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An Inflammatory Response

What happens when you get a SPLINTER????????

Your body’s method of fighting infections is extremely complex. The exact response depends a lot upon the foreign material that is trying to infect you. It also depends upon where the infection takes place. The simulation we will act out admittedly takes the very complex immune system and simplifies it a lot, but it’s a good “first look”. We can learn a lot about the basics of the immune system if we act out what happens when you get...a splinter!!!!

Here are the steps that take place when you get a splinter:

When the splinter punctures the skin...

  1. Bacteria will enter the skin.
  2. Platelets unleash a series of chemical reactions which forms a clot.
  3. Mast cells, a special type of stationary white blood cell, release a chemical called histamine.
  4. Histamine increases blood flow to the area.
  5. Histamine also allows capillary walls to widen and open up to release macrophages, another type of white blood cell.
  6. Macrophages, a type of white blood cell, engulf some of the bacteria and destroy them. (Similar large cells you may hear about are neutrophils and dendritic cells.)
  7. Used macrophages and destroyed bacteria are sent into drainage channels called lymph vessels. Lymph vessels ultimately drain into the vena cava.
  8. If all the bacteria are destroyed by this process, great!!!In fact, many simple inflammation responses end here. But let’s go further…
  9. If some bacteria still remain, macrophages will travel along lymph vessels to lymph nodes (or to the spleen). They will display markers from the bacteria to white blood cells in the lymph nodes (or spleen) called T cells.
  10. There are several types of T cells:
  11. Helper T cells will signalKiller T cellsto destroy infected cells, thus also killing the invading microbes in those cells.
  12. Helper T cells will also signal another type of cell, the B cell, to divide and produce antibodies. The antibodies will disable the remaining bacteria.
  13. Regulatory T cells serve to end the immune response so that it does not become excessive and T cells do not end up destroying the body’s own tissues.
  14. Fresh macrophages gobble up the disabled bacteria and destroy them.
  15. Some T and B cells become “memory cells” for later encounters with the same invader.

You will get to play a part in the drama called “The Splinter”.

You will be either...

  • A bacterium – a harsh invader!
  • A platelet – dedicated to forming a clot to stop loss of red blood cells.
  • A mast cell– secreting chemicals to start the battle.
  • A macrophage – a bacteria eater!
  • A Helper T cell - a messenger with information about the invasion.
  • A Killer T cell - another line of defense against the bacteria.
  • A Regulatory T cell – keeping other lymphocytes from getting out of control
  • A B cell - a producer of antibodies, the last line of defense against the bacteria

Bacteria –

Your job is to invade the skin! You will try to reproduce before the body’s defense chemicals destroy you! You hang out at the place where you invaded the body. You have some unique characteristics which identify you. These characteristics are your “markers”.

Platelets –

You are a type of blood cell. Your job is to initiate a series of chemical reactions that will cause a clot to form to prevent blood from leaking out of the body. In this situation, your “clot” is formed when you weave your tape strips across the hole created by the splinter. This prevents blood from leaking out of the hole. You don’t fight the bacteria, however.

Mast cells –

You are a special type of white blood cell living near the skin. Your job is to release the chemical histamine from your spray bottle. Histamine increases blood flow to the area. This means more white blood cells will come to the area to fight the invading bacteria. Histamine also allows the walls of the capillary to open up enough to let the macrophages through so they can attack the bacteria. Therefore, when you spray your histamine you can open up the capillary walls to allow the macrophages to get to the bacteria.

Macrophages –

You are a type of white blood cell. Your job is to destroy the bacteria. You can not do this until the capillaries open up enough to let you out to attack the bacteria. In this simulation, one macrophage can destroy only one of the bacteria. When you kill one of the bacteria, you go into the drainage ditch called the lymph vessel. You go to the lymph node. You take the bacteria’s markers and show them to the Helper T cell. You will also later eat bacteria that have been disabled by antibodies.

T cells –

You are a type of white blood cell called a lymphocyte. You live in the lymph nodes of the body. You don’t do anything until the macrophages come along and show you markers from the bacteria that are invading.

  • If you are a Helper T Cell, you stimulate the Killer T cells, the B cells and fresh macrophages.
  • If you are a Killer T Cell, you destroy infected cellsonce you receive a signal from a Helper T Cell. (This is hard to simulate, so you’ll be “destroying” bacteria.)
  • If you are a Regulatory T Cell (sometimes called Suppressor T cell), you stop the B cells and other T cells once the crisis is over.

B cells –

You are a type of white blood cell called a lymphocyte. You spend time in the bloodstream “on patrol” and you also circulate throughout the lymph vessels and lymph nodes. When a Helper T Cell alerts you, you make antibodies that will destroy the bacteria. When told, throw your antibodies at the remaining bacteria and disable them!

Questions following the Splinter Drama –

The Human Immunodeficiency Virus operates by infecting certain white blood cells, namely Helper T cells andmacrophages. So why do people who contract HIV develop Acquired Immune Deficiency Syndrome (AIDS) when the virus is left untreated? What does Acquired Immune Deficiency Syndrome really mean?

Based on what you know now, what is happening inside your body when you receive a DPT vaccine? DPT vaccines are used to prevent diphtheria, pertussis (whooping cough) andtetanus, which are all bacterial infections. Use specific vocabulary words you learned from this activity.

Why do you think you may need to get a “booster shot” or receive vaccinations in several small doses?

Based on what you know so far about how the immune system works, why do you think it’s difficult to create vaccines for Influenza and adenovirus (the common cold virus)? Use specific vocabulary words you learned from this activity.