January 23, 2013

Allergy and Immunity

Allergies are a malfunction of the immune system; therefore, any discussion about allergies has to start here.

Over millions of years our bodies and those of our ancestors have perfected highly-developed defense mechanisms against microbial invasions and noxious chemical substances. It comprises a system of cells and organs known as lymphoid organs. These organs affect the growth, development and release of white blood cells and include the adenoids, appendix, blood vessels, bone marrow, lymph nodes, spleen, thymus and tonsils. The white blood cells fight infections and are important to the immune system. They search the body for infectious organisms.

Under attack by a flu virus or exposure to e coli, the immune system marshals white blood cells and other parts of its security force.These race to the site of the assault frequently propelled by increased body temperature - fever.

Phagocytes often are the first cells on the scene. These large scavenger white blood cells patrol the bloodstream, looking for possible invaders. When they find one, they engulf, digest and destroy it.

Other components of the immune response react when presented with specific antigens. The most important players in this fight are two types of lymphocytes that learn to "recognize" and destroy the foreign invaders.

B cells, the first type, are white blood cells that produce antibodies, which circulate in the blood and lymph streams. The first time B cells encounter a new foreign substance, they make antibodies in response to the intruder's antigens. When the antibodies come across that specific antigen again, they attach themselves to it, marking it (and with it, the entire foreign substance or microorganism) for destruction by other cells. Antibodies also summon phagocytes and body chemicals to the site of an infection and move them into action against the antigens.

T cells, the second type, are specialized white blood cells that monitor and coordinate the entire immune response, which includes recruiting many different cells to take part in that response. Some T cells, the T helper cells, signal the B cells to start making antibodies. Other T cells, the T killer cells, attack and destroy substances that they recognize as foreign. Once the foreign antigens have been defeated, scavenger phagocytes called neutrophils, a type of white blood cell that can surround and destroy invading organisms, and macrophages, another form of engulf-and-destroy cell, arrive to clear up remains of the inflammation.

Symptoms such as sneezing, coughing, vomiting or diarrhea are the by-product of all this activity, expressing the presence of illness as well as providing the means by which to eliminate it. We cough mucus that is dangerous if it accumulates in our body. We eliminate toxic substances from our intestines by vomit or diarrhea.

When a body is sensitive to certain allergens such as seasonal ragweed, cedar, gluten - and these allergens cannot be avoided - the body's immune system is forced to mount a sustained defense against an ongoing assault. Although the initial response is heightened when the allergen is contacted, the population of white blood cells becomes depressed and remains lower for the duration of the exposure. This deficiency compromises our ability to stave off the ill effects of virus, bacteria or toxins to which we are exposed. 

Inflammation becomes chronic and so do its symptoms.

In medical terminology, any word ending in itis denotes inflammation. Dermatitis. Arthritis. Bursitis. Tendonitis. Conjunctivitis. Meningitis. Encephalitis. Bronchitis. Sinusitis. Otitis Media.Pericarditis. Myocarditis. Endocartis. Colitis. Vasculitis. And so on. All are fires that the immune system is too weak to put out. All permit the body to develop more serious expressions of disease and/or death.
 

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