Allergies: The Downfall of the Immune System


A properly functioning immune system is a well-trained and disciplined biological warfare unit for the body. The immune system is quite amazing; it is able to identify and destroy many foreign invaders. The immune system can also identify cells that are infected internally with viruses, as well as many cells that are on their way to becoming tumors. It does all of this work so the body remains healthy.

As amazing as the immune system is, it sometimes makes mistakes; allergies are the result of a hypersensitive immune system. The allergic immune system misidentifies an otherwise innocuous substance as harmful, and then attacks the substance with ferocity far greater than required. The problems this attack can cause range from mildly inconvenient and uncomfortable to the total failure of the organism the immune system is supposed to be protecting.

If you have read about immunity, you should know about lymphocytes, also known as white blood cells. Lymphocytes are a fundamental component of the immune system; when they make a mistake it can create an allergic response.

There are two types of lymphocytes: B‑lymphocytes (B-cells) and T‑lymphocytes (T-cells); both types help guard your body against foreign substances such as invading bacteria, viruses and toxins. They move freely through and among the tissues of the body, travel through the walls of blood vessels, and move between the various lymph nodes and lymph channels; namely, everywhere.

Lymphocytes act like traveling customs agents; everywhere they go, they are busy checking every cell they encounter. Whenever they discover a cell that seems threatening, they immediately begin countermeasures against it. When a lymphocyte encounters a particle or cell with surface marker molecules that identify it as a foreign invader, it performs a microscopic version of taking fingerprints and mug shots of the invader.

As these foreign invaders lead to the production of antibodies, they are called antibody generators, or antigens. After a B-cell identifies an antigen, it will make its way back to a lymph node, change into a plasma cell and produce antibodies specifically engineered to fight that particular threat.

There are five basic types of antibodies, known as Immunoglobulins, or Ig. Each is classified by type with a letter suffix: IgA, IgD, IgE, IgG, and IgM; however, the Ig responsible for allergic reactions is IgE.

In a properly functioning immune system, the genetic code contains enough information to enable the lymphocytes to distinguish between threatening and non-threatening proteins. In an allergic person’s immune system, the lymphocytes cannot tell that the protein ingested as part of a meal containing shellfish is not invading the body.

The B-cells of an allergic person, “misinformed” at the genetic level, lead to the production of large quantities of IgE antibodies that attach themselves to mast cells throughout the body, which is scientifically known under the name of sensitizing exposure.

Although mast cells are found in connective tissue, they have one thing in common to the allergy sufferer. They contain histamine, which is an important weapon in the body’s arsenal for fighting infection. Unfortunately, when released into the body in too high a quantity, histamine is a potentially devastating substance.

It takes between one week and ten days of sensitizing exposure for the mast cells and basophils to become primed with IgE antibodies. Then, if the allergen comes along again, it triggers a destructive domino effect within the system known as the allergic cascade.

When mast cells and basophils are destroyed, their stores of histamine and other allergy mediators are released into the surrounding tissues and blood. This leads to dilation of surface blood vessels and a subsequent drop in blood pressure. The spaces between surrounding cells fill with fluid. Depending on the allergen or the part of the body involved, this brings on the various allergy symptoms, some of the most common are sneezing, wheezing, diarrhea, or vomiting.

There are three techniques commonly offered by doctors to help allergy sufferers: avoidance, medication, and immunotherapy. Many allergens, once identified, can simply be avoided; if you know you are allergic to shellfish, you do not eat it.

Unfortunately, many allergens—like pollen, mold, dust, and preservatives—are very difficult, if not impossible, to avoid. These can often be managed by using medications such as antihistamines, decongestants, cromolyn sodium, corticosteroids, and in the case of anaphylaxis, epinephrine.

Immunotherapy, on the other hand, is expensive, time consuming, and not without risk; but it is often the only hope a person has for leading a normal life. It consists of a series of injections of the offending allergen, beginning with a very weak dilution and gradually building in strength to a maintenance dose that may be continued over time. The injections help the immune system produce fewer IgE antibodies, while also stimulating the production of a blocking antibody called IgG.

It is amazing how our immune system acts as an internal army against any external invasion that threatens our body; however, it seems this army can sometimes be the threat itself. Like anything else around us, our immune system has its downfalls; but this does not, by any means, take from its great role in protecting us.



The article was first published in print in SCIplanet, Spring 2014.

Cover banner: Image by wayhomestudio on Freepik

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