which can be caused by chemicals that T cells release.