It's called an immune system because it is actually a network of cells, tissues, and organs that all work together in various ways to protect your body against what are perceived as threats to your health.
The main threats that concern the immune system come from germs, also known as bacteria or viruses. But fungi and other parasites can also threaten health.
When any of those "invaders" try to break into your body, the immune system kicks in to either prevent their entry or, failing that, to seek them out and destroy them. Unfortunately, the immune system sometimes misinterprets threats and ends up causing disease, rather than preventing it. This can include asthma, allergies, arthritis, and other disorders.
The Immune Response
The cells of your body carry proteins that communicate the cell's purpose. When these proteins identify a cell as "self," all is good. But when the proteins scream "foreign," the immune system launches an attack, known as the immune response. Cells carrying the "foreign" – or "non-self" – protein that trigger immune system attacks are known as antigens, or in the case of asthma, as allergens.
The system is, under regular circumstances, able to tell the difference between foreign invaders and the body's own cells. This is the mark of a healthy immune system. But, sometimes, the line between "self" and "non-self" cells blurs, and that can lead to an abnormal immune response.
Sometimes, the immune system mistakes self proteins for non-self proteins and begins to attack its own body. This is called an autoimmune disease, and includes certain types of arthritis and diabetes. At other times, the immune system mistakes what should be a harmless substance – such as pollen or dust mites – as a threat, which results in an allergy.
The immune response is both complex and specific. Once an alarm is sounded, it produces different chemicals and cells to combat each different type of threat. The immune system also has a sophisticated communication system.
In fact, like any good general, the system allows its "lieutenants" (the individual cells and tissues) to direct operations locally. In effect, these regional "leaders" run their own show as needed by recruiting other cells to work with them and regulating their own growth and behavior in response to what is going on in their area.
How the Immune System Is Structured
The immune system has "centers" all over your body that help produce immune responses. These centers are called lymphoid organs, and include:
- Lymph nodes
- Bone marrow
- Thymus, a small gland behind your breastbone
- Spleen
- Circulatory system (blood vessels and lymph vessels)
White blood cells called lymphocytes live in the lymphoid organs. They are key players in the immune response, because they travel around the body via blood vessels or specialized circulatory organs called lymphatic vessels. They patrol the body looking for antigens and allergens.
The immune system consists of many different types of immune cells, such as:
- Phagocytes
- Eosinophils
- Basophils
- B cells & C cells
- Mast cells
Some of these immune cells do battle with any and all antigens, while others are more specialized. Likewise, some communicate via direct contact, while others do so through chemical messengers.
Immune cells exist in relatively small numbers when you are healthy. But, when the alarm is sounded, the cells multiply quickly into a full-fledged "army" of protectors.
Antibodies and The Immune System
The ultimate goal of many immune cells is to produce weapons known as antibodies. Each antibody produced is specific for its target. For asthma allergens, the antibody produced is immunoglobulin E, known as IgE for short. IgE's natural role is to protect the body from parasites, but it has proved to be the culprit in allergies and asthma as well.
Immune cells involved in the type of immune response that occurs with allergic asthma include eosinohils, basophils, and mast cells. These types of cells bind to their targets and deliver a lethal burst of deadly chemicals, slaying on contact.
The Immune System and Allergic Asthma
Allergic asthma is associated with a hyperreactive immune system. A number of factors may play a part in making a person sensitive, or allergic. Research is ongoing to gain a better understanding of the underlying mechanisms.
However, we do know that in such people, the immune system overreacts and responds to common environmental substances, such as grass pollen or house dust, as though they were as dangerous as a deadly virus. Antibodies such as IgE are released to attach and neutralize the threat. Each of these antibodies is specific to the particular kind of asthma trigger that you've been exposed to.
When the immune response is triggered, it causes inflammation in your airways. This inflammation results in airways that are narrowed and tightened. The airways' lining also produces excess mucus. Those responses together make it more difficult to breathe and cause the following asthma symptoms:
These symptoms generally persist until enough time has passed for the immune response to subside or until medication is taken that lessens the degree of inflammation.
The newest treatments for asthma center on modifying the immune response, rather than just treating the after effects, or symptoms. The medicines are actually an alternate antibody form called a monoclonal antibody. They block the action of the immune system antibody. Presently, there is only one asthma medication on the market that acts on the immune system. It is called Xolair, and is known as an immunomodulator.
Source:
National Institutes of Health, National Institute of Allergy and Infectious Diseases, National Cancer Institute. United States. NIH. Understanding the Immune System: How It Works.: NIH Publication No. 03-5423 09 2003.
<http://www.niaid.nih.gov/Publications/immune/the_immune_system.pdf
