Their increased activity may lead to an allergic reaction. The immune response is a coordinated effort. All of the immune cells work together, so they need to communicate with each other. They do this by secreting increased levels of a special protein molecule called cytokines that act on other cells. There are many different cytokines. Examples of these are interleukins, interferons, tumor necrosis factors, and colony-stimulating factors.
Some immunotherapy treatment strategies involve giving larger amounts of these proteins by an injection or infusion. This is done in the hope of stimulating the cells of the immune system to act more effectively or to make the tumor cells more recognizable to the immune system.
Caution: There are people who promote unproven therapies as immune system boosters. Be careful when evaluating these claims. The following are types of immunotherapies that are commonly and legitimately used in traditional and scientific medical practice.
If the appropriate part of the offender touches this receptor, a wire is tripped. An alarm system inside the cell sets off the eating process macrophages are known for, which is called phagocytosis. The cell wraps itself around the bacterium and engulfs it, isolating it into a small bubble called a phagosome.
The macrophage now has a live prisoner. Because they lack teeth, macrophages must use chemicals to digest their mouthfuls. These chemicals are contained in compartments called lysosomes, which are filled with the harshest substances found in the body and are strongly acidic.
The signal that compels the macrophage to engulf the bacterium also causes the cell to start concocting a new batch of this digestive brew in order to break down the captured cell. The lysosome fuses with the phagosome and quickly digests the bacterium, breaking it into small pieces of debris. After digestion, the chemicals are then neutralized in order to protect the macrophage from being damaged. Some digested particles are put to good use: They are displayed as trophies on immune molecules studding the outside of the macrophage, which are checked routinely by other white blood cells for evidence of infection.
This hands off the immune response of the generalist macrophage, which will kill anything suspicious, to specialized immune cells that mount targeted attacks against the specific invader. The resulting well-coordinated campaign deals the knockout blow and clears the body of the infection. Without the intelligence provided by the macrophage, these specific-acting cells would be unaware of the infection.
Our little play ended as this story does, with a body cleared of infection and able to continue thriving, thanks to a little help from the macrophages within it. Just like wrestlers come in different age and weight classes to match an opponent, some T-cells are made for certain germs. The special fighter T-cells in your immune system are called killer T-cells.
The helper T-cells can go into the lymph node and find the one killer T-cell matched to the invader and call them into the fight. T-cells to the rescue! The macrophage shows the ID tags antigens from the invader to an inactivated killer T-cell. This cell then activates and makes more and more copies of itself.
This army of killer T-cells will follow the path of cytokines to the injury and begin the full-scale attack against the germs. These activated killer T-cells scan all the skin cells around your paper cut. They try to find the special antigen that marks invader cells. The antigen can even alert them to an invader if its hiding inside of one of your skin cells.
Once that antigen is found, the killer T-cells shoot out cytotoxins that destroy the antigen and any skin cell it has infected. The macrophage then comes and gobbles up the dead, germ-filled skin cells to keep your system clean. The B-cells catch wandering viruses. Finally, depending on the type of germ, the helper T-cell can ask the B-cell to join in the fight. This last defender, the B-cell, is important because it can trap, or mark, the germs that haven't yet infected a cell.
The B-cell shoots out antibodies, which we can think of as nets. Just like the killer T-cell, the B-cell will make more and more copies of itself in your lymph nodes before it heads to the infection. Germs that T- and B-cells have fought off successfully are remembered so they will be easier to fight in the future. When all germs are destroyed, the battle is over. The B- and T-cells go back to your lymph nodes, and the macrophage returns to patrol the skin, looking for new infections.
The B- and T-cells that have fought the infection in your skin now have experience fighting those specific germs so they become memory cells. Memory cells give your body a great advantage if you get infected by the same germs. The memory B- and T-cells get a huge head start and can build their cell armies in half the time during the next germ invasion. For more information on how the immune system battles invaders in the body, visit Viral Attack. About the author: Kimberly Repp is a local government public health epidemiologist in Oregon and a graduate of Arizona State University.
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